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[DnD] Do the "good guy" races (elves, dwarves, hobbitses, etc) allow genocide against the "bad guy" races (goblins, orcs, etc) or is it a tribe-by-tribe question? | I can see it going either way. Might be that, say, Blood Hook goblins are "just another tribe, yawn" and yeah they tend to be excitable, but whatevs. Their chieftan can bail them all out of lockup and take them home in the morning. Oh, but those Red Falcon goblins, we hates em!
Or is it more like "Nits make lice. Kill 'em all, Torm will recognize his own"?
| It truly depends on the specific individuals. Certain factions are perfectly happy genociding the shit out of orcs and goblins. Others think that awful. Usually elves tend to be less genocidal whereas humans are more militaristic | 16 | 25 |
Are there any buildings large enough to be affected by the curvature of the earth? How large would a building of this size be? Also, what engineering methods are used to counteract this? | It has a small impact on very long individual structures like suspension bridge spans. Compared to a flat surface the tips of two towers are approximately hL/R further apart where h is the height of the towers, L is their horizontal separation and R is the radius of the Earth (6370 km).
Plugging in numbers:
* Golden Gate Bridge: 1280m main span, 227 m height -> 4.7 cm
* Akashi Kaikyō Bridge: 1991 m main span (world record), 283 m height -> 8.8 cm
As suspension bridges are flexible anyway this is not a big effect. | 29 | 17 |
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Why is String Theory considered to be "un-testable"? | To test quantum gravity theories, you need a situation in which both quantum and gravitational effects are significant. We only know of two such scenarios: black holes and the big bang. All the black holes are too far away and too big to yield useful information about quantum gravitational effects. We can only see back to about 400,000 years after the big bang, so any of the initial quantum gravitational effects are currently unaccessible, although there may be clues in the cosmic microwave background soectrum, as well as any primordial neutrinos or gravitational waves if we are able to detect them.
There is the other issue that string theory is not yet complete to the point where it can make unique predictions, but that can be said about any quantum gravity theory. | 25 | 25 |
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ELI5: How are people able to understand a language but not speak it? What happens in the brain? | I was just with a friend and he talks English to his mum, but she speaks Polish to him. He understands everything, but can barely string a sentence together in Polish. (It's also not a pronunciation thing, he's good on that front).
Surely after listening to a language for years, you should be able to speak it yourself? Especially as you have the vocabulary seeing as you understand everything. | Imagine you have all the words of a language (and their meaning) written on paper, sorted in front of you alphabetically - Im russian, so lets say its russian words. First stack has all russian words that begin with "A", second stack all words that begin with "Б" (russian B), etc.
Now lets say someone tells you the russian word "магазин". You know it starts on M, so your brain checks the M stack until it finds the word, and translates it to "Shop".
But imagine you are shown a picture of a dog, and asked to translate it to russian. You still have all these sorted stacks in front of you, but that doesn't help you in any way. You could translate a word if it was given to you, but you can't just "find" the word you need to speak it.
Also, when you're "understanding" the language, you're usually understanding the meaning, not the word-to-word translation. So if someone tells you "XXXXXX CLEAN ROOM XXX XXXXX NOW XXXXXX ANGRY", you can figure out that they want you to clean up your room asap. But when you try to say it yourself, you can;'t just "make up" the words or grammatic structures that you don't know, and thus you struggle to speak in that language.
This is obviously a gross oversimplification, but if gives you the right idea. Its much easier to recall a word to translate it than to remember what the word is for what you're trying to say - so if you dont use a language actively, you will struggle. | 1,929 | 2,256 |
I just don't get NoSQL databases | Perhaps it's just because of my years of working with relational databases, but for the life of me I can't figure out how a non-relational database works. I've read a number of tutorials and whatnot, and I understand that they are supposed to be faster and more suited for certain use-cases, but I can't really see how.
The Amazon Dynamo DB tutorial, for example, is a movie database. If I wanted to store a cast list for a movie, I see no other way than an array of strings for each cast member. But then if I wanted all the movies an actor was in, I'd have to either do what I suspect is some very slow iteration through all the movies' actors, or store that information in the actor table. But now my data is doubled up and I can't see how that wouldn't create problems.
You might point out that I've tried to use a non-relational database to store a relation, but I can't imagine a database where some sort of relation isn't necessary. Take Amazon, for example. There's a million relationships they must be tracking--purchase to user, review to purchase, item to manufacturer, whatever.
