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eli5: What is multimodal distribution? With examples, please :) | Consider height. Adult women are about five inches shorter than adult men. If you look at just the distribution of women's height, it's a normal distribution - many clustered around the mean, few at the extremes. Likewise, if you look at just the distribution of men's height, it's a normal distribution.
But if you look at the distribution of all human height, you end up with a bimodal distribution. The mode (most common value) of female height is about five inches less than the mode of male height while the variance is roughly the same. Adding them together preserves these two modes, thus 'bimodal' or 'multimodal'.
In general, when you see multimodal distributions in real world data, it implies that you're combining two or more distributions that have different characteristics. | 59 | 20 |
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ELI5: Why have so many people gotten cancer from dust/chemicals inhaled or absorbed due to the 911 attacks? | I hadn’t really thought about it before but I realized I never actually understood why this happens. How does exposure to certain carcinogenic substances for a few hours manifest itself into cancer years or even decades down the road? I understand how living next to chemical plant or smoking cigarettes can cause cancer from long term exposure but I don’t really get how it can happen so quickly. I was also curious as to if they have a rough idea of what the carcinogens were coming from (I.e burning paint, plastics, etc.). | Whenever you do cell damage, cells repair and grow. And every time that happens, there is a chance of cancer mutations. These people breathed in lots of microscopic glass and asbestos that continually causes damage that results in repair and mutation. On top of that, some of the nasty things breathed in were also chemical carcinogens that cause cancer. | 39 | 25 |
[Harry Potter]Dementors make humans experience extreme depression, that being the case how do they keep people in Azkaban from just lying down until they die of hunger/thirst? | The effect of a Dementor probably isn't on/off so much as an intensifying area of effect enhanced if the Dementor is focusing on you... If you're further away and there's only 1, and it's not actively draining you it'll take longer to set in and probably won't be as profound.
There's a passing comment by Fudge, when he's explaining the Black situation to Madam Rosmerta in "The Prisoner of Azkaban", and he says Black was given maximum security, with Dementors outside day and night.
Extrapolating from that statement, there are patrols of Dementors throughout the place, with at least standard and high-security, maybe other denominations. The Dementors may not necessarily enjoy feeding on someone 24/7 as much as letting them recover somewhat before bringing another crashing wave of cold, despair, misery and eventually apathy on them. So, some of the prisoners may be largely left alone and only experience a partial or cyclical effect. It'd probable still be pretty horrific, even if it's not as intense as having the Dementors there all the time.
And Black did mention that within a few hours people went from defiant, to miserable to screaming for someone to help them. Eventually even the strong-willed ones succumbed to apathy and stopped screaming. Some of them stopped eating. He also said the Dementors could sense when death was approaching, and behind excited, gravitating towards the person they'd managed to tip over the edge. | 20 | 15 |
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Best practices to avoiding impropriety? | As a woman in science, especially in the current #metoo era, I've always been acutely aware of men being sexually inappropriate with me (which has happened many times, both inside and outside professional settings). However, as my career has advanced and I've gained more power, I realize that now I'm in a very different position, one where I could conceivably be the person in power if a sexually inappropriate thing happened. It feels weird.
I work in a large, friendly, sometimes raucous research group; I have young men and women mentees who I directly supervise. Our group generally gets together socially once a week or so, often with alcohol and other disinhibitors involved.
I'm wondering, what is my, and any other mentor's, obligation in such a situation? Should we recuse ourselves from socializing with mentees (eg no PI/postdoc, or postdoc/grad student, or grad student/undergrad socializing)? Am I overthinking all of this and as long as no one goes home with anyone it's all gravy? If a mentee makes a flirty statement, is it enough to roll your eyes and change the subject, or as the person in a position of power, do we (I) have an obligation to say, "hey man, let's keep it all above board"?
Other thoughts on the topic - how do we keep a cordial, collegial environment without crossing any lines? | I think you can model collegial socialization by drinking moderately and behaving well.
It would be a kindness to shut down impropriety. Let mentees know that it's not only unwanted, but unprofessional. | 66 | 56 |
ELI5: Why is soaking a wound in warm salt water or swishing salt water around in your mouth good for combating infection? | Soaking a wound in salt water can kill bacteria because it essentially draws the water out of the bacterial cells. However it's important to note that for wound care soaking in salt water is generally not recommended. This is because while salt kills bacteria it also kills healthy cells that are necessary for wound healing.
When you get a cut the best thing to do is irrigate it with normal saline (which can be bought at any drug store) or regular tap water. This is just to get whatever immediate dead skin, dirt, bacteria are there out. The next step is to cover the wound.
Another false remedy is hydrogen peroxide. Although it kills bacteria through a different mechanism then salt it is not recommended for wound care because it can prolong wound healing. Hydrogen peroxide kills bacteria but also kills good skin cells | 171 | 281 |
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ELI5: Why does my head produce a seemingly infinite amount of mucous when im sick? | When we get sick from an infection, the body produces an inflammatory response to protect us from the bacteria or virus. As part of this response, signalling substances are produced and released by the mucous-producing cells lining our nose. More blood flows to the area and body water leaks out between the cells of the membranes in an attempt to wash away the dead tissue, white blood cells, and bacteria/virus (hence the yucky yellow/green colour) leading to a runny nose. Unfortunately, swelling of tissues is also part of the inflammatory process, and that is why we get congested sometimes as well. | 108 | 304 |
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ELI5 - how does the body decompose in a casket? | How does the body decompose in the casket? Does it eventually just become goop? Do the bacteria within multiply and eat you up? | Yes, the microbes on and in your body multiply and digest all the flesh, organs, etc. The ossified parts of bone will stick around for a good long while, but given enough time, those will be broken down and digested too. | 22 | 36 |
Why is Lead a good radioactive shield? | Lead (and other dense metals like cadmium) are good at shielding gamma radiation because they are dense. High atomic number and relatively short bond length means there are a lot of electrons for incoming photons to interact with. When the photons that make up the gamma radiation interact with the electrons and transfer energy to them. The same will happen with any material with electrons, but dense metal has more electrons, so better attenuation.
Lead is not so good for other types of radiation. Alphas are massive and have high charge so are stopped by almost anything, including lead, but also paper and several centimeters of air. Betas will be stopped by lead but produce x-rays in the process (Bremsstrahlung radiation) so they are better shield by a lighter material like tin or plastic.
Neutrons are a different story. They are uncharged and don't interact with electrons. To shield neutrons you must get them to collide with a nucleus and transfer energy to it, slowing the neutron down. The energy transfer happens best when the nucleus is of similar mass to the neutron (ie, a H nucleus). For this reason, materials with lots of hydrogen are best for neutron shielding. Paraffin wax is often used. | 91 | 180 |
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ELI5: What is “international law” and who enforced it? | "International law" is the set of treaties, compacts, and conventions to which various nations have all agreed. It is enforced through lawsuits and through international regulatory agencies, such as the World Trade Commission, the International Criminal Court, or the like. Sometimes, the suits can be filed in a country's domestic courts, as well as the courts of the other nation, as well. | 30 | 46 |
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[Mass Effect] How do you picture the role of humans in galactic politics changing after the events of ME3? | Humans played a major role in uniting the galaxy to victory, so that could put them in high regard among the other species. That and now the Citadel is in orbit above the Earth could mean it becomes a new hub for galactic politics. | 11 | 16 |
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ELI5: Why does macaroni and cheese lose so much flavor when refrigerated then reheated? | When you re-heat things in a microwave, water molecules are what absorb the microwaves and receive the energy. With things like cheese, that makes the water kind of separate out and makes the cheese more 'soggy and stringy' instead of 'foamy'. Texture changes taste.
If you re-heat your Mac and cheese in an oven instead of a microwave, it will be much better. | 6,469 | 10,775 |
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To what degree should casual readers of philosophy care about authorial intent? | This question opens onto a massive field (philology, hermeneutics etc.), but it can be interesting to juxtapose what authors intend to mean and what they do mean, what they intend to do, and what they do. Intention in philosophy can, and has, been quite broadly construed - attaining truth, providing laws that govern experience, comprehending Being - and since philosophers as philosophers can *share* intentions their exploits can be contrasted with each other. This procedure is not external to philosophy, all philosophy has used previous philosophies, if not as material, as its stage.
But insofar as intention objectifies itself (minimally in language, sound etc.), it is beyond the controlling scope of the individual's interiority. Yet even there the subject is not in full possession of their intentions anymore than anyone can be wholly present to themselves. The primacy of the author has long since past for most. Those still holding to intention as the source of meaning are confronted with the problem that the meaning of any intention must itself be understood and so cannot be a ground, must be relative. (i.e. is hard to understand what Kant intends without a minimal understanding of the history of philosophy, enlightenment etc.) | 13 | 24 |
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ELI5: Why do cars use a visual measurement for the engine's temperature rather than degrees? | This is a classic example of good instrumentation design. Must people don't know what a "good" temperature is, so showing the actual number requires them to learn and think more. A gauge that reflects meaningful analysis like cold, normal, hot, and "too hot" is actually more useful to most operators. | 52 | 15 |
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ELI5: Why is 1 hand more dominant than other? Why can't we use both hands equally? | A number of studies on task laterality have suggested both hands are dominant, but for different purposes.
Your dominant hand is active-dominant and used for production (i.e. twisting open jars, writing, throwing things, etc.), whereas your non-dominant hand is passive-dominant and used for stabilization (i.e. holding the jars still, holding the paper, providing balance, etc.).
Edit: grammar | 38 | 43 |
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My professor wants to use one of my assignments in his next textbook | My econ professor from last year emailed me today asking if he could use one of the assignments I turned in for his class as a way to open his new Econ textbook (MBA)
I'm not opposed to this, curious if there's any sort of compensation/credit/something else that would be reasonable for me to ask for in return? What is standard for this sort of thing? | I would expect your prof would identify you by name and give credit, but there’s zero chance you’re getting authorship on the book or the chapter. I’d also be very surprised if you got any money. Your prof should write you a terrific letter of recommendation if that is helpful. | 401 | 210 |
CMV: I think student should be able to test out of almost every class. | I think students should be able to test out of any class, at the very least, any of those at the high school level or higher. I don't think it makes any sense to have a student sit through a class to learn things that he can already prove he knows.
Basically, I just want reasons why sitting through a class that a student already understands makes sense.
**Some obvious arguments and their counters**
> Tests might not grasp everything taught in the class, allowing the student to miss possibly important information.
I'm assuming these class tests would cover everything covered in the course, or at least be designed to determine the student's knowledge well enough.
> There are other things that take place in the course that develop the students skills, not just teach knowledge.
I'm also assuming these tests would make sure that the student has a mastery of the subjects rather than a simple acquaintance.
> What about classes like literature, and the like? Classes where students learn things that are bigger than other classes (Dead Poets Society plug).
This is why I specified "*almost* every class." Obviously there are some classes that teach things that can't really be tested, and of course the student would still have to take those classes, or we might just remove them from the education system altogether.
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edit: I apologize, but I must be done for the night. I will reply to any additional arguments tomorrow and will still award a delta to anyone who 'Cs my V.' | Part of getting the credit for a degree or diploma is putting in the effort over time to get something done. Mastery of the knowledge is an important part of the process, but displaying that you can actually do the coursework is another.
If i'm an employer I'd rather hire the employee who graduated with a B average but can put in a solid 40 hour week of effort over the genius with perfect recall and a very lazy work ethic. | 55 | 200 |
ELI5: How do non optical finger print biometrics such as on the Galaxy S7 differ from optical based ones? | Yes I've searched and seen the post about smart phone fingerprints being "faster" than traditional, but how is it actually imaging the print? | Optical scanners work by taking a picture of your finger then processing that image for things like edge detection. This takes time but the hardware is relatively cheap.
The capacitive scanners some devices use is essentially a row of tiny touch screens. They can detect the raised ridges on your skin by touch. This data can be processed in many different ways but for the most part it's simpler - the ridges on your finger are either touching or not touching a part of the sensor. It's sort of like a black and white image - no color data, and the edges are far easier to detect. This has the potential to be faster but the hardware is more expensive. | 15 | 75 |
How far under the ocean does the water extend? Or better yet, how far under the ocean before the ground is dry again? | I know under ground there are water tables, is it the same under the ocean? do they extend deep? how far down under say the pacific ocean floor would you have to go before you were at dryness again? | The oceanic lithosphere (crust and part of the upper mantle) has a layered structure that comprises of various igneous rock which are crystalline and impermeable in varying structures (massive peridotites, dolomitic dykes, pillow basalts etc). On top of these there is a layer of sediment that varies in thickness depending on the age of the crust, which is in turn reliant on the type of ocean. (for example the pacific is a closing ocean and features far older crust than the atlantic which is currently opening. So near or at a spreading centre the thickness of sediment will be extremely small or non-existent leading to the impermeable basalt being on the ocean floor and as a result for it to become "dry" again merely venturing below the ocean floor would be required.
However further away from spreading centres thicker and varying sediment makes the question more complicated. This is because the water would penetrate the sediment to a certain extent, but how much would depend on a number of factors foremost of which being the type of sediment. The limiting factor on the penetration would be when the dewatering effect would take place, this is when the pressure would result in water being "squeezed" out of the sediment, and as a result it would be dry again. | 33 | 184 |
[Indiana Jones] Is every world religion "true" in the Indiana Jones Universe (including books if anyone's read them)? | No, it is not that every religion is "true" but rather there is some underlying truth upon which some religions have been extrapolated from.
So there is an Ark of the Covenant, a Holy Grail, and weird glowy potato rocks; and Judaism, Christianity, and Hinduism have incorporated the existence of these things into their own beliefs. That no more makes those religions "true" than "Hot Shots! Part Deux" is "true" for referencing real-life individual Saddam Hussein. | 268 | 255 |
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ELI5: How signals, be they cell phone signals or data through internet lines, are transmitted along their medium without becoming overwritten or scrambled by other signals also travel through the same medium. | If data is transmitted through pulses that designate 1's and 0's, how do you get multiple signals going through undersea cables or whatever without totally scrambling the data?
I feel like I'm completely misunderstanding how data transfer works.
EDIT: Thanks for the responses. lex418787 in particular. I think I understand cell towers now, but can anyone explain the internet's system to me? I can see that different frequencies make sense for the cell's radio waves, but does the same apply to electricity? | There are two main ways.
One is called TDMA (Time-division multiple access). In this scenario, everyone that's on a particular cell-tower takes turns transmitting data. You might get 1-2ms, and then the next guy gets 1-2ms, and so on in a big circle. The turns happen so frequently that you don't notice it happening. Naturally, if you have too many people then the circle gets too big and people start to notice the degradation of quality. So what really happens is the cell tower doesn't let too many people join the circle, the newcomers just get "Service Busy" or "Service Denied" on their phones. GSM phones use TDMA (AT&T, T-mobile, etc.)
The other is called CDMA (Code-division multiple access). In this scenario, each user gets an orthogonal code to use. Think about an xy-graph. You can move a dot in the X-direction (left & right) without affecting the Y-direction (up & down). So, you could have 2 users, one person moves in the X-direction, and another moves in the Y-direction (kind of like the knobs on an etch-a-sketch). Both people can send data at the same time without affecting each other. In the real world, there are many many different codes, and the cell tower can differentiate between all of them. Phones detect which codes are not in use, and when you make a call your phone uses an unused code. However, there are still more phones than codes, so if too many people try to talk then they'll get the "Service Busy" message. CDMA phones work on Verizon, Sprint, etc. | 12 | 23 |
What is the maximum theoretical efficiency of an air turbine and how close can we get to it with current technology? | The maximum theoretical efficiency of an open air wind turbine is defined by Betz's law to be 59.3%. But if instead the turbine was inside a circular tube of constant diameter, and had a pressure drop of so many pascals across it, how would an ideal turbine behave? As in what would the air flow rate through it be, and how much energy would it extract from this flow? (Given a certian air density) How close can current technology get to that figure?
edit:
This is in the context of a solar updraught tower. There is negative pressure at the bottom of the tower due to the buoyancy of hot air in the tower (stack effect) compared to outside. If there were a turbine in the tower, how much energy could it generate?
My situation is as follows: the tower is 20m diamater. The negative pressure generated by the stack effect is 630Pa. If there were no obstructions in the tower, roughly 7500 cubic metres of air per second will flow up the tower. Since the air density is 0.938 kg/m3 and the air is rising at 24 ms^-1 , one cubic metre of air will have the kinetic energy of 270J. There are 7500 of these per second, so the total kinetic power is about 2*10^6 watts.
That is for an open tube with no restrictions. A turbine will act as a restriction for the air (like a resistor in an electrical circuit), so the flow rate will be lower. I was just wondering if there was a rule-of-thumb equation or number concerning the flow rate through an ideal turbine given a pressure difference (or how much it will impede the air flow stated above), and how much energy will be captured by it.
By "efficiency" I mean the proportion of the kinetic energy in the rising air captured by the turbine.
| Modern multiple stage bladed turbines typically reach 60–70% efficiency, while large steam turbines often show turbine efficiency of over 90% in practice. Volute rotor matched Tesla-type machines of reasonable size with common fluids (steam, gas, and water) would also be expected to show efficiencies in the vicinity of 60–70% and possibly higher. | 17 | 103 |
Eli5: What is an api and why is it useful? | From what I understand, it is a package of software that another company creates, so that a startup can use it and doesn’t have to code as much backend?? I’m only partially understanding this...
edit: thanks everyone, this conversation has helped me understand the nuance | ELI5 Answer: Think of an API like the controls to a car. You've got a gas pedal to go forward, a brake pedal to stop, a steering wheel to turn, etc. You've also got information about the car - how fast it's going (speedometer), how fast the engine is turning (tachometer), how much gas is in the tank, etc.
You don't need to know *how* the gas pedal makes the car go forward or the details of how the fuel tank reads its level. In fact, the 'under the hood' operation varies wildly from car to car, but since the car's interface is (roughly) the same, you can get in just about any car and drive it.
The set of controls and information is like the car's API. "Turn this wheel to make the car go to the right. Look here to see how fast you're going." is like a website's API saying, "Give me a string of text and the ID of a parent comment, and I'll post a reply to that comment". | 11,556 | 8,693 |
Eli5 Imagine how much money and resource is spend shipping water around the world just part of everyday products. Why can we buy products then add the water at home? | Many things containing water cannot be isolated from the water and have their desired properties simply by reconstitution. These could be complex solutions involving chemicals "dissolved" in oil plus chemicals "dissolved" in alcohol and the parts dissolved in water. Food products, for example, are a complex mixture of the above.
Another method would be concentration and dilution. But this is also very problematic because many things are simply too dangerous when concentrated. A dilute acid cleaning product cannot simply be concentrated and sold, for example. Highly concentrated acid is too dangerous to handle.
In general, technology and businesses are not silly. They recognize the issues involved and would definitely want to save costs. Examples are that most sodas are bottled locally - the local manufacturers buy a syrup, dilute and pack it locally to reduce costs.
If you want to know more, you have to be more specific. What particular "water" products are you thinking of? | 29 | 17 |
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CMV. Some lives are worth more than others. | Truth be told, I don't necessarily believe this myself, but it's hard to make what I would consider to be a compelling argument against this.
The only halfway decent argument is that life in general are an unknown quantity; you never know what someone is going to be in the future. Still, this argument fails in that it inherently recognizes that the concept of a life's worth exists, and that there exists such a thing as a highly valued life and a lowly valued one.
I suppose another argument against this is the idea that worth is a highly subjective concept; still, that's more a philosophical argument than anything.
The concept that all lives are equal in worth is a pleasant one, but in reality, it doesn't hold up. | By what objective measure can you make this statement? What is it about Life A that makes it worth more than Life B?
We have trouble evaluating worth when we can put something like money next to it (like is a blanket made from your dead grandmother worth more than a blanket that cost $100?). i kind of question your ability to evaluate lives without some kind of measurement. | 11 | 30 |
ELI5: How is it possible that there are "unsolvable" mathematic equations? | My general understanding is that math tends to make a lot of sense. Obviously this is very simple but 2+2 obviously equals 4. 3y=6, y obviously equals 2. How complex does math actually get that there are equations that aren't solvable (so far) and what are they? What parts aren't solvable? What is it that we don't know that we need to know before we can solve them?
Edit: For clarification, I'm talking about major mathematical problems that no one's found a solution to, not equations that have answer that make no logical sense. | Something to understand is that mathematics is essentially philosophy. It's a discipline about logic, not numbers. Most people have the misconceived notion that math is about numbers. It's not, numbers is just a tool used in a lot of math problems. A lot of math problems boil down to having a set of information, and a conclusion, no numbers may be involved. Prove that there is a relationship.
The unsolvable problems right now are essentially relationships that we've observed but we cannot prove through logic as of yet. No one has been able to perform the mental gymnastics to solidify the relationship. | 338 | 453 |
ELI5: What are Parole Board Members suppose to be looking when assessing whether an inmate should be Paroled or not? | In light of the OJ Simpson Parole hearing today.
EDIT: dammit I forgot a "for" | There are 8 criminogenic risk factors that can be used to predict the likelyhood someone will recidivate. Of those factors, 5 are directly linked to criminal behavior and 3 are supporting, but not directly linked. Factors include criminal history, education/employment, financial situation, housing, family/marital situation, drug/alcohol use, companions, and leisure time. | 14 | 15 |
ELI5:How did ancient Romans do complicated math using Roman numerals? | The normal method of calculation in ancient Rome, as in Greece, was by moving counters on a smooth table. Originally pebbles (calculi) were used. Marked lines indicated units, fives, tens etc. as in the Roman numeral system. This system of 'counter casting' continued into the late Roman empire and in medieval Europe, and persisted in limited use into the nineteenth century. | 21 | 31 |
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Foucault, 'the death of man'. | In the order of things, at the end of chapter 9, Foucault talks about man's disappearance. What exactly does he mean by this? | The idea of the 'the human' or 'Man' was, for Foucault, an invention of the enlightenment and modernity more broadly. The notion that man was an object or category that could be studied as a thing in itself. Foucault suggests that this is just a symptom of modernity and eventually wed get passed it and realize that it doesn't quite make sense to study Man because it isn't actually true that such a universal sort of category exists. He's sort of predicting the post-human turn in philosophy and social theory and popular culture as well, hence the figure of the cyborg as an example. | 16 | 36 |
ELI5: What is P value and why is 0.05 so important? | When doing studies that have some probability factor involved in it (say randomly sampling people), there is a chance that you may conclude a fact about something simply because of random chance in your study. Say for example it can happen that you flip a coin 4 times and every time it lands on heads. And then you conclude that all coin flips must land on heads as a result of that, which is wrong. This happened because of purely random chance.
A p value denotes the probability of your experiment happening the way it did the way it did. A p value of 0.05 means there is a 5% chance that the results you got support your conclusion not because there is a bias for some reason towards such results (say a coin is heaver on one side than another) but because of just dumb luck.
0.05 is just known as the gold standard for concluding that something is "statistically significant," that is probably didn't happen because of dumb luck. But smaller p values are better, and should be possible to reach if there is a true correlation although this generally means doing a more expensive study. | 1,710 | 1,502 |
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Why do brambles have thorns AND delicious fruit? Surely the fruit is there so animals will eat it and spread the seeds, so why guard it and discourage them from eating the fruit with sharp thorns? | Most plants with fruit are adapted to have a particular kind of animal eat it, not just any animal. Blackberries are adapted to be eaten by birds, IIRC. Birds carry the seed a long distance and shit it out somewhere new. Small animals aren't as bothered by the thorns as we are.
Without the thorns, it's more likely that some large herbivore would come along and eat the whole plant, or if it just ate the berries it'd probably eat them all at once and deposit them in one place. It's also possible that the seeds can pass unharmed through a bird's short digestive tract but would be killed by a ruminant's much more thorough digestion. | 36 | 17 |
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[Futurama] How does the government work? Where does The Central Bureaucracy fit in with DOOP and the government of earth? | Bureaucrats are unelected officials selected for their knowledge of bureaucracy and adherence to rules. They do the work of seeing the rules are followed.
The elected government *makes* the rules. Mostly this is Nixon's head pretending to head a democracy by holding rigged elections. Most of the actual laws were already made centuries ago, so he reviews the ones which might need to change, and adjusts them in his own best interest.
Earth has successfully conquered all other easier-to-conquer planets in order to form DOOP, which is also only nominally a democracy headed by earth.
This is why Earth is known as the easiest planet to conquer, all the other easier planets are already conquered, so it gets that title by default. Most other planets can't be arsed to actually conquer Earth, because then they'd have to put up with earthlings. | 44 | 48 |
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Why does the IMF continue to force countries to enact austerity policies despite blatantly admitting themselves that they're bad? | unless you think austerity policies are actually good (please explain). | Context matters. Austerity in a recession in an otherwise "economically healthy" country is bad. In a country that's out of control going into debt and about to default or experience accelerating inflation, "austerity" measures may be needed. | 22 | 15 |
Why should we not be allowed to walk around naked? | This is a question that had intrigued me recently. I understand that clothes protect us from the elements and that perhaps over time this has propagated a view of indecency (alongside other things), but I am really interested as to why any of you might think it wrong to go out into public naked. The only two reasons that I can think of are (1) that it exposes children to things they should not see of (2) that is potentially decreases the amount of victims of sexual assault ( I am Islamic and this is most certainly a very large reason as to why women must cover themselves). But I am interested, what do you guys think is the reason we all wear clothes? I am just curiously looking for answers and this is just a random thought which struck me. Do you see it as immoral? Or perhaps just a construct which we abide to -- in which case, why abide to it?? What is the deeper meaning behind clothing??