Any insight would be appreciated! | document based databases are really much faster at looking up individual records than relational databases. so, the primary use cases are things like caches (you're just storing blobs of data by a hash) and if your db ever gets large enough to where you're having trouble scaling your server(s) up (these no-sql dbs tend to be much better at scaling horizontally because they're not designed to store relations between multiple types of data).
the second case is what kind of triggered the craze. facebook switched to using a document based no-sql database to load friends data, if i remember correctly. the data is relational, but they traded duplication of data for lookup speed. they really just needed a key subset of user data in order to populate your friends list, but using a traditional relational database, joining on their 2 billion row user table wasn't very practical. so, they basically store a document for your profile or whatever with the relevant user data duplicated in it. they can shard that data however they want into multiple db instances and just route your request to the correct one and essentially get instant lookups of the data they need to display your profile to you.
however, most dbs will never get to the point where you need to do this type of thing. tons of people switched to using something like mongo because they thought it was the thing to do and ended up biting themselves in the ass because they were still trying to use it like a relational database. they would've probably saved themselves a lot of trouble if they just spun up a postgresql instance or whatever that would easily handle the load and amount of data they had.
edit: there are also things like Hadoop (big table databases) which are designed to just accept as many writes of data as possible. rebuilding indexes and such can be problematic to performance if you're trying to write billions of rows of data per minute. querying these tend to be a bit slower though, so most of the time you'll just write operations to aggregate data sufficiently enough to where you can shove it into a more standard relational database to actually work with the data. | 34 | 45 |
ELI5: Why do electronics break when they get wet? | Electronics are very sensitive to the amount of electricity that each component receives.
When electronics get wet, the water conducts the electricity all over the place and zaps the components with voltages they are not designed to handle. Connections melt or burn.
Basically, it's like what happens when a ocean wave crashes in on top of a sand castle. It obliterates the subtle design needed to make it function. | 37 | 42 |
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Are the ideas of individuality and separatism taught to us, or are we born with the truth of that we are separate beings? | I hope I worded this correctly.
I’ve been thinking on the truths and mechanisms we are born with universally, opposed to which are taught to us socially.
I assume that some truths are instinctually apart of us, regardless of social learning. Such as momentary fear as a response towards self preservation, the drive to self preserve and to avoid pain, the sexual urges to reproduction, and our recognition of water for drinking.
However, I feel that individuality is greatly taught via words. If we had no words to identify ourselves as individuals, how would our lives be? Would we see each other as separate beings, or as a functioning part of a greater being or organism?
I ask this question because I believe that separatism causes a lot of problems in our lives and society. We see a lot of religions and spiritual practice gravitate towards human “connection” and reform with the universal harmony of nature and all beings. We know that separatism and individuality is a foundation for comparison; and therefor discrimination.
This also challenges the ideas of persona and ego. If we did not have a learned “self”, would we be driven by ego and presented with persona?
Without a learned truth of “self”, would we have a need for a linear time perception if the ideas of birth and death were irrelevant? | I'd say the current prevailing thought in infant development is that we don't start out with an understanding of ourselves as separate beings, but that it's something we necessarily learn over the first year of life as we learn to distinguish between the parts of our experience that are directly responsive to our thoughts (e.g., body movement, voice) and the parts that are not not (e.g., other people).
The values of communalism vs. individualism represent a different question, though. That does seem to be taught as evidenced by culture-to-culture variation in the phenomenon. | 28 | 38 |
[Star Wars] Were there massive intelligence differences between the sapient races in Star Wars? | Is there some natural cap on intelligence in the Star Wars universe preventing some aliens [droids excluded] from being super geniuses that can think circles around others? Do the super-intelligent ones just stay in academia and avoid politics and that's why we don't see them? Are all of the aliens *really* in the same, narrow intelligence band, or are there really huge differences in intelligence that simply never come up? I'd *assume* humans must be near the top if there is one, just judging by their dominance in politics and well, everywhere. But I never really get the feeling that there are some species that just can't compete intellectually, in the same sense that a child can't against an adult. | Certain species do have a higher capable intelligence than others. This is usually offset by physical limitations or artificial enhancements. In limited fashion many aliens like the Duros will find gainful employment as data analysts and such but usually xenophobia and other issues keep them from expanding further. A lot of naturally gifted races can be matched or even surpassed by droid brains or cyborg enhancements making it a moot issue in developed areas of the galaxy. And on the opposite side theres aliens with extremely low intelligence that still flourish in the galaxy. Being intelligent or unintelligent doesn't matter too much in star wars. Machines can match natural intelligence and physical abilities can make up for a lack of it. Humans are considered to be average with races like the duros and bothans at the more intelligent end and species like Gamorans and Geonosians at the lower end. In general it's safe to remember a computer can outthink you and a blaster bolt doesn't care how smart you are. | 17 | 15 |
[RPGS] Why do I keep finding fragments of journals spread all around instead of one place? | I can never find them in just one place or book? Why would someone tear out pages or type entries in different computers around the wasteland? | Possibilities include:
1) There are many copies of the one journal, all of which were almost completely destroyed except for a page or two. The same thing might be said of trying to recreate some old form of boat or machine, and there are very few of the parts still around. Only the diligent will assemble a fully restored stock version.