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Edit: In response to (1) I honestly feel like children will be privy to this stuff so it doesn't matter (I hold the same view in respect to swear words, I don't really care if my child swears. And (2), is this not just a men's issue? I think women should be able to walk around naked -- If a man rapes her, that is his fault. A woman should be able to dress naked. | Stephane Duschenes, owner of Bare Oaks Family Naturist Park in Canada has some great sources and discussions regarding this topic. There’s also evidence contrary to your points 1 and 2. Nonsexual nudity is not harmful, and there isn’t a link between what someone is wearing and sexual assault.
Resources can be found by looking up Bare Oaks or The Naturist Living show. | 61 | 92 |
[Star Wars] If Luke's identity was to be protected from Vader, why did he retain his Skywalker surname? | Two main reasons:
1. Everyone was told that Padme died and her child died with her. Thus Vader and the Emperor *weren't even looking* for Luke and Leia.
2. Obi-Wan took him back to Tatooine - not only is this planet outside of the Empire's jurisdiction, it's a reminder of *Anakin Skywalker*'s past - a past that Vader does his best to avoid. | 50 | 22 |
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Is there a country that is currently decreasing in population due to an aging population? | I'm aware of many countries like Japan that have an aging population due to low birth rates, but I would like to know if any countries are in the midst of a high death rate that might affect the economy and housing market. What type of policies are implemented to support the economy? Would there be incentives to get new families in apartments and housing? | Most of the post industrial west, Russia, Japan.
What you're touching on is known as the demographic transition and it goes like this:
Phase 1: Pre-industrial; high birth rates but also high death rates and thus a reasonably stable population
Phase 2: We get sanitation, vaccines, antibiotics... death rates plummet but people still have a shit load of kids. Populations increase rapidly. This describe most of the industrialized world for the first half the 20th century.
Phase 3: People start to realize that that all their kids can be expected to live into adulthood, a goodly percentage of population is no longer engaged in agriculture (so no need for big families), birth control becomes a thing - Population growth begins to stabilize. So most of the industrial world in the second half the 20th
Phase 4: Material wealth begins to play a role. People make the choice to trade off having more children for security and/or just more shit like houses, vacations, educations, ect... Fertility rates decline below replacement
Phase 5: <- what your asking about now. The more aged populations that result from phase 4 reach a sufficiently old age that high death rates return and the population declines farther. This is a new addition and should be temporary until the cohorts born during phases 3 & 4 end their life course.
For more information see the work of Notestein and also Laundry (1934). | 42 | 78 |
Why do some jobs pay more than others? | Maybe this is a bit of a beginner question. But why do some jobs pay a lot more than others.
Since just about everyone wants to be paid more money, why don’t they move to a higher paying profession?
Besides barrier to entry (cost of education, or difficulty obtaining the degree) I can’t really think of a reason why an equilibrium of salaries doesn’t exist | The BASIC answer to your question is that salary for workers works similarly to price of goods. Supply and demand. As supply goes up, prices go down, as demand goes up, prices go up.
So if you look at the job of cashier for example… there's a much larger pool of people who are capable of being a cashier. Things are changing a bit right now but generally speaking, in the past if a business needed to hire a cashier, the position was not hard to fill. Basically any person in the world could learn to do it.
However if you want someone to be a heart surgeon, you can't just pull anyone off the street to do it. It requires specialized skills and training and therefore the pool of people for that job is much lower. Therefore, it will cost more to hire one. | 43 | 31 |
ELI5: Why do store bought tortillas keep A LOT longer at room temperature than store bought sliced bread? | When it comes to taste, texture, and mold, tortillas last a whole lot longer than your standard sliced bread. I have noticed that this is true for both corn or flour tortillas. Why is that? | Water content and surface. Tortillas are very dry and flat, so there's no water and very little space to grow for mould. Sliced bread has more water and because of all the yeast air bubbles and being sliced has a lot of surface for the mould to latch onto. | 74 | 157 |
ELI5:How can a small amount of medicine (like a pill) affect my whole body? | It's not unreasonable that small amounts of things can have a dramatic effect on the body. A tiny thorn only effects a very small number of nerves (compared to your entire body) which sends a small number of signals to your brain. Yet it can overwhelm your senses. A small amount of poison from a sting can effect your body. Also consider that your body produces minute amounts of hormones to control your body functions.
This is the only way that your body can function. It has to be designed so that small amounts of substances can produce large changes. This is true for any effective system. A large company is controlled by a few people at the top. An airport is controlled by a few people in a tower. An army is controlled by a few generals.
Similarly, your body is controlled by *signals* in the form of chemicals. That's what many medications are. They are signals. Those chemical signals end up creating various larger changes in the body.
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ELI5: why don’t you hear about the history of Africa before colonialism? | Why don’t we learn about Africa’s history before slavery? Was it not documented enough or is it just another systematic racism? | Egypt is one of the oldest civilizations on the planet and we hear a lot about them and their history prior to European colonial era. We also hear a lot about the Caliphate eras of the middle ages and dark ages which controlled much of North and Central Africa, and of Carthage that was in North Africa during the Roman era.
But you are correct that there is not a lot on Central and Southern Africa. That would be because most of those tribal groups did not have written language so we do not have records of their history outside of oral traditions of the groups, or records of them made by other groups.
Also you talk as though slavery was something unique to Imperial Europe and the Americas. It was not. Slavery has existed as long as civilization has existed and virtually every ethnic group on the planet has owned slaves and been slaves at some point in their history. | 2,797 | 1,647 |
ELI5: If diamonds have such a low resell value, why don't 2nd hand diamonds massively undercut the price of new diamonds? And in turn driven up the price of second hand diamond or destroyed the price of diamonds? | I just watched this collage humour video: http://youtu.be/N5kWu1ifBGU and its left me thinking, why hasn't capitalism sorted itself out? Surely the market must be full of cheaper, second hand diamonds, that are identical in quality to those dug out the ground. | I have a friend that's a diamond wholesaler. He buys diamonds in bulk from different places and resells them either alone or placed in a setting. Usually at prices 1/3 - 1/2 of retail. One thing he said to me that always stuck is "there is no such thing as a used diamond". Diamonds don't have mileage or age issues.
The market is definitely full of cheaper diamonds, that are identical to retail store ones, you just have to know where to look. Resell value is only low in comparison to retail value. Diamonds are a luxury item and people pay for what they perceive items are worth. That perceived worth is controlled by corporations and marketing. You can blame the 1948 DeBeers campaign of "A diamond is forever" for that. | 115 | 297 |
ELI5: How does epigenetics work? How much can
your actions change the genes you pass on, and in
what way? | What's it all about? How much can your actions change the genes you pass on, and in what way? Can I use this to influence physical and/or mental capability of my offspring?
EDIT. For clarity. | Your genes are made of DNA. We think of DNA as a pretty static molecule, that never changes or varies once we've inherited it. As it would turn out, there are lots of chemical processes that can happen to the DNA (such as chemicals sticking to it and whatnot). These can happen at any moment in our lives and might have to do with our lifestyle. For example, having a high blood-sugar all your life might sway theses "DNA tweaks" a certain way. These changes are different for each cell, and can also happen in the copies of DNA that get passed on as we're discovering that it seems that sometimes these "DNA tweaks" can get passed on too! This means that we might be passing on effects of a certain lifestyle genetically to our kids. With their DNA pre-tweaked a certain way. It's hard to know how big the effect will be and in what way because we're still trying to understand the exact nature of these tweaks and there's also the nature vs nurture debate where we wonder if they'll have that much of an effect anyways. | 16 | 51 |
Why do a lot of philosophers dislike Continental Philosophy? | It seems to me that quite a lot of philosophy students dislike Continental Philosophy, or more importantly dislike those who like Continental Philosophy. Is this because there is a type of arrogance that commonly comes with Continental Philosophy? Do those who study C.P. have a sort of elitism towards C.P. compared to other types of Philosophy? | Michael Friedman, a philosopher of science at Stanford, has an interesting interpretation, from "A Parting of the Ways" (2000): Analytic philosophy, "in the eyes of many, appears to withdraw from the large spiritual problems that are the concern of every thinking person – the meaning of life, the nature of humanity, the character of a good society – in favor of an obsession with specific technical problems in the logical or linguistic analysis of language. Here philosophy has taken on the trappings of a scientific discipline, characterized by clarity of method and cooperative cumulative progress in the formulation and assimilation of ‘results,’ but at the expense of all contact with the central philosophical problems that are of truly general concern beyond a small circle of narrow specialists. An engagement with the traditionally central problems of philosophy has thus been left to the continental thinkers, but the works of these thinkers, in the eyes of the more analytically inclined, appear to throw off all concern with clarity of method and cooperative cumulative progress in favor of a deliberate and almost willful obscurity more characteristic of a poetic use of language than of ostensibly logical argumentative discourse. The divergence between the analytic and the continental traditions has therefore been an expression within the world of professional philosophy of the much more general split C.P. Snow famously identified between his opposing (and mutually uncomprehending) ‘two cultures’ – that of the scientifically minded and that of the ‘literary intellectuals.’”
edit *Michael Friedman, not Martin | 37 | 38 |
Why do we measure decay in half-lives rather than just lives? | To explain in simpler terms. I've run into a misconception occasionally that OP might be falling prey to. If a certain material has a half life of 100 years that doesn't mean it'll be fully decayed in 200 years, it means about half will decay in 100 years, then half of that half in another 100, then half of that half in another 100, etc. | 5,181 | 3,312 |
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Which topics are trending in contemporary political theory/philosophy? | I'm particularly interesting in *novel* issues which are being debated *now*, rather than merely during the last decade or so. | Some new and interesting work is being done on the moral limits of markets. For instance, even if certain transactions are entirely voluntary, some philosophers hold that there are certain moral limits on what can be bought and sold.
Debra Satz from Stanford has a book called *Why Some Things Should Not be for Sale* (2010). Sandel has *What Money Can't Buy: The Moral Limits of Markets* (2012). Brennan and Jaworski have a defense of markets in *Markets without Limits* (2015). | 12 | 25 |
ELI5: Why is it better to brush your teeth before breakfast rather than after? And why do we need to brush our teeth in the morning if we brushed them at night and didn’t eat anything in between? | It's actually debatable about when is best to brush your teeth throughout the day, but twice a day is considered ideal.
If you choose to brush your teeth after a meal, you should wait at least 30 minutes, to give your mouth time to naturally clean your teeth off.
Why?
Because, all foods have sugar, some are acidic, some foods are harder and rough, and all that brushing right after a meal is doing is taking all of that stuff that can scratch and damage your teeth, and spreading it around. Lets take sugar. It's a sharp crystal that can damage teeth. Imagine that it's sand and your teeth are glass. If you rub that sand around the glass, it will scratch it. Teeth can repair this damage over time, but those scratches can lead to all sorts of things getting stuck in. Acids can also make the teeth softer, which means that if you're brushing softer teeth, you're doing some damage.
On the other side, some dentists believe that brushing before you eat is better. But here's two catches. One: You can not eat anything for at least 30 minutes after brushing. and Two: You should not be rinsing your mouth out, just spit out the paste and swallow whatever is left.
Why?
Because the fluoride in toothpaste takes time to bind to teeth. If you just rinse your mouth out, it washes away the fluoride without giving it time to bind. The fluoride in the toothpaste creates a protective barrier over and around your teeth, preventing damage from sugars, acids, and other things.
So why brush if you don't eat anything?
Have you ever experienced morning breath? This occurs because when you are sleeping, plaque-causing bacteria in your mouth multiply and leave an unpleasant taste and odor for you to encounter when you wake up. Brushing your teeth right away when you wake up helps to rid your teeth of this harmful plaque and bacteria.
Now there are some dentists that say it's best to chew gum before flossing and brushing your teeth. The gum does two things: it activates your salivary glands, cleaning off your teeth naturally, and it can pick out particles that might damage teeth.
If you want the cleanest teeth, do not rinse your mouth out after brushing (it actually specifies on almost all toothpaste labels that only children 2-6 should rinse). Spit out the excess and the amount of fluoride you swallow after is harmless and it will keep your teeth healthier for longer than if you rinse after. | 486 | 365 |
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Why do Microwave ovens set to low cycle high/off in intervals instead of steadily using lower constant power? | I have always wondered when microwaving foods why operating at 50% power for example the food is cooked at 100% power for 50% of the time instead of 50% power 100% of the time.
Is it a functional effectiveness? cost saving?
Why not supply 500w instead of 1000w? | Microwave ovens utilize a device called a cavity magnetron to produce the electromagnetic radiation used to cook your food. The basic gist of how this device works is similar to how blowing air past the top of a bottle creates sound, only with electrons instead of air. If the voltage isn't high enough, then the resonance required for it to operate doesn't occur. Cutting the voltage in half will result in a device that just produces a little heat, and no radiation. Cutting the operating cycle in half produces the desired effect.