2) The journal was written by someone with "Johnny Appleseed Kinetic Assembly Sickness" (JAKAS Disease) who wants to 'seed' his manifesto about the world. Instead of copying it, he puts a page here and there.
3) Its a holy relic, and pieces of the 'One True Journal' were take by the faithful to places of worship scattered about the world. Generations later, the worship has faded away, but the relics remain.
4) Ooooh, shiny! Some animals found the pages of the journal useful for something, like nesting material. Indestructible nesting material. Now, hundreds of years later, the nesting material has been used countless times but it scattered everywhere.
5) It was a collectible. Not holy, but cherished for some other reason, like "the mad writings of that famous screwball wizard" or 'forget the words, the illustrations on the other side of the page are amazing art" or something. As such, collectors put them in their deepest safespots. Now, generations after those collectors have died off, only the vaults (and vault keepers) are left.
and so on
Or for the boring reason, its a scavanger hunt to test for a worthy hero, blah blah blah. | 49 | 82 |
[D&D/GeneralFantasy] Can adventurers "breathe" a tamed Air Elemental? | If yes, bonus questions:
* How long would it take a human adventurer to consume all of the oxygen contained in a large-sized Air Elemental?
* Would doing this be fatal or injurious to said Elemental?
* Could this method be used for deep-sea and/or space travel? Can the Elemental hold itself together in these extremes, or would it compress or dissipate?
* Rather than such extreme travel arrangements, could you store an Air Elemental in a Bag of Holding, allowing you to transport living things without them suffocating?
Thank you in advance for all of your outside-the-box-of-holding thinking! =) | depends on the lore, but I've allowed it in shadowrun for example, where our creative summoner filled a room with water via a water elemental, sealed us hermetically in rock via earth elemental and filled the chamber with air via an air elemental. He then used another air elemental to zap the water outside and kill everyone in the room.
He's not allowed to play summoners anymore. | 30 | 59 |
How does salt (NaCl) accentuate flavors in foods? | This has come to my attention after consuming unsalted peanut butter for the first time. It felt like the flavor was dulled down. I wondered how NaCl changes the taste so drastically.
So I googled around...
..and I found the following on [The Straight Dope](http://www.straightdope.com/columns/read/2718/is-sea-salt-better-for-you-than-regular-salt):
"adding NaCl to some foods can increase the volatility of certain chemical compounds, meaning the molecules are more easily released to the air, and of course aroma is an important part of the taste experience. Finally, studies have shown the sodium in salt can suppress bitter tastes."
What I don't understand:
1. How does it "increase the volatility of certain chemical compounds"?
2. How does this apply to foods, say vegetables, which may not have a really distinct "aroma"? (i.e. steamed cabbage or carrots have a much more lively taste after a dash of salt on it)
Are there any food scientists/chemists that can explain this to me please?
| I just took a Vertebrate Sensory Systems course, and the reason that salt enhances taste is this:
Each taste in the mouth uses different mechanisms to signal that particular taste, most of which involve the opening of sodium channels that cause signaling to the brain. Since salt itself (NaCl) increases the amount of sodium outside of the taste receptor cell, the gradient is stronger, and thus more sodium enters open sodium channels, causing more signaling for any particular taste. | 76 | 132 |
ELI5:Why do I see articles daily practically saying we have found a cure for things like cancer, yet no cure actually exists? | Scientist here.
We haven't cured cancer, but we have cured MODELS of cancer.
Scientists will often use MODELS of cancer, because there are so many types of cancer. For example, we will take a biopsy of a live person's breast cancer tumor, throw it in a dish, and do crazy stuff with it to make that cancer able to live forever in said dish.
This is now a "cancer line". For example, a cancer line of triple negative breast cancer. Specific cancer to find a specific cure.
Nowadays how this starts is we analyse this "cancer line". We look at all of its DNA to find that it lacks "gene x" or "protein y" compared to normal healthy cells. We find a target that is very different (or totally absent) in the cancer, and a target that we like, and think, "hey, if we fix that one thing, can we fix the cancer?"
So we find a drug or a genetic treatment and target it to fix this problem.
Many times, this "gene x" or "protein y" that is wrong in the cancer cell is so important, that fixing that one little thing out of 100,000 other things can save the cancer.
So anyways, we take this cancer line, and take an inbred mouse family with a real shitty immune system. We inject the human cancer cell line into this mouse and make sure the mouse's shitty immune system is too weak to fight off the cancer. If the mouse can 'get' the human cancer, and the cancer spreads and kills the mouse, success!
Then we give the mouse this simple treatment to restore 'normal' function to our target gene or protein. And lo and behold, the mouse is cured of all cancer!
This is a lousy way of curing human cancers, which are all unique and merely follow trends, however it gives us more insight into these trends, as well as understanding of how exactly the cancer is spreading and killing people.
It also cements our classifications of cancers. When we find 'treatment X works in this model of brain cancer but not that one', then we can know in real life those patients need to be treated differently.
tl;dr scientists do it with models | 1,369 | 1,814 |
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ELI5: Why do multi-lingual people seemingly, with no reason, switch between languages while talking to someone who is also multi-lingual? What benefit does it have over staying with the language they started the conversation with? | It's called code-switching, and it allows the speakers to draw from both languages' vocabularies to express ideas. Some words in one language don't have nice, short, or eloquent equivalents in another, so if you're speaking to someone who knows both languages, you use whichever one helps you to most easily get your ideas across. | 56 | 15 |
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What determines whether or not a substance has a strong scent? | For example, why does an ester have such a strong smell? | In short, there are 2 main factors:
1. Volatility of the substance. In order to be detected by your olfactory system, molecules of the compound must reach your nasal cavity, and that generally means they need to be either gaseous or suspended in the air or captured in the moisture in the air. Esters smell strongly because they are volatile compounds (they have weak intermolecular forces) so they reach your nose easily.
2. Sensitivity of your nose. Your olfactory system has evolved to detect certain molecules very well, others less well, and still others not at all. The more sensitive your nose is to a substance, the less is required to get a response. | 23 | 16 |
ELI5: what does it mean to overclock a CPU? | what does it mean to overclock a CPU and what are the pro's and con's? | Overclocking means making your CPU to work faster by increasing the default clockrate (GHz). Increasing the clockrate makes the CPU less stable (might crash without reason) and more hot (requires better cooling).
If you find the sweet-spot (stable, not too hot, maximum GHz) you're gaining tens of percents of performance increase for free.
It's a lot easier than you think. Basic overclocking is basically just typing a higher number in the CPU settings (BIOS).
I would compare it to tuning your car engine to make it faster. When you're going faster, you need better brakes and stuff. If you make your Fiat Punto go 500km/h, it will became unstable without modifications. | 24 | 20 |
If cancer and psoriasis are both overactive cell growth, what is it that makes them different? | If you were to compare skin cancer vs. psoriasis they are both described as overactive cell growth, though with different results and degrees of danger. A) how are they different, and B) what is it that makes cancer more dangerous than psoriasis? | oncology doc - Interesting question!
The short answer is that you're right, psoriasis and cancer are both due to overgrowth of cells - but different kinds of cells, and for very different reasons.
Try to visualize this a pyramid. At the apex is a single cell type. On the next level, there are two cells. Then 4 cells on the level below that. That's sort of how cellular differentiation works in the body; a non-specific cell gives rise to slightly more differentiated cells, which gives rise to slightly more differentiated cells, etc, until you have mature cells of X,Y,or Z function.
There are a multitude of different kinds of cancer, all of which are due to an uncontrolled proliferation of a certain cell type. Leukemia, for instance, is due to clonal overgrowth/expansion of an immature blood cell precursor. Something like, say, breast cancer, is due to an uncontrolled overgrowth of the cells that comprise certain types of breast tissue. Cancer cells have typically undergone/acquired some mutation that allows them to either proliferate without the need for external stimulus, or ignore external stimuli telling them to stop dividing, or shuts off a cellular 'self-destruct' mechanism that should make them stop once DNA damage occurs.
In psoriasis, there is an overgrowth of a well differentiated type of cell - the keratinocyte. HOWEVER, and this is the key, the overgrowth is not due to a driver mutation as in cancer, but rather, the result of an inflammatory stimulus. In psoriasis, there is hyper activation of the pro-inflammatory/immune cells within the skin. That activation causes them to release cellular signals (cytokines) that encourage the keratinocytes to proliferate and divide far faster than they usually would, because those signals are meant to be released when local destruction occurs and extra cells are needed to fill in the damage. That proliferation isn't due to some mutation in the keratinocyte, but rather, overactivation of immune cells, which are telling them to do so. To take it a step further, the keratinocytes are then attacked by the immune system, release signals that cause the recruitment of immune cells (because there is localized inflammation), which continues the process.