Pulsed operation is very common in electronics as a means to produce varied output, as it's generally easier to control. However, there are always side-effects of doing this, like noise from the pulsing itself. Your food doesn't care about this noise, so it's considered acceptable. | 20 | 26 |
ELI5: why do plants get root rot from overwatering, yet you put cuttings in just water to grow new roots? And also just like what’s the difference between that and hydroponic gardening in general? | So, plants grown in hydroponic systems can still get root rot— however... Properly installed hydroponic systems should contain air pumps that help to supply O2 to the plant, as well as a drainage system (ebb & flow system). Root rot occurs in waterlogged soil where O2 is mostly inaccessible.
It might be more helpful to view root rot as the plant's problem. It's not that there's anything wrong necessarily with being in water; it's that the plant is diseased. | 221 | 679 |
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CMV: Natural death (aging) is good for society. | This is almost a direct reply to [CGP Grey's latest video "Why die?"](https://youtu.be/C25qzDhGLx8) and all other arguments in favour of immortality.
Basically, death is the reason we exist as a species, and we still depend heavily on it. Death is a mechanism for evolution, you might think given enough time we would evolve to be immortal, but that's completely wrong. Evolution depends on death, it's why death exists in the first place. If a species doesn't die, they never improve their traits, there is no reason for newer generations, so no evolution. It's the continuous creation of new generations that are just the tiniest bit better what drives evolution, so by definition, you need a natural terminator on the older generations, which is what we call aging.
You might think that since we don't rely on biological evolution in our modern era we don't need death. But it's not just biological evolution what I'm talking about, it's every kind of evolution. It's the evolution of ideas, of concepts, of paradigms and dogmas, and it applies scaringly similarly.
Think about last century, and all of the discrimination and the progress made on racial issues. Who is more likely to support the Civil Acts Act? The 40 something white person that grew up in an all-white house where African-Americans were only unquestionable servants throughout their entire lives, or the kid who was born into a world where for the first time African-American people were able to speak up and be heard, and ask in a meaningful manner for freedom? It was the young people, new to the world and with a fresh mindset, who led the Civil Rights movement. Their perception wasn't clouded by countless memories of blatant, yet accepted discrimination, but was fresh, fully unbiased, and with no stakes in the game.
I'm not saying that all old people are unable to accept change, I'm saying it's way easier to develop blind spots in your perception when you think you know all the tricks in the book, when you think you've seen everything and that things work in some specific way. When you have seen a clock work over decades without ever failing you'll swear on your life that nothing is broken with it until someone new comes along and points out the cracks in the glass, the molding on the numbers. If you grow with it, it blends into the environment. How much stuff is in your surroundings right now that you've just stopped noticing but would remove if you look for it?
We all know resistance to change is a thing, and it's more predominant in fully developed adults. There is no lack of [studies](http://www.gjournals.org/GJMBS/PDF/2013/December/081613784%20Chari%20et%20al.pdf) and [articles](https://www.scientificamerican.com/article/set-in-our-ways/) that showcase this in clear and complete ways (seriously, google "Aging and change").
Imagine if we still had all baby boomers running the country, how easily are you going to change those people's perspectives? There's a reason why companies will always try to hire young people for jobs that involve any kind of innovation, they are the only ones that are coming with a new point of view and who aren't blind to the flaws in the system. A fresh perspective is always valuable, and it's often best to stand aside and let others give it a go.
Our world is famed with stories of reluctant and stubborn older populations holding back the younger ones, and we want to add to that a perpetual exponential increase to them? We're nowhere close to being able to completely redefine the way the vast majority of the world thinks and unleashing wide-spread immortality on these "set in our ways" thinking people would most likely cause more harm than good.
We should value the fact that there's a natural mechanism for washing out the sedimented old minds, even though it means our eventual demise. Its natural occurrence means we don't have to come up with one ourselves, which might just be what we'd end up doing when we notice immortality isn't working. You need to clear away the old to make room for the new. That's why we ended up with a way to achieve this naturally, death and finality are fundamental to change.
| But what are we evolving towards?
The science seems to indicate that we are evolving towards living long lives and increasing our means of reproduction, with reproduction to produce children simply as a means of carrying on our genes.
If we don't need to carry on our genes because we are immortal, then why do we need to evolve?
We can continue to adapt, but we no longer need to evolve.
Your argument seems the same as Cracked's "Why immortality sucks". A similar argument they made is whether or not Thomas Jefferson would help the British in First World War.
But this is largely irrelevant, because with the removal of aging and death we remove many of the barriers which reinforce discrimination and biases.
If we need not fear death but merely discomfort, then the penalties enforced on people for not agreeing with those in power carry less weight.
You can protest without fear because the worst they can do is lock you up for a few years out of your eternity of existence. | 11 | 18 |
ELI5: How are Wall Street analysts able to predict a company's earnings so accurately prior to the company's actual earnings report? | Publicly traded companies are open about their financials. If you look at many of these companies, they give public "guidance" to investor groups and analysts that cover or follow the company. SEC rules require this information to be public. You can find these on many company websites under "investor presentation". Also, much of the analysis is built upon predictable patterns, public info, and building off of last quarter's results.
So TLDR- lots of info is put out there that people who follow these companies read and analyze. The bigger and more traded the company is, the more there is, so it's not really outsiders having clairvoyant knowledge. | 58 | 165 |
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How did complex systems like our circulation system evolve? | I have a scientific background mainly in math and computer science and some parts of evolution make sense to me like birds evolving better suited beaks or viruses evolving to spread faster. These things evolve in small changes each of which has a benefit.
But a circulation system needs a number of different parts to work, you need a heart at least 1 lung, blood vessels and blood to carry the oxygen around. Each of these very complex and has multicellular structure (except blood).
I see how having a circulation system gives an organism an advantage but not how we got here.
The only explanation I have found on the Internet is that we can see genetic similarities between us and organisms without a circulation system but that feels very weak evidence.
To my computer science brain evolution feels like making a series of small tweaks to a computer program, changing a variable or adding a line of code. Adding a circulation system feels a lot more than a tweak and would be the equivalent of adding a new features that required multiple changes across many files and probably the introduction whole new components and those changes need to be done to work together to achieve the overall goal.
Many thx
EDIT Thanks for all the responses so far, I have only had time to skim through them so far. In particular thanks to those that have given possible evolutionary paths to evolve form a simple organism to a human with a complex circulation system. | Here's an intuitive description of one candidate pathway:
(1) Some very simple sea creatures started eating bacteria that floated into them.
(2) Some creatures (like sponges) evolved pores to filter more food from the water. This made them more effective at gathering food.
(3) These pores evolved into long digestive (somewhat vein-like) channels for the water to pass through. This gave them more area to use to digest the food.
(4) Some creatures began wiggling to pump more water through their digestive channels. This gave them the evolutionary advantage of getting more food.
(5) As digestion evolved, some of these digestive channels became internally separate. (So food first passed through the main digestive channel, then was further circulated in secondary channels.)
(6) Some of these secondary digestive channels started evolving "special" water to help transport the food. (This was the precursor to blood.)
(7) Eventually, the circulatory system began to be quite different and separate from the digestive system, although they were both still just a series of tubes.
(8) Instead of pumping the blood by wiggling, some creatures could save energy by just flexing the muscles immediately around their veins.
(9) Gradually, this evolved in to a heart. | 1,649 | 2,651 |
ELI5 Do we all taste the same things? | Do we all taste the same tastes and just do not like particular tastes? Or do we taste everything differently and thus do not like the same tastes? | This is called qualia. It's about subjective experiences. It is completely unanswerable. There is no way to know how another being experiences reality. We can't go inside someone's consciousness to see. | 55 | 24 |
Can we treat identity in the late stage capitalism, as a commodity? | It seems that the identities a person acquires in life share the same mechanisms of market commodities, and that commodities and brands are becoming part of our identity. Can we treat identity in the late stage capitalism, as a commodity by itself? | Class is a form of identity that is not (necessarily) tied to wealth but grants social opportunity and a level of status within a society that be viewed as a non-fungible commodity (a useful and/or valuable thing). Class can and does supervene on other aspects of identity such as religion, race/ethnicity, nationality, sexual orientation, and gender identification.
The British-Ghanaian philosopher and law professor Kwame Anthony Appiah explores this in some of his works. *See* “The Lies That Bind Us.” | 38 | 121 |
A woman with a long history with major chemical corporations told me yesterday that CO2, Diamonds and Pencil Lead were Organic, is she right? | Now to Clarify I work with this woman, L (chemist with history at major chemical producers)
I'm in the IT Department, we had dinner last night with another colleague (PhD environmental biology). Now during the meal they were chatting chemistry and L's work history and such, I wasn't paying full attention because I don't know anything about chemistry.
But basically it came up that anything that contains Carbon is organic. So, being curious I asked L if a diamond would be organic. She says yes, anything that contains carbon is organic. I ask if there's a difference between the term "organic" to a chemist as opposed to a biologist, she replies that "organic is just a Marketing term" but doesn't really answer my question and just acted a bit condescending about the fact that I don't have a chemistry background.
I asked a friend of mine who took high school chemistry and he said he'd never heard of it and that I should ask her if CO^2 is organic, she says it is...
So my question, because she was rude and I wasn't interested in asking again, is
> Is the term Organic meaning anything with carbon in it a term only used as such in chemistry?
I had learned that organic meant that it was an organism, that it had lived at some point or another.
**TL;DR: My coworker told me that any carbon containing compound is organic, but I always learned that organic meant that it was once living.** | The term "organic", in chemistry, is defined somewhat arbitrarily. Some define it as compounds that were at some point part of a living organism. A more common definition is a compound with a carbon in it, but excluding a few groups of compounds such as carbonates, carbides and simple carbon-oxides (such as CO2). Almost all organic compounds contain carbon-hydrogen bonds (C-H).
You'll note the repeated use of the term 'compound'. The definition of a compound is a molecule consisting of atoms of at least 2 different types. By definition, this means that diamond is not an organic compound.
Ultimately, this question is not so much a matter of absolute truth or falsehood, but rather of what the definition of the term "organic" is that one works with. There is no unifying property that separates organics from inorganics that everyone agrees on.
However, the most commonly used definitions consider things like diamond and carbondioxide to be inorganic.
Note that the chemistry notion of organic is unrelated to the agricultural/biological notion. In agriculture, an organicly grown crop is one that has not been treated with artificial products. Again, you can quibble over the exact details (and people often do). | 162 | 140 |
ELI5: Why is processed food "bad" for you? | Sometimes there aren't many other options for a large section of the population, whether due to affordability or other reasons.
Additionally, how can we make healthier processed food choices? | When food is "processed" it generally means that it is altered in someway in between its source and when you consume it. Many foods we eat today are "processed".
Juice is processed by taking fruits and removing the fiber (solid bits). The fiber in fruit is like a natural constraint. eg. it would be tough to eat 10 apples, but easy to drink 10 apples worth of juice. The juice is calorie dense compared to the fruit making it easy to over consume and gain weight. Milk and juices are often pasteurized, pasteurization, the heating of liquids to kill bacteria, being the process they were subjected to. So its tough to generalize and say all processed food its bad for you. It really depends on the process its self.
High fructose corn syrup is the result of processed corn products (glucose) that result in the sweet maple like syrup that they put in everything (fructose). Corn syrup isn't necessarily bad for you in small quantities, but it is very calorie dense. So eating large quantities will result in weight gain.
White bread is also a processed food. They process the wheat by removing the tough outer shell of the wheat where all the nutrients and fiber are found. You end up getting all the calories from carbohydrates without any of the fiber or nutrients, and often people refer to this as "empty calories".
TL;DR all processed foods aren't necessarily bad for you and it depends on the process and your diet as a whole.
Edit: Clarified a few things. | 103 | 141 |
[Raimi Spider-Man] How does organic web-shooters Peter make some of his webs sticky and others not? He catches bad guys in big sticky spiderwebs, but he and MJ relax on a big web and it's not sticky at all. | Spiders have different types of silk, with different properties. Some are sticky and some are not, some are elastic and some are not, etc. They're produced by different glands inside the spider, and they each serve different purposes. For example, a spider's web has "spokes" made of non-sticky silk, while the lines within the spokes are sticky.
Similarly, we've seen Spider-Man produce different types of webbing from his wrists, including variations of sticky and non-sticky, as well as firing the webbing in small compact balls. So it would appear Spidey also has some degree of control over what type of web he wants to secrete from his organic web shooters. | 54 | 24 |
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ELI5: How come online banking transactions still follow bankers hours if it's all computerized? | How come I can't pay a credit card bill that's due on a Saturday, on a Saturday? How come it still takes 2-3 days to electronically pay bills online when I can download pretty much anything from anywhere in the world instantly? | #1
Many systems that process banking transactions use Mainframes which process transactions in batches and more recently in Real-Time using CICS. Most banks uses software that processes banking transaction that were designed back in the late 70s-80s and still work great today. For instance, cashing checks, although there might be an online system that displays the transaction in Real-Time, ultimately it needs to be processed and balanced in a mainframe batch by each bank at the end of their day. So, the Federal Reserve bank or ACH (Automated Clearing House) sends transactions to banks every 4 hours and then there is a delta or EOD file sent at the end of the day, say 6 PM, for banks to process all their transaction in batches; normally mainframe batches run between non-operating that start around 8PM-7AM. This is why SWIFT (same day) money transfers are expensive, they don't use the ACH system rather they use a Real-Time messaging network run by the SWIFT Organization.
#2
Technology was designed a long time ago and modeled around how the human transaction worked and limitation around hardware. With the advent of microcomputers (your PC) and the internet, people expect transactions to happen instantaneously which requires a major overhaul of the software banks use today. That means it costs banks a lot cash in order to redesign the systems and a lot of risk given the systems work well today. For a bank it's not worth the expense and risk to make these transaction live.
#3
By banks keeping the system rigid they can more easily garner fees from its customers as Net Interest Income drops because of the low interest rate environment and losses to other fees based on regulations on capping overdraft fees and late payments. So, a bank could lose millions by allowing its customers to pay, say a credit card bill past 5 PM the same day or allowing the cash to show up in one's account the same day rather than the next. By removing the 5pm rule, they would lose out on all the fees they charge customers that do this. The bastards.
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ELI5: Why can a fetus grow a hand with finger nails but if you cut your finger off it won’t grow a new one? | The presence (and lack) of specific hormones determine what parts of a cell's DNA strand activate (or remain dormant). This basically determines how a cell is going to behave: in how it multiplies and divides, what kind of cell it becomes, etc.
However, once it goes through this process and becomes a specialized cell, it loses the ability to become another kind of cell. It has become specialized and fix. So when you lose a body part, you no longer have cells in that part of the body that have the capability to become the cells you lost. | 16 | 22 |
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ELI5: Why do download speeds start slow and reach full speed later on instead of your full download speed right away? | The internet protocols, particularly the transmissions control protocol, AKA TCP, are designed to probe and understand the link as they go.
So it starts by sending one packet, and if that package gets through it sends two, and if those packets gets through it sends three, this is called the window size. It's the amount of data that's allowed to be in flight but not yet verified.
If it sent it as fast as it could all at once, but it turned out the link could not handle that speed, it would have to send it again, and again.
And to allow for momentary outages if something doesn't arrive as expected, the width falls back in half.
So if your in-flight window is eight packets wide, and one of them doesn't get through, the link will fall back to four packets. And if the four packets get through then it'll increase to five, then six and so on. If it falls back to four and the one of those four doesn't get through it will fall back to two.
The entire purpose of this is to allow the internet to continue to function somewhat fairly as it encounters damage and other problems.
So just like an accelerating car, the protocols are designed to accelerate the flow to get as close to optimally full pipelines as possible without actually causing turbulent failures due to over stressing the various links.
Basically as the stream proves itself the stream utilization increases. If the stream fails it fails quickly.
If it sent all the data all at once at full speed, and the first packet failed then you would have to send all the data you'd sent again, and that would cut your bandwidth in half effectively.
So it's better to sensitively find the boundaries of available flow rather than just keeping on trying to drive a Mack truck through a bicycle lane. | 116 | 58 |
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Could you theoretically "push" a singularity? | Would it be possible to exact a force on a black hole to move it in another direction? Or is the gravity too strong | Two masses will feel each other's gravitational field and respond to them regardless if they are singularities or not. A black hole singularity will still feel other objects' gravitational fields and orbit them like any other celestial bodies. | 24 | 43 |
CMV: One should not bring a kid into this world unless they can afford to pay their college tuition. | Specifically talking about the United States.
College tuition, as in, 18 years from now.
I know this excludes about 95% of the population, and I know everyone wants to make copies of themselves, but it seems very irresponsible.
The two trends are that seem to be increasing relentlously are college tuition costs and percentage of people attending college, I blame the system for this, not the individuals, as the U.S. moves further away from manufacturing, the need for college educating people in our work force increases, there are less and less jobs available that *don't* require college.
It seems downright irresponsible to bring someone into a world that expects them to go to college and be $500,000 (or whatever it will be in 18 years) in debt.
Would like to hear all of your thoughts on the matter.
> *Hello, users of CMV! This is a footnote from your moderators. We'd just like to remind you of a couple of things. Firstly, please remember to* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | There are a huge range of jobs in this country (the US specifically), and relatively few of them require a college education. If the population, over the next few generations, dropped by 95% (your numbers) and all of the working population was college educated, it would utterly destroy the economy. We go from having unemployment to businesses closing left and right because there aren't enough people to work at them. You can't just change birth rates that drastically (nowhere even remotely close to that drastically) and not expect a massive, catastrophic meltdown in society. | 28 | 25 |
How exactly does Laser and doppler cooling work? | I was looking into quantum and atomic clocks and seen laser cooling, as far as I'm aware Lasers work by emitting stimulated radiation so I can see how they could heat things up, can't quite wrap my head around how they would cool though?
Cheers :)
**EDIT** Thanks everyone for your input, it really helped to clear things up! | Electrons absorb photons and reemit them at specific frequencies. Doppler cooling works applying a laser field to what you want to cool at a slightly lower frequency that it can absorb it. Since the atoms are moving, some will move towards the laser and some away from it. The atoms moving away see the laser redshifted, and therefore of even a lower frequency, and ignore it. The atoms moving towards the laser see it blueshifted, enough so as to be of the right frequency to be absorbed and reemited. This process robs the atom of some of it's kinetic energy, since it has to "bounce" the photon away, and so it cools down. Do it for long enough and you get all your atoms at near-zero kelvin. | 29 | 70 |
Famous Philosophers/Philosophical works that deal with Competition? | Nietzsche wrote a lot about what could be considered competition to some extent. A lot of his morality/ontology (not sure which you’d consider it tbh) is based around the concept that life is will, specifically the Will the Power. This means very roughly that the driving force in life is to maximize its potential as much as possible. Since different wills conflict, there is “competition” in nearly everything (including the human psyche).
For example, in section 14 of the Gay Science he writes “Our pleasure in ourselves tries to maintain itself by again and again changing something new into ourselves; that is what possession means. To become tired of some possession means tiring of ourselves. When we see somebody suffer, we like to exploit this opportunity to take possession of him; those who become his benefactors and pity him, for example, do this and call the lust for a new position that he awakens in them “love”; and the pleasure they feel is comparable to that aroused by the prospect of a new conquest.” So for Nietzsche, even love is a conquest, which of course requires at least a bit of competition.
Point being, if you’re looking for a philosopher who’s really into competition, conquest, domination and the like, Nietzsche’s probably your best bet. | 13 | 23 |
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ELI5: Why Doesn't Germany simply withdraw from the EU? | Germany is often seen as the potential savior of the EU right now, with bailouts flying about and member countries sinking deeper and deeper into debt. Germany has been holding strong, has a strong economy, and is oft described as the backbone of the common currency system. So why isn't it in their best interest to revert to their own currency and write the Euro off as a failed experiment? Please note I'm American, and economics isn't my strong suit so be gentle lol. | Germany has a vested interest in keeping the European economy alive and relatively strong. If German left the EU and the entire European economy took a dive, that would come back to bite Germany in the ass in the form of reduced trade and probably "migrant" workers (people who live in other EU countries who go to Germany to try to get jobs). This would end up damaging Germany's economy as well, so the end result would be everyone in a depression/recession. It's in Germany's best interests to keep its trading partners and geographical neighbors economically strong as a means of protecting its own economy from a possible downturn. | 54 | 45 |
[Star Wars] Why did the Republic use Jedi as its generals? | In a universe of trillions, the Republic seemed to select its generals almost entirely from the relatively-small Jedi population. Why? Did the Jedi receive uniquely superb tactics training at the academy? Does the Force make them superior leaders by that large a margin? | - Highly disciplined, not swayed by emotion
- Heightened senses through the Force allow indications of actions before otherwise detectable
- Highly respected leaders readily available to fill a previously non-existent command structure | 79 | 46 |
ELI5: What does it mean to play "Devils Advocate"? | When the Catholic church makes certain important decisions, like making someone a saint or appointing a cardinal, they elect someone to represent the interests of the Devil, as a sort of "let's make sure that we have covered all bases" move. This is to make sure that they are making a good, well-thought decision. The word for "lawyer" in many languages is "advocate", so essentially someone is acting as the Devil's lawyer.
&#x200B;
The term has moved into common English (and probably lots of other languages) to mean the person who brings up a point that people do not necessarily agree with, but should be considered. | 73 | 38 |
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ELI5: What is "lattice based asymmetric cryptography"? | Asymmetric cryptography is a kind of encryption where there are two keys, a public key and a private key. Generally, you keep the private key secret and publish the public key for anyone to see. A message encrypted using one key is decrypted using the other. Anyone can send you a secret message by encrypting it with your public key, so that only you can decrypt it using your private key. In addition, you can “sign” a message by encrypting it with your private key; then, anyone can decrypt it using your public key, and they can be sure that you wrote the message.
Asymmetric cryptography is very important to modern commerce. Secure websites (which these days are most commercial websites) use asymmetric cryptography to ensure that no one can impersonate them; that is, when you're talking to your bank, you're not really talking to a hacker's website instead.
The most common asymmetric cryptography system is RSA, which uses math involving factoring large numbers. It's hard to “break” RSA (decrypt a message without the appropriate key) because as far as we know it's hard to factor large numbers. However, we know that a sufficiently powerful quantum computer could easily factor large numbers and thus break RSA.
Certain mathematical problems involving structures called “lattices” are believed to be hard to solve, even on a quantum computer. New cryptographic systems have been devised that rely on lattice problems to ensure security instead of integer factorization. These systems, or systems like them, could someday supplant existing asymmetric systems like RSA if it looks like quantum computing will be a practical reality. | 47 | 83 |
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ELI5: How does economics remain reliable even though it was founded on the principle of the rational consumer? | Obviously now we have things like behavioral economics that try and negate this problem by adapting to human behavior, but how did the field have any accuracy and credibility before that? The idea that all consumer decisions are rational is absurd, especially considering how capitalism functions and the fact that irrationality can cause both economic successes and downfalls. | The axioms that constitute rationality:
* given a choice between A and B, a person can say which they prefer or if they are indifferent
* if they prefer A to B and B to C, they prefer A to C
Are not actually all that demanding. They are fulfilled in the vast majority of decision making contexts or are close enough to fulfilled that it doesn't matter.
If you want to poke a bigger hole in the conclusions of most economic models, ask their authors' about how realistic their assumptions about information are.
That said, an imperfect model is vastly preferable to no model. Economic models have been vastly important in correctly justifying countless policies. | 32 | 34 |
ELI5: How is cancer so deadly but a person feels fine one day then the next they are told they have 4 months to live? | Exponential growth. At first cancer is a single malformed cell dividing without restrictions. That 1 turns into 2, 2 becomes 4, 4 becomes 8, 8 turns into 16, etc. With each division the number of cancerous cells doubles. (More or less)
So for the first few months or so the cancer is only a minor disruption, but soon it rapidly becomes larger and larger and starts affecting the function of the entire organ and body. Taking up nutrients and putting stress on other organs causing cascading organ failures if left untreated. | 8,084 | 9,998 |
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What happens when you boil an acidic solution? | I was making tomato paste the other day and I noticed that the recipe didn't suggest I add lemon juice or citric acid. This got me thinking. When you boil down a liquid that is slightly acidic (boil off the water in the case of tomato paste), how is the PH affected? Does it become more acidic? Less? Stay the same? | That depends on the relative vapor pressure of the acid in question, compared to water.
If it has a higher "relative volatility" than water, the acid will evaporate and boil much faster than the water will, thus reducing the concentration of the acid. However the acid fumes can be captured and condensed using a distilling apparatus designed to handle acids, thus producing a more concentrated acid.
If the acid has a lower vapor pressure than water, the water will tend to evaporate and boil much faster than the acid, thus concentrating it. this can be done with sulfuric acid. Though for technical reasons it's difficult to concentrate H2SO4 over 90% this way. | 19 | 67 |
CMV: I believe most science and stats regarding gender nonconformist are manipulated and pseudoscience. | I believe most science and stats regarding gender nonconformist are manipulated and pseudoscience. Not only on the anti side but also on the pro side
The reason I believe this is because gender is a “social construct” therefore, unless manipulated by an outside force, it shouldn’t have an inherent effect on the brain. Therefore the brain composition is largely dictated by a persons sex. Yet in an article I was reading it says:
>“When we look at the transgender brain, we see that the brain resembles the gender that the person identifies as,” Dr. Altinay says. For example, a person who is born with a penis but ends up identifying as a female often actually has some of the structural characteristics of a “female” brain.
>https://health.clevelandclinic.org/research-on-the-transgender-brain-what-you-should-know/amp/
Now there a couple issue with this. For one a person doesn’t “identify” as a male or female this is dictated by your chromosomes. The second is that if gender is an social construct how can someone who identifies as a different gender have a brain that is closer to someone of that gender if gender is an abstract social construct that changes over time?