TL;DR: Cancer is an uncontrolled proliferation of cells. Psoriasis is an immune deregulation where inflammatory cytokines are causing local inflammation, which causes cells to proliferate secondarily.
I hope that helps! | 38 | 19 |
ELI5: what does it mean to “sing from the diaphragm”? And is there a physical sensation that tells you you’re doing it properly? | When you breathe, you expand your lungs either by moving your shoulders up and chest out, or by expanding downward into your abdomen which allows for a bigger breath. When you breathe and your belly expands, that’s breathing with your diaphragm. The diaphragm is a sheet of muscle just under your lungs at the top of your belly which pulls open the lung cavity helping it expand fully and then can be used to push the air out in a controlled manner. As you sing, your belly should slowly go back in as the diaphragm pushes the air through your voice box. Then breathe in again through a relaxed mouth and throat and your belly should expand out again (no shoulder movement) That’s how you know!
If you are still having trouble, try laying on the ground flat on your back with a hand on your belly and then take a deep breath. Watch your belly and hand rise. Pay attention to how that felt and see if you can do it standing up.
Happy singing! | 18 | 19 |
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CMV: The college 4.0 GPA scale is dysfunctional and poorly represents students. | Been wanting to do one of these for a while now.
​
I find that the 4.0 scale leaves a lot of the students' academic work on the cutting room floor and presents them in a weird manner.
A student can have a consistent score of 89%, which equates to a B+, thus a 3.3 GPA.
*But* a student can have a consistent score of 90%, which equates to a A-, thus a 3.7 GPA.
1% ( to \~5%) of a score in-class has the weight of about 10% on a 4.0 scale.
And conversely, 88% has the same GPA value as a 89%.
90%= 3.7
1+/-
89%= 3.3
1+/-
88%= 3.3
This quantification is inconsistent, a student can increase their score by 1% and receive either a 0, 0.3, or 0.4 increase but decrease their score by 1% and receive a potentially different value change.
A subject that worsens this metric is when students request their professor to round up their grade (typically 89 to 90), as not everyone can benefit from a 1% boost no less have a professor who is willing to do so.
I simply think its inappropriate for a student to not be properly represented by the percentage they earned in-class. Students with a 3.7 aren't that different from those with a 3.3, but yet the scale appears to magnify their difference. | I would argue that a mitigating factor is that GPA isn't really used for individual classes, but over the whole education. In that time frame, we might assume that a student's course grades will be randomly distributed about their "true competence" in that class, so in fact an 89% student is only slightly less likely to get an A- than a 90% student. Thus, their average grade should tend to reflect that, where they'll both be hanging out around a 3.5 over the forty or so courses that constitute a degree. | 22 | 95 |
Why use an interface as a type? | ​
Working on Amazon AWS S3 with the AWS SDK.
The official AWS docs show an example of creating a Client like this:
`IAmazonS3 Client = new AmazonS3Client(...`
Why are they using an interface as a type reference? I changed it to this, and it works exactly the same:
`AmazonS3Client Client = new AmazonS3Client(...`
This isn't strictly an AWS question. It's just a general OOP question (unless Amazon does this for some specific AWS reason). | To support other classes that inherit from the interface of course
For example, you could have an EmailSender class and an SMSSender class, and you can instantiate either, but it’s much easier and more flexible to have an INotifier class that both inherit from and use the Notify method in it without caring for the details of the actual class
It prevents you from building class-specific details into higher levels of your application and allows you to quickly and easily change logic. Any IDE will require you to create a Notify method from any class that inherits from the INotifier interface so its a guarantee that the method *will* exist in higher levels of your app | 13 | 18 |
Is visible light, or any other form of light for that matter, affected by wind? | Say I point a laser at a wall. If I turn a fan to face *perpendicular* toward the beam, would it push the light across on even an atomic scale?
EDIT: Changed parallel to perpendicular | Wind is accompanied by variations in air pressure and that variability induces variations in the refractive index of the air. Those variations will result in slight wobbles in the direction of light. It is for this reason that stars twinkle. | 24 | 19 |
ELI5: How do rivers flow continuously? | I understand the water cycle in that water is evaporated, condenses, and precipitates which puts water back into the ecosystem, but how does a river continuously flow millions of gallons of water when it eventually empties into an ocean? Where does all the water come from to keep it going nonstop? | The water in a river comes from many different sources. Let's try to think of a few. There are springs, where the water bubbles out of the ground. There is rain, where the water precipitates, or falls from the sky. There is the melting of glaciers or snow cover. The water also seeps out of wet ground, and the water we pump out of the ground for use in our homes and businesses probably gets treated and then put back into the ecosystem, where it flows into rivers.
The watershed, or area in which the water will flow to a particular body of water, is quite large for most rivers. All of these sources combine over that large area, to form the river. Rivers naturally rise and fall over time, as the amount of water flowing in changes with seasons and weather. | 13 | 16 |
ELI5: Why can't we breed with other species? | Why cant we breed with species like gorillas, when close species, like tigers and lions or horses and mules, can? | The general rule of thumb for interspecies breeding is that it comes down to chromosomes, which are strands of DNA. The rest of the Great Apes (Gorillas, Chimps, Bonobos, Orangutans) have 48 chromosomes, but 2 of these chromosome have fused in Humans, leaving us with 46 chromosomes. The greater the difference in the number of chromosomes, the harder it is for species to breed. Basically, the sex cells (sperm/egg) have problems aligning and combining when the chromosome count is off.
This hasn't stopped animals with different number of chromosomes from interbreeding. Mules are the best example. Horses have 64 chromosome and donkeys have 62, so this is similar to the difference between Humans and the rest of the apes. So we can see that a different number of chromosomes is a problem, but not an impossible barrier, for making hybrids.
The other main biological problem comes down to the immune system. Your body automatically recognizes when things are "not-self." Any outside matter that enters into your system is immediately attacked by your immune system. For pregnancy, this concept is most important when it comes down to blood types. The "positive/negative" you hear about human blood types refers to a specific blood type. Basically, if a mother is "negative" and the fetus is "positive" than the mother's immune system will attack the blood of the fetus, which can lead to a miscarriage. Chimps and humans have equivalent systems that they share. So, a humanzee fetus would need to have a mother and father with matching blood subtypes.
The biggest problem to breeding humans with other apes is not biological. The simple fact is that, while it is biologically possible (if not likely), making a human-ape hybrid is a bit too mad science-y for most people. No reputable institution would fund the research, no ape center would allow their animals to take part, and the outcry from the public and scientific community would shut down any private project pretty quickly.
| 40 | 46 |
CMV: Passing Another Gun Control Bill Will Make People 'Feel Better' Until the Next School Shooting, But That's About It. | This is not an in-you're-face political post, so please don't bother replying with political or emotional diatribe.
Here's my stance: There has not been a time in this county's history where you couldn't get your hands on a gun. Picture 1950's suburban America: Dad buys Timmy a .22 rifle for his tenth birthday, while the Boy Scouts of America are doing their darnedest to arm every other young man and to teach them how to shoot proficiently.
Since that time, many federal (and ever more state) gun control laws have been passed in order to limit access to guns.
Here's a (very) brief list:
1968: Gun Control Act of 1968. 1972: ATF starts requiring firearm licensee qualification to purchase a firearm. 1986: The Armed Career Criminal Act. 1990: The Crime Control Act of 1990. 1994: The Brady Law & Assault Weapon Ban. 1998: Required National Instant Criminal Background Check to purchase a firearm. 2008: The National Instant Criminal Background Check Improvement Act.
So, in 1950, American Timmy has less legislative hurdles to jump over in order to get his hands on a gun than today's Timmy does. Yet, 1950 Timmy didn't internally de-humanize his fellow classmates and decide to end their lives with a gun.
The guns have always been around. There has been increased gun legislation over time. Yet, school shootings continue or worsen.
What has changed here? What is the core problem that has developed (that 1950's Timmy didn't have)? And, why would more gun legislation solve that problem?
My general theory here is that you could pass a gun control bill tomorrow that would literally end the sale of firearms in this country, and the school shootings would continue.
_____
> *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!* | Solving the underlying issues would be great, but if you regulate guns to the point that in 20 years a kid will be unlikely to have learned how to fire one, and having access to a gun would be the exception rather than the norm and a major red flag for anyone with any behavioral issues, the frustrated / enraged / mentally ill kids of that time would have to find another outlet - which probably won't be nice either, but at least it will be much less likely that it's a machine designed to efficiently kill people from a distance... | 12 | 34 |
(Politics) How much do you need to know to be considered “enough knowledge” in regards to where deciding what your position is? | another way to look at this question is to consider that you may have multiple competing positions which have different levels of justification. in other words, what you consider to be "true" of the world, politically, should be a function of what you know, what you don't know, what you've considered, and what you haven't. since what you call your knowledge is limited, and since it's probably true that some of the things you "know" may not be sufficiently justified or even ultimately true, your certainty that some political position is worth taking should be less than total (perhaps much less). you should also feel fairly confident that the future will produce new ways of understanding humankind, civilization, and political orders that have different or more explanatory power, and may map better or more completely onto reality - but you can't have them as positions now, because they don't yet exist.
this is all to say that political positions should be hedged with acknowledgement of the incompleteness of your own understanding and the underdevelopment of concepts through which to understand politics. it's fine and perhaps practically necessary to take a position, but really digging your heels in the dirt is probably unjustifiable. | 41 | 82 |
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ELI5: How is it possible that athletic results keep getting better and better; will they ever plateau? | It seems like every Olympics, World Championship, etc, at least one record is broken, usually more. It's to the point now where gold-medal-winning 100m sprinters of a few decades ago would barely even rank in the top 10 today.