As well if people can be trans without dysphoria then that would mean being trans is in fact a conscious choice someone could make.
Additionally, I feel like there’s a lack of stats and the ones available aren’t considered in a genuine way are sometimes rely on ignoring certain aspects of them. For example the skeptism of transwomen in ciswomens spaces. While yes transwomen are women, they are also male and thus part of male statistics. People don’t have an issue saying Men(Males) commit most of the crime but do not acknowledge that transwomen would be apart of this statistic (at least in the US) because these stats are tracked by sex not gender. Additionally, a small study found that in terms of violent crime transwomen criminality does not significantly change from that of cismen and that transmen criminality increases from that of ciswomen.
Now I get why people would do this. Transpeople are people like anyone else and just like other people, I don’t think it’s fair to use statistics to discriminate against any particular individual. But I also do not think it is fair to establish policies and laws, based on manipulated and bias information
Cmv | This is pretty straightforward. Social constructs have real impacts.
A poor person’s brain is likely going to be noticeably different than a rich person’s. Money is a construct. That doesn’t mean growing up in a society that really does respect that construct means it doesn’t have real impacts.
Moreover, you seem to be confusing *gender* which is a construct built atop sex with *gender identity* and sex. You’ve claimed both that gender is a construct and that it’s determined by chromosomes. Then you applied this to identity and claimed people don’t have them. That doesn’t make sense. Have you even done a DNA test before identifying someone by their gender? | 113 | 34 |
ELI5 how is the US banking system not crippled by credit card fraud? | I come from a country where most people don't have a credit card.
I cannot wrap my head around [this](https://m.youtube.com/watch?v=vmh3_nSR1jU) documentary.
Now I get that credit card fraud *is* a big problem.
But if all you need is the card number to order stuff, and card numbers are so easy to come by as shown in the documentary, then why is not every single criminal in the US running a credit card fraud operation?
It seems super easy and low risk. Get a burner device, order stuff from public wifi, and don't be stupid about the delivery locations. | While credit card fraud is a problem, it’s not overwhelming to banks.
Just like stores expect some shoplifting and include the costs of that in their prices, banks expect some fraud and include those costs in the fees they charge.
Banks also have lots of ways to detect fraud, and can often catch it before there are too many charges. They have algorithms that look for charges outside a customer’s normal area, at places they don’t normally shop, etc. When I’ve had a fraudulent charge, the bank itself has always been the one to catch it and call me.
Also, you need more than a credit card number to shop. In person, you need the card itself. If a store runs just the number off a piece of paper, they would be liable for the charges. Spoofing cards is harder, especially the new chip cards. Online, you typically need the security number from the back of the card and the billing address. You can buy full sets of stolen data, of course, but it’s harder than straight numbers.
As to why every criminal in America doesn’t take up credit card fraud, on the whole a lot of crime is opportunistic rather than carefully planned. Someone needs money *now*, so they smash a window or bump key a door, grab some stuff, and leave. Or rob someone in person. Credit card fraud takes start-up capital (to buy the devices and numbers), planning, and patience. | 497 | 551 |
ELI5: The new "Unlocking cell phone law." | To understand the new law, you need to understand what the law was. So first some history.
In 1998 the U.S government passed the Digital Millennium Copyright Act (DMCA, the same thing you see if you see a takedown notice on Youtube or Google). Included in that (in addition to the copyright provisions themselves) was a prohibition on circumventing what are called "Digital Rights Management." In laymen's terms it's a bit like both making it illegal to take your television *and* making it illegal to break your door lock in an attempt to get your television.
The DMCA gave the librarian of Congress the power to exempt certain things from DMCA regulations. Basically, he could say "so, yeah, rooting your iPhone *is* a circumvention, but all it's doing is letting people use their phones to their fullest capacity, so we're going to exempt it" (which actually happened).
The issue of cell phone unlocking came up, and the Librarian of Congress elected *not* to exempt it. But did provide a window for people to unlock their existing phones without running afoul of the DMCA. The idea was that while it made sense that anyone buying a new phone could simply buy an unlocked version, it wasn't fair to stop people who got their phones prior to the rule coming down from unlocking them.
So, about a year ago, that grace period ended and it became illegal (under the DMCA) to unlock a cell phone. Recently, Congress passed legislation to amend the DMCA to exempt cell phone unlocking. | 14 | 71 |
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What is 'information' in the quantum physics sense and how is the idea of conservation of information a valid law when I can think of several examples of where information is lost? | In quantum mechanics, the fundamental entity you work with is the wave function. It's the wave function that encodes everything there is to know about the system. In that sense, the wave function is information about the system.
Now, quantum mechanics tells you how wave functions evolve over time, we call this a unitary evolution. That's somewhat technical, but in essence it means that the information encoded in the wave function never gets lost, whatever happens.
However, as you object, there seem to be cases in our experience where information seems to be destroyed. Say, you have a piece of paper with a secret code on it. If you throw it in the fire, that information is lost. How does that compute with what we said before?
Well, quantum mechanics still maintains that that information is conserved. The information is now encoded into the ashes, into the heat, etc... The thing is, it is practically irretrievable to us, so to us it seems lost. But in actuality, it is still there and someone with perfect control of all aspects of that situation could in theory reverse the process and recreate the piece of paper, or find the information back in the way the ashes are disposed and the heat of the fire dispersed. | 31 | 119 |
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CMV: Often times, when a person gives an advice to avoid danger, this person is not "victim blaming" | We all heard something similar like this before. A person is the victim of a crime and another person starts saying how the victim could have avoided it by doing (or not doing) something.
Yes, It's quite scummy to throw the blame on the person who was the victim of a crime. Nobody sane would ask to be hurt or worse. However, there's two big problems that simply cannot be fixed no matter what:
1)The state cannot protect their people.
2)Crimes will exist forever, no matter what.
For the first point keep in mind that most of the police work is reactive, not preventive. Most of police work is to find the criminal AFTER the damage is done and punish the culprit. The police does have a preventive aspect to it, but it's mostly to scare the most cowardly criminals (those who simply are too afraid of being caught and go to jail) or when the police go on patrols.
The only possible way for the police to be fully preventive would be if there was at least 1 cop on every street of every city. But, this is simply not possible. Not only it would requere thousands (if not millions, depending on the size of the country) new police officers, but there's also the matter of the cost of training, gear and salaries. Not to mention that being watched 24/7 by the police also causes a problem on its own and people will think they're in an orwellian dystopia.
As for the second point, crimes exist no matter how developed or educated a nation is. However, education does play a big role in the reduction (keep in mind this word, it's important) of crime. When a nation has a good educational system, people have a bigger chance at getting good jobs and rising out of poverty and crime.
But not every crime is related to social status. Lots of educated and rich people commit crimes as well. However, the crimes related to people stealing from others to survive would certainly decrease by a lot.
The problem lies on the fact that some people think that educating people to reduce crimes is about putting a bunch of adults in a room and saying "did you know that...crime X...is baaaaad?"
You'll get pretty much three reaction out of this:
1)"Why are you talking to me like a toddler? I already know that. Fuck you for wasting my time and treating me like a crimnal when I've done nothing wrong!"
2)"Like I fucking care. I already know that doing crime X is bad. every adult in the existence knows that. I'll do it again and again and maybe even to you."
3)"I didn't know that crime X was bad. This is interesting." - if you, as an adult, don't know that causing pain, harm, humiliation, trauma and/or death is bad than you have bigger problems in your head.
So, doing this^ kind of classes is actually pointless and serve no purpose other than pat youraself on the back.
Also, even if a nation suddenly declares that every single crime (not matter what) would be punished with death, crimes would still exist. There would be people who honestly think that they can get away with it and maybe pin the blame on someone else and there would be people who don't care about the consequences of their actions as long as they get to commit the cirme they want to.
So, with all this in mind, what can we possibly do? Imagine the following example:
Two men, who are dressed similarly, are walking alone, each on a different crosswalk. Both have 1.000 dollars. One has 100 in the wallet and the rest is hidden inside of his sock while the other is holding all the cash on his hands. Then a thief passes by and spots both of them. Which do you think that the thief will target? Who do you think it's the easier target? Does this mean that it's the fault of the man for holding the money? Does he deserve to be robbed? Of course not. Now, what if both had 100 dollars in the wallet (because some thieves can get very violent when they get nothing out of a robbery attempt) and the rest hidden in their socks. The thief might deem either of the man not worth the trouble from the looks or the thief might try to steal from any of them.
And this is the heart of the issue, the best you can do is REDUCE the likelyhood of a crime being commited to you. No advice is 100% failproof.
How about learning self defense, like martial arts? It's a good thing, but doesn't help much when the opponent has a gun (unless the criminal gets distracted and you are within range to disarm the criminal). Same issue if you have a gun or some kind of weapon (like a taser or pepper spray). The criminal will not sit and wait for you to draw your own weapon.
You also can't ask the criminal to stop attacking you and wait for you to call the police and ask the criminal to patiently wait on the place for the cops to arrive and arrest him/her.
In the end, sadly, it's only up to you and you alone to protect yourself by reducing the chances of being a victim of a crime.
So, next time you hear someone saying "don't go out alone in the dark", don't read it as "you're blaming me???".
But read it as "you shouldn't play with your luck so much, bad people won't care if you're hurt. Try reduce the chances of being harmed."
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> *This is a footnote from the CMV moderators. We'd like to remind you of a couple of things. Firstly, please* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | What reaction are you hoping to have from providing safety tips? Are you really under the impression that the local news could do a good enough job getting the message out that "Walking in dark allies in bad neighborhoods at night is dangerous" and get people to change their behavior which would result in a reduction of crime? That seems almost as absurd as your other example of trying to train people that crime is bad.
> Crimes will exist forever, no matter what.
See, this is the exact problem. Don't just throw your hands up and say, "Guess we can't do anything about crime except try to get the message out to our poor young women to not wear such short skirts". You have a microphone and an audience and you spend that time focusing on making sure the good citizens are properly scared of bad neighborhoods instead of pushing for things that might do a much better job of addressing the issue.
> For the first point keep in mind that most of the police work is reactive, not preventive.
You're thinking too narrowly. The state has a lot of ways to reduce crime even outside of just the police. Things like installing better lights in areas. Doing a good job of keeping lead out of the water. Removing blighted buildings. Behavior intervention programs and other education programs that have been *shown scientifically* to have a meaningful impact on crime. | 123 | 796 |
How do Magic Eye pictures work? | It has to do with how your eyes focus. To understand, start by holding one finger right in front of your face, at eye level. Hold your other hand at arms' length behind it. When you focus on the finger in front of your face, you will notice that you see double of the hand far away. Similarly, when you focus on the hand, you'll see double of the finger.
This is because you have two eyes. They can't both point at close objects without skewing their perspective on further objects, and vice versa. Think of lasers shooting out from your eyes, the object you're focussing on being where they cross each other. So looking at your finger, they cross close, like this X. Looking at your far hand, they cross much further away, like this /\.
After a bit of practice, you may be able to focus your eyes for nearer or further *without* using your hands or other objects. But it is much easier to do it with something there because we're used to looking at concrete things, instead of just focusing on an area somewhere in front of us.
Magic Eye pictures trick our eyes into seeing perspective that isn't really there by having those patterns that repeat over and over across the page, but slightly differently. For a very simple version that doesn't have any hidden pictures, try to focus these two x's into the same place.
X X
If you do it right, it will look like 3 x's. Two blurry ones on the sides, and one more clearly defined in the middle. Because the images going into your right eye vs. your left eye are a little bit skewed in their respective directions, when you cross your eyes to focus on the patterns in a Magic Eye, it appears to be 3D. | 12 | 35 |
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[Star Wars VII] Why aren't the wrecked Star Destroyers entirely salvaged? | Most of the useful stuff is. Hull plating and duct work aren't that valuable, but functioning electronics and power systems can at least be worth some modicum of effort.
What you see is, for the most part, just the skeleton with all the worthwhile bits torn out. | 42 | 37 |
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eli5: how come when your organs are in your body, they need to be 98 degrees, but in an organ transplant the organ is cooled? | So you're comparing a state in which an organ needs to be actively working to a state where it should not be actively working.
So normally, organs have an ideal temperature that they "work" at. There's a lot of reasons for this from enzymes, biochemical reactions, etc. to amount of blood required to deliver oxygen for these organs to continue functioning, all which are temperature sensitive.
When you are taking organs out of the body, you are depriving them of blood (and thus oxygen) to carry out all of these metabolic functions. The cells in these organs will slowly start to accumulate waste products, break down, and die as they try to continue these metabolic and chemical reactions without oxygen.