I know some of this is down to better training and nutrition, better equipment (more so in some sports than others), but surely there must be some limit that results from the human body? Will we ever hit a point where we have seen basically the fastest a person can run, the most weight they can lift, the furthest they can throw a javelin, etc? Where the records then just stand indefinitely?
**EDIT:** Thanks everyone, for the insightful responses (and areas to look at further)! Much appreciated and does help it make more sense to me. | Theoretically, the human body has finite limits that it cannot exceed. Bones can take only so much force without breaking, the human circulatory system has limits due to size, etc... However, there can always be outliers that are genetically better suited than the average human for certain sports. So in other words, we could plateau, but someone better could always be born to break the record. | 55 | 70 |
Trying to understand which universities are the best in a specific field | In my case, I am interested in nutrition/dietetics. The problem is that most of the official rankings ( shangai rankings, top universities ) do not have a ranking in specific for nutrition. There is agriculture but I dont’t know if nutrition is included in it, or food science/food technology.
How do I evaluate the quality of the university in this specific field? The only one I know by reputation in the Karolinska instituet
I am EU based btw so I was considering eu universities.
Also, I think I have two main interests, which are sport nutrition and nutrigenomics. I know that there is some nutrigenomics applied to sport research. Should I try to find professors who do research in this field and go there, even if the University itself is not renown that much?
EDIT: talking about master level studies | For what level of study? PhD level with intent to be a researcher - you should be making your decisions based on how specific your understanding of what you’d like to study is. If your interests are broad, you are probably better off finding a department with a diverse faculty mix. If you’re certain that you will only study the intersection of sport and nutrigenomics, you need to find an academic whose speciality that is. The department prestige matters much less in this case. You might also consider a department that is strong in one area or another, with multiple professors in that area of study. Sometimes it is not possible to work with a certain professor so you might need to be flexible in your choice of advisor and having several options is good.
If your goal is to be a sports dietitian, then you should be looking at the quality of the academic programs and the rigor they offer. Prestige might factor into this. | 25 | 41 |
Could someone step me through the math/deduction/reasoning that Einstein did to come to the conclusion that bodies of mass and energy distort space-time, hence macroscopically observed as gravity? | Large or small, Responses all! | You need three assumptions:
The laws of physics are the same for all inertial observers.
The speed of light is the same observers.
An observer in freefall is in an inertial frame.
A corollary of the third is that acceleration is indistinguishable from a gravitational field. Imagine being in an elevator in outer space, and suddenly you feel attracted to the floor. You can't tell if the elevator is accelerating one way, or if gravity is pulling you the other way. Now, imagine that there's a hole in the side of the elevator, and someone fires a laser through it. If the elevator is accelerating, the laser will follow a curved path (it's dusty inside, so you can see it). But because acceleration is indistinguishable from gravity, it could also be a gravitational field that is causing the laser beam to curve. But if the speed of light is the same for all observers, it means the path that light takes must be the shortest path, or else you could follow a Euclidean line and get there faster than light. This means that in order to be consistent with these assumptions, the presence of a gravitational field made it so that the shortest path through spacetime, the one that light takes, is curved. | 61 | 30 |
[R1/Star Wars/ESB] What purpose do these big ass glass screens with huge over lapping circles and lines on them serve? | It's a way of representing 3D space on a 2D surface.
For example, you put your planet at the center of the glass. You then draw concentric circles around your planet to show distance. The closer the ship is, the closer it moves on the circles.
*But* this only shows you the distance of the ship, not the approaching vector. So you know the ship is 10,000 kilometres away, but is it heading towards the North Pole, the South Pole or the Equator?
So you draw a line to show the Z axis in oder to get the exact co-ordinates of the ship. If the line comes from the top, it's heading towards the North Pole, if it's heading left to right it's coming from the West, etc. | 30 | 31 |
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CMV: Reviews of restaurants by food critics are basically useless and the profession of "food critic" is similarly superfluous. | A review of a restaurant is an opinion given by someone who is basically paid to give their opinion (cue the sound of half of reddit creaming their drawers). That opinion is informed by a single visit to a restaurant with little to no knowledge of how the restaurant works.