What freezing does is slows down these chemical reactions almost to a halt. Enzymes, proteins, reactions require energy (usually in the form of heat) to work. This reduces the requirement of oxygen and lets organs become viable for a lot longer outside of the body without a blood supply. | 268 | 287 |
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Why are cardiac valves from pigs not rejected by human bodies? | The problem with the body rejecting organs/tissues is huge and mostly entails the usage of pharmaceuticals preventing the rejection. Why can be transplant cardiac valves from pigs without having a rejection (in most cases)? | Roughly speaking, all tissue in your body has cells (which are alive) and other things (which aren't). Some tissue (like muscles) has a lot of cells and a little of other things. Some tissue (like cartilage) has very few cells and is mostly made of other things.
Immune reactions primarily target living tissue.
Heart valves are made of is almost entirely non-living tissue, and after being harvested from pigs, those valves are treated with chemicals to kill off any residual pig cells. As a result, when they are implanted, they usually do not cause immune reactions because there are no cells within them to cause an immune reaction.
This is similar to receiving ligament grafts from deceased human donors. | 15 | 25 |
Does the universe have a non-zero angular momentum? | Does the universe spin? Is this a question which even makes sense? Do we even know / have any way to ever find out? | There's a set of common assumptions made in cosmology that the universe is (on reasonably large scales) homogeneous and isotropic. Homogeneous means that every large patch of the universe looks roughly the same, regardless of where the patch is. Isotropic means that there's no preferred direction.
There's no inherent reason to make these assumptions other than they make math easy. But it would be weird if, for example, the universe had a preferred "center." It would raise questions like "why there? Why not anywhere else?"
And since we haven't seen any evidence to disprove these assumptions, for the time being it's probably safe to continue assuming them. | 25 | 21 |
ELI5: What is the difference between a good lawyer and the "best lawyers money can get you" while defending you in a case? | To put it simply as thus:
A good lawyer works within the law to get you the best result possible. They work with the system, and don't break the rules, and so are good all round.
The best lawyer money can buy, however, is one who knows when, where, and how the rules can be bent. They know how far the rules can be bent, and which rules can be bent in which situation. And thus, they are able to get a much more favourable outcome that the good lawyer can provide, albeit at a high cost.
In addition to this, the best laywers are very specialised in what they do. A top end laywer who defends you in a murder case, for example, may have spent their entire career studying the criminal laws for murder, and cases where the rules have been bent, both successfully and unsuccessfully, and what results came out of it. If you hired this lawyer then, to defend a libel case, or a common dispute, they wouldn't be as good as a different top end laywer who has studied these cases.
Think of it like surgeons. Most surgeons are good all round, and they can deal with most types of surgery, with no issues. But for specific and technical surgeries, like organ transplantation, brain surgery, or reconstructive surgery, a regular surgeon is not going to cut it, and you need to hire a specialist to get the job done the best.
EDIT: Further clarification. | 43 | 20 |
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CMV: Immigrating to the US should be way easier than it is now. | I genuinely can't wrap my head around how immigrating to the US is so regulated and strict. I understand doing checks to ensure the safety of the public, but I don't understand how moving here and getting accepted into the country is so hard. Like how can moving where you live be illegal...
&#x200B;
And any reason should be a solid justification for immigrating to another country -- seeking refuge from persecution/danger, financial costs, job opportunities, access to education, quality of life, or even a reason as simple as just wanting to move (as people do all the time). Can someone please explain to me the reasons why people are denied access into the US, why people seeking refuge from danger and poverty are put in border detention centers, why simply moving to a different country is such a burden and viewed as a crime? It seems like people move from the US to Europe all the time, and it's seen as totally okay, but immigrating from Mexico to the US is a totally different story -- why???? | Immigration is a privileged. There is no reason any country has to allow any non-citizen enter its borders let alone reside or become a citizen. None. Want a good example - Canada denies visa's to people with DUI's. (it a little more complicated than a simple no but that is the default answer)
Countries allow immigration because it can be a net benefit. Since countries doing this are looking for a benefit - it should be obvious that well off citizens from western nations would have easier time than those in poverty.
And lastly - the US has some of the most LAX immigration rules in the world. Try looking up immigration rules to Europe from outside the EU or even Canada. | 23 | 25 |
ELI5 What is bankruptcy and how does it work? | It's a formal declaration to the courts that you [as a business or individual] are in a situation where you have more debt than you are able to pay off (under the current terms of the loans/etc) and that you are seeking protection from the courts to remedy the situation.
The overall idea is that bankruptcy protections are in place so that overwhelming debt loads don't permanently cripple someone: instead we give a "second chance" of sorts
The courts will often force the sale of non-essential assets and use any available funds to repay what can be paid, and discharge the rest. Alternatively, the repayment terms of any debt may be modified to be more favorable to the debtor. | 18 | 22 |
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Would there be a benefit to putting solar panels above the atmosphere? | So to the best of my knowledge, here is my question. The energy output by the sun is decreased by traveling theough the atmosphere. Would there be any benefit to using planes or balloons to collect the energy from the sun in power cells using solar panels above the majority of the atmosphere where it could be a higher output? Or, would the energy used to get them up there outweigh the difference from placing them on the earth's surface? | The atmosphere is largely transparent to visible light, which is the range most conventional photovoltaics use. If located higher there could be a marginal increase (ignoring other factors at the moment) because there would be a few percent more of that light, however without the atmosphere blocking the more energetic wavelengths like UV the cells degrade requiring you to add thicker shielding/glass to mimic the effect of the atmosphere.
Additionally photovoltaics have a reduced efficiency when hot, which is a concern when they are being hit by useless wavelengths (which normally the atmosphere blocks) that only heat the panels and contribute nothing to the actual generation of power while also having very little to no medium to assist in transferring that heat away
Finally you'd need a way to get that power from the panels back down to the ground, which could be done in a variety of ways, but realistically it's not practical from an engineering or cost perspective when you want the power at ground level in the first place. | 1,372 | 4,120 |
[Harry Potter] Do non-verbal spells still require some sort of hand or wand movement? | Like if I somehow tied up Voldemort and gagged him would I still be susceptible to spells from him? | It depends on the skill and magical merit.
Expert tier wizards can both *wandlessly* and *non-verbally* cast spells, but it takes a lot of mental willpower and multitask abilities, which is why non-verbal magic is not taught until 6th year in Hogwarts.
For instance, during the duel between Dumbledore and Voldemort, he casted a Fiendfyre and manipulated it into a giant serpent. He did it non-verbally and wandlessly. And Fiendfyre is one of the most difficult, elaborate and delicate curses that exist, hell, Hermione was afraid to cast the curse (even though it's one of the few spells which can destroy a Horcrux). That alone demonstrates the apex of Voldemort's powers.
Yes, it's possible to not make any hand movements or use a wand at all. African wizarding school also teaches wandless magic use more prominently than Hogwarts, as a wand was an European invention. | 53 | 59 |
ELI5: What biologically prevents interspecies breeding? | I remember learning in Biology that different species could not create offspring. That seems to be counteracted by mules with horses and donkeys. How does the reproductive system determine that there's another species involved and prevent insemination?
Ex: If that same horse from earlier got drunk at a barn party and went home with a cow, how does nature prevent them from making some weird hybrid horse-cow (a corse if you will) baby, and why didn't that same system prevent the mule from being born? | Two different obstacles to interspecies breeding.
One is physical, where the sperm dies before it can reach the egg, due to different chemical environments in the uterues, or simply cannot reach the egg.
The other is genetic, where either each animal has a different number of chromosones, so the genetic information from the father can't find a suitable match with the information from the mother. | 41 | 75 |
[Scooby Doo] Why did nobody ever bring a gun? | Seems like most problems the gang faces could be solved rather easily with a gun | While they could claim self defense in many of these cases, the fact that they are going out searching for situations while armed would violate multiple laws, from laws against vigilantism to murder. Also they are hippies and likely against such direct violence. | 35 | 16 |
ELI5:Why did Nicola's Tesla theory of Clean Energy never got developed, did it lack scientific credibility? | I have been reading lately about this matter on the internet and different books I found, and from what I see it was a theory of huge potential, that never got scientifically rejected but simply died away with time and other methods were developed further.
Is it possible that we are ignoring something so valuable? | Nikola Tesla had a lot of unusual ideas, some of which were more practical than others. For example, he did not believe in radio waves. Although he made some important advances in electrical engineering, a lot of his claims were never technically demonstrated or explained in a cohesive way. Without any known principles to be tested, those claims don't really have any use. What specific idea did you have in mind? | 37 | 37 |
CMV: I believe toll roads are bad and just another tax for what our government should already be providing. | It seems every city has them or wants them, and even when its proposed to only last a few years, they somehow keep running cause the free money is good. Sure, some of them are well maintained, but aren't all of our roads supposed to be well maintained? Toll roads basically tell us only those who can afford to pay to drive get quality roads that our government is supposed to provide anyways.
And for the most part, private corporations are the ones that end up getting a good deal out of the projects while we get shafted. If our legislators need money to improve our roads, shouldn't they be upfront about it and tell us how they plan on doing so? But even then, it seems like people are somehow ok with toll roads and understand the costs that are needed. Yet, when other taxes are proposed, people get up in arms because the word 'tax' was used as a way to improve things.
Why isn't this issue brought up more often?
Change my view reddit! | Two benefits to having a toll: 1) The people who use it are the ones who help to pay for it, and 2) Gives people an incentive to not use it if they can avoid it, thereby reducing congestion.
It's similar to paying a fare when you ride the bus or the subway. | 13 | 20 |
ELI5 - why do data breaches cost millions of dollars? | There are a combination of reasons that combine to result in those numbers.
Depending on what nation the company is in, there are regulatory penalties that can be applied if its shown the company didn't take required precautions to protect the information.
There are potential civil law suits from the people affected by the breach.
There is a loss of business after a breach too. Customers are less likely to do business if they are worried their information is at risk. Other companies become more reluctant becuase they don't want the association.
All of these factors can result in significant financial loss to companies that experience data breaches. | 2,827 | 3,594 |
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ELI5: How do they find who is patient zero? | Epidemiologists study these things. They carefully take a patient's history, their location, the people they've interacted with, etc. After they've done gathering pertinent data, an analysis is done to highlight common denominators. It's like detective work trying to narrow down things to get to a point. | 1,341 | 2,398 |
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CMV: If society thinks a 35 year old man is wrong for wanting, and trying, to have sex with a 17 year old girl, society is based on lies | To clarify: Are you under the impression that all other societal constructs are *not* merely a hodgepodge of cultural norms intended to keep us all from killing eachother?
Society isn't "based on lies" because of one particular instance of hypocrisy, society *is* a bunch of lies we tell ourselves because the cold truth of our bestial nature means we'd never get anywhere without it. | 564 | 1,092 |
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ELI5: Why charities with similar goals don't merge to become more effective? | I saw today on my Facebook newsfeed of a video for I already forgot the name but a charity that provides clean drinking water to poor villages in Africa.
I am all for the cause because everyone in the world should have clean water at a bare minimum. That said, I know I have seen at least 2 other charities with the same goal.
Why do these charities not merge, combine funds and resources, and provide more marketing campaigns and build more wells?
The only thing that comes to mind is el hefe of each charity wants his final say in how things are done and/or some want to push their agenda (be it a political/religious/etc affiliation). Please tell me it is not that ignorant? There has to be more reasons, right? | Merging companies (and yes, non-profits are companies) requires a lot of work. First, just because two companies do the same thing does not mean that they could merge easily. What if one is a Catholic charity, and the other is non-religious? Is the new charity religious or not? Which of the two Presidents is going to be in charge? Are you going to fire a bunch of staff? If not, how is it more efficient to have 1 big company with twice as many workers?
Companies merge when it makes some financial sense. Since non-profits are not in it to maximize value, they don't have to worry about being the biggest and best. | 28 | 117 |
ELI5: why is it a good idea to talk to children like an adult | Children treated with respect, expectations, dignity, and presented with matter-of-factness of the challenges of everyday life become adjusted to them faster, learn faster, get ahead in school and in life faster, and stand alone as whole adults when they grow up.
Kids who have to waste time and resources trying to figure out why their parents are babbling nonsense at them, or who no longer seem to care about them since they're no longer behaving in an infantile manner, face a choice between acting out a masquerade for the sake of their parents' egotistical preferences, or losing parental support (or worse, facing parental condemnation) for developing as humans.
TL;DR: What kind of eighteen-year-old do you want? Kids aren't props nor property. Train a human being, not a babydoll. | 44 | 24 |
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ELI5: Why can I eat raw fish but not raw chicken or pork? | Also, the same for undercooked beef. | Chicken and pork are more likely to be contaminated with the sort of bacteria and parasites that are harmful to humans. This is partially due to the conditions they are raised and slaughtered in, partially due to the biological similarity between certain animals and humans, partially due to how long the meat is left to 'hang' and age to let the blood run out/flavour develop.
If you raised a pig in sterile conditions and spent the money to know that it was completely disease and infection free, you could eat the resulting pork raw safely if you wanted. It's just a lot cheaper, easier and tastier to cook it. | 68 | 124 |
ELI5: What are the differences between blood types? | There are slight differences in red blood cells that determine blood types. If you have certain differences, then your immune system learns when you're an infant not to attack those cells because they're not foreign invaders. But if you don't have them, and you get a blood transfusion from someone else who does, then your immune system that's never been exposed to those will think it's a foreign invader and attack it, which will result in a dangerous and possibly deadly reaction.
Type O don't have any of these, so they can only receive other type O blood. Type AB has both (in what's called the ABO group) and can receive any blood. Types A and B have one or the other. There's also the Rh group, which is where the + and - come in. If you're + you can receive both + and -, but if you're - you can only receive other -.
There are actually 33 blood group systems that have been identified, but the ABO and Rh are the two most important. The others don't result in too many severe complications. | 11 | 15 |
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ELI5:Why do shadows tend to be attracted by other shadows ? | I was in the bus today and whenever my shadow got close to another one, it would stretch to reach the other. I never paid much attention to it before now. I know it probably is something about light, but I'd like to know the exact reason of this phenomenon. | Imagine two equally tall mounds of sand on a flat surface.
Now, push the two mounds towards each other. You will notice that where the two mounds touch, the sand will combine and rise higher.
The same occurs for shadows. A shadow's edge is never completely sharp due to diffraction, a property of light that blurs the edges. The farther away the shadow is from the object blocking the light, the more blurred the edges become.
When two shadows come close together, in the overlapping regions, the light gets blocked twice, once by each shadow. The amount of light blocked must be considered separately per shadow. Imagine that the blurred part each blocks 50% of light. Then one shadow allows 50% of the light through and the second shadow blocks 50% of that. Therefore, the total blocking is 75% which is why it appears darker than each individual shadow, much like how the sand in the two mounds rises higher than the original mounds as the mounds come closer and closer. | 19 | 21 |
CMV: People need to stop and think before arguing about terminology/semantics | I think it’s a flaw of CMV and also logic in general. This train of though started by reading a lot of the online debates about the term “concentration camps.” I think the debate is relatively absurd for a variety of reasons on both sides. First of all, no matter what you call them the realities within them are the same. Secondly, I think it’s severely intellectually disingenuous to argue about terminology when you hold a strong underlying belief that you are trying to prove by using certain terminology. More than this we often lose sight of reality when arguing terminology.
For a relatively absurd example, let’s say you(a liberal) and me (a conservative) watch a video of ISIS beheading someone. I say “wow that’s really what radical Islam has done to the Middle East” and you say “wow that’s a disgusting example of what religion does to people.” We then go on to debate whether or not calling ISIS “radical Islamists” is really the appropriate term and whether or not I am a bigot or something else. Despite this, I clearly felt empathy for the people who were killed and these people were likely Muslim.
Lost in this is someone just had there fucking head chopped off and I the conservative felt empathy toward them. This is a huge point in my opinion. Yet, if someone corrects my terminology I might feel far less empathy.
Now that’s how I feel looking at American politics. When you break it down, people often agree on many things. It’s horrible that nearly a murder a day happens in Chicago or Baltimore. We want the kids to have better opportunities. Yet, we let terminology override our common sensibility and if a conservative calls something “ghetto” we get in a froth. We use words that we know the other side will hate and the reject words that they use for various reasons. Now words are powerful and are the root of meaning and they do have historical context. Yet sometimes to change someone’s mind I firmly believe that you need to accept some of how they define the terms in question and look for common ground. I’m not rejecting debates of semantics, meaning or definition but merely saying that they can be counterproductive when people have heavily ingrained definitions.
I will give out a delta for someone who gives examples where appreciable good has been done in changing a persons opinions by question the definition of a word that they were using. Thanks in advance for your responses.
Edit: I’m speaking about American politics, and polarizing issues in general where the mere usage of word might trigger such a negative reaction by one side that will result in the conversation not being resolved. A better example is the term “privilege.” In America, conservatives hate his word when it is used to describe advantages based on unchangeable factors such as parent money, race, etc. I have personally convinced conservatives to acknowledge advantages that are not a result of individual hard work and based on race, class, sexuality by never mentioning the word privilege. I’m not arguing semantics aren’t important, so maybe my title is disingenuous but merely we need to consider whether or not arguing over a specific word is the best way to find common ground and change opinions.
Edit p2: Seems like some people construe my post as condoning hate speech. Again I’m taking an intentionally vague stance on this. I’m saying “people need to think” about arguments about semantics instead of “people should never.” When conversing with an individual you need to decide if it’s best to use certain words that may offend them or whether or not it’s possible to change the definitions they use. In some cases it may be possible to get them to see the point without changing the definition. This is a separate instance, imo, from the use of retard or faggot because the individual using that word has a clear negative intent. The term “radical Islamist” probably has some negative intent behind it in my example, yet I’m stating that the conservatives empathy toward the individual killed may be the more relevant starting point for the discussing that the terminology.
Edit p3: My view has changed fam. I think it’s very important to be careful when discussing generalization like this because in some instances the speech itself can be indirectly or directly very harmful to a certain group. Arguing about words may be beneficial even if views are shared if the words used are extremely offensive and or negative. Thanks for the responses. | Okay — so when two people fundamentally disagree over whether a term is appropriate how should they resolve their dispute?
I think rational discourse is exactly the right way to resolve disputes like this. It's how you find out what exactly people mean by the terms they use. It's a peaceful resolution that gives both sides a chance to get at the underlying issues present yet hidden by semantics. And in general, is the only productive way to resolve disagreement. | 16 | 58 |
Are ancient Rome and ancient Greece over-rated and over-adveritised in terms of their legacies, glory and merit | I know that this sounds like a weird question but I posted this question a few weeks ago and was told that it is better suited for sociologists to answer so I decided to give it a try
I want to say that I am not actually implying that ancient Greece and ancient Rome are not what one would define as "great" or "glorious" because there are some things that would definetely attract any person to what these ancient civilisations were regardless of how they are interpreted as in history books or fictional works. There is a certain "magic" or awe towards these civilisations and I too have my own appreciation and sometimes even romanticism and gratitude to these civilisations and how their achievements and legacies were kept intact and eventually been passed on through generations or even adapted to even more refined technologies and methodologies like astronomy, mathematics, art, philosophy and so on.
But I sometimes feel like these two civilisations are often way over-glorified, or at least the popular conception of ancient Greece and ancient Rome are over-saturated which gives the impression that other civilisations were petty or miniscule in comparison or that these civilisations did not have their own flaws and even horrors.
One thing that stood out to me in particular when I found out that the Persian Empire was not as horrificly imperialistic and authoritarian as I was told it was, especially when I saw the film 300. Therefore, after I learned about this, I decided to look into the Persian empire, from its history, system of government, mythology and so on, and was amazed and filled with awe. Something that impressed me was how the Persian Empire had its own version of road construction even before the Roman Empire and its system of government and bureacracy was very structured and had its own benefits such as religious tolerance and women's rights (or at least we view them with a positive view from the perspective of the 21st Century) and this was mostly found during the reign of Cyrus whom I remember that I was taught that he was a ruthless leader. What suprises me the most was when I learned that Alexander wanted to implement the Persian's governmental structure in his empire when he managed to conquer the entire Persian empire even though the Hellenistic empire was short lived.
On the other hand, when I learned more about the Greeks and its own customs and social structures, while I still have my own sense of awe and do feel the presence of the ancient Greek "magic" when I read about them, I am surprised on how the ancient customs of ancient Greece are often neglected or not that well-known. For example Athens is seen as the birthplace of democracy but Athenian version of democracy was more limited and did not include women, slaves or even blacks as racism also existed during that time (even though the Hellenisitc empire of Alexander eventually integrated with other civilisations with other ethnicities like ancient Egypt which had inhabitants with darker skin colour) and the pseudo-science of scientific racism was also used to justify or rationalise that mentality. Even Athens had its own form of "imperialism" especially during the Peloponnesian War against the city-state of Sparta which is ironic and I also learned how the glorification of Sparta is also over-exaggarated as it was a eugenic city-state and the Spartans were a leisure-class and Sparta's social structure was a strict monarchy with plenty of slaves doing the hard work while Spartans focused more on military work or leisure. I also learned that the Spartans were not that unique or exemplary when it came to military structure or strategy and mostly got its glory and fame after the Battle of Thermopylae.
Even the Roman Empire has its own versions of not-so-well-known drawbacks even though I still admire the Roman Empire to this day. Apart that the conflict between the corrupt Roman Republic and the more ambitious and possbly tyrannical Caesar is still one of the most well-known debates as to there is no clear answer on how was the hero or the villian of the story, many people throughout history often glorified the Roman Empire and wanted to mimic it or copy it with meticulous precision, whether it is its symbology like the Aquila and the American Eagle, the fasces and its influence on fascism and the fasces symbol is also found in the US Capitol, the ideology and structure of Republicanism, the attempt to make the Roman Empire a thing again after its collapse (at least, the Western side of the Roman Empire as the Eastern side was still intact for another 1000 years) such the Holy Roman Empire, the German Empire where the Emperor's title was the Kaiser (a German interpretation of Caesar) and the Russian Empire with the king/emperor's title was known as the Tzar (the Russian version of the word "Caesar").
Many times I was told on how effective the Romans were in their military strategy and while that was indeed true, most of its military glory was found during the late-Roman Republic and early-to-mid Roman Empire era and most of its structure was more complicated to handle as when the Roman Republic became an empire, there were conflicts on who had the authority to be emperor (like even Nero's mother killed her own husband so that Nero would be emperor even though she still wanted to have a say on his choices or when the successive emperors of Rome durign the period of the four Emperors were supposedly killed); there was a difficult time during Roman History called the Crisis of the Third Century where the Roman Empire had to battle against conflict enemies and sometimes had gone through internal struggles where the Emperors were killed by their own legionnaires (but the same time, the Roman Empire managed to persevere a bit longer with the formation of the Roman Tetrarchy even though still had problems)
I could think of many more but I also even realise how these two civilisations were not that grandiose in terms of glory and achievement and even other civilisations had their own "glorious achievements" or structures that make them revered and worth reading about such as ancient Egypt, ancient China (despite that ancient China had also its own recurring pattern of constant reformations and overthrowing its own kingdoms and empires), the Celtic people, the Slavics, the Jews, the Muslims, the Byzantine Empire, the Mali Empire and so on. | Remember that much of what we call modern academic history has its roots in nineteenth-century Western nation building. This was a process informed not only by US/European politics but by the early conquests in the Americas and Asia, the late-nineteenth century scramble for empire, the scientific and industrial revolution, scientific racism and eugenics, and etc.
Central to this time is the idea that Progress and that history has a direction. The early historical profession looked to Greece and Rome as Europe's antecedents, understanding their supremacy as prelude to, and legitimization for, modern episodes of conquest.
If you read *The Journal of World History* and other publications that seek to correct this bias, you'll notice that professional historians in the West are still at the earliest stages. See especially Julia Adney Thomas's recent article "Why Do Only Some Places Have History? Japan, the West, and the Geography of the Past," which documents the institutional bias of the profession towards the West (*Jrnl of Wrld Hist* 28:2 [June 2017]).
To answer address the OP's question directly, I'd offer that the Greece and Rome are not overrated as much as the rest of the world is dismissed and cloaked in our own ignorance. Mesoamerica, West Africa, India, and China, and other places, all have impressive imperial pasts.
But, more to the point, empire, while favored by historians because of their production of documents, is not the only or necessarily best form of human organization. Foraging and pastoral societies existed in large parts of the world, really until the era of nineteenth century imperialism. They are not pre-imperial, but rather have figured prominently in the trade and politics of imperial societies since the "advent of history" with the first river valley civilizations.
Greece and Rome are very important. So are indigenous societies that often marked the extent of empire, the pastorialists who carried goods and ideas and provoded mercenaries and pirates, small island communities that peopled vast oceans, and etc., etc., etc.
Considering that humans have lived on this planet for probably well over 300,000 years and that historians focus almost exclusively on 5000 years of empires, it's safe to say that blindspots dominate our field of visions. Don't dismiss what we see of Greece and Rome because of it, work to broaden your focus. | 14 | 30 |
ELI5: What is the fourth dimension? | We have gotten several answers like space and time. So how can it be both? Can someone explain this to me? | Dimensions are simply a way of specifying where things are. The number of dimensions we exist in can be figured out easily by asking yourself how many different pieces of information are required to determine your location. Four dimensions means we need four specific pieces of information - latitude, longitude, height, and time.
For example, let's say you live in an apartment building and you're throwing a party. If you wanted to tell people how to get to the party, you'd have to tell them the two streets that your building is at the corner of (first and second dimension of space), the floor your building is on (third dimension of space), and the TIME your party is happening at (fourth dimension).
| 14 | 22 |
ELI5: Why is the word "used" pronounced differently with different meanings? Ex: I used the bathroom (yoozed) VS I used to go there (yoost). | Google doesn't seem to turn up anything. It boggles the mind. | It's not because the meanings are different, it's because of the word that follows them. When "used" is followed by "to", it's easier to make a "t" sound at the end of "used".
This is just us being lazy. | 35 | 30 |
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