Reviews are one snapshot of often one or two dishes eaten one time by one person that can have a huge impact on the success or failure of a restaurant. That's a lot of power to give to something that ultimately says nothing at all about the restaurant.
The enjoyability of food is nothing if not subjective; while there is science to suggest that certain things may be more agreeable to the human palette (the old axiom of "if it tastes bad, smother it in bacon and/or cheese") than others on the whole likes and dislikes are individual. A reviewer might find something they dislike however that same dish might be quite popular or liked by many others.
You're essentially giving one person's opinion much more weight than it deserves. The argument is that a critic knows something about food or has experience with other restaurants and can compare what they experience to what they know and come up with a better opinion.
That still doesn't change the fact that you have one person giving their opinion of what they think is good and bad regarding a restaurant and it still stacks up to be generally useless. You have a slightly better informed someone giving their subjective view on a restaurant, and we know how well informed [random strangers](http://cdn.iwastesomuchtime.com/June-30-2012-17-51-06-f0107627edf7b5bd3a085cc32084a6e4width600x.jpeg) can be with regards to reviews.
Shave off that part of the job and a "food critic" basically becomes someone who tells you that there's no roaches or severed fingers in the food (which, as we've established, reflects one experience with a restaurant). This, to me, calls into question why being a "food critic" is even a thing, much less a thing with as much power as some critics wield.
Add to all that you get food critics desperately trying to justify their existence by engaging in [snobbery](http://articles.chicagotribune.com/2011-08-03/entertainment/ct-dining-0804-hot-dog-20110803_1_hot-dog-ketchup-vienna-beef) and general tribalism with regards to what people put on their food or where they get it from and the entire profession seems like a needless dead weight on the culinary world.
So, CMV.
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> *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!* | 1. If you're into food, you read a bunch of food critics and try out the restaurants they recommend, over time you start to know which critics share similar tastes to you, and you start to trust their recommendations more.
2. Reviews of restaurants serve as an interesting way of discovering they exist. Reading someones opinion of a new place is much more interesting than reading a list of facts about it. Even if you don't put much weight on that opinion.
3. Well written reviews of anything can be entertaining in their own right, especially bad reviews, they can be really fun to read.
4. If a review says something is amazing, it's probably not shit, it may not be to your taste (if you read a review of an amazing new seafood place, and hate seafood, you can work it out), but it's unlikely to be awful.
5. Yes they don't try everything, and quality may vary from night to night. What one good meal really says is that the person running the show knows what they are doing, this bodes well for other dishes and other nights. | 12 | 22 |
ELI5: I often hear that "in western society, breasts are sexualized but in other places [I commonly hear Africa], they are not sexualized and therefore not as big a deal." So why is it different in western society, why did they become sexualized? | I am aware it has to do with media but what happened that the media decided to make breasts sexualized objects? | The Abrahamic religions stress modesty in women. These religions were central to the rise and formation of Western culture. So even though religion is becoming less important in the West, the old cultural standards are still in effect. | 66 | 107 |
Eli5: How does Aloe Vera assist in reducing the symptoms and help heal sunburns? | There are a lot of different things that happen in your skin when you apply aloe vera. It stimulates collagen production, helps bind moisture to the skin, it's an anti inflammatory, and it's even an antiseptic.
In the case of sunburn, this all helps your body's immune response to be more effective, while protecting the skin from more irritation. | 25 | 23 |
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Why do we have to avoid bacteria from our shit and snot once it's outside our body, but it doesn't make us sick when it's inside our body? | Certain bacteria don't do much harm when they're living where they're supposed to live, but if they go somewhere they're not supposed to be, they can cause trouble. The bacteria that live in your gut are just fine there, but if they get into your eyes or mouth, they can make you sick.
There's also a lot of bacteria on your skin, all the time. They can't get into your body because they can't get through your skin. But if you get a cut, they can get inside and cause a ruckus. These are called opportunistic infections -- they're caused by organisms that normally don't do anything wrong, but if given the right opportunity (weakened immune system, injury, scrapes, etc), they can make you sick.
Think of it like this: If you have a cat who's normally lives outside and doesn't come in the house much, what happens when you bring him inside for a night? He freaks out and shreds the curtains! It's kinda like that. :)
**Edit**: In case you're not 5, the ELI-12 version continues: E. coli is a good example. It lives in our gut and doesn't get in trouble. But if it gets in your mouth, it can make you sick. ~~Whenever you hear about an E. Coli outbreak at a restaurant or from vegetables, that's usually because someone who handled the food (be it while picking it in the fields or while preparing it at a restaurant) didn't wash their hands after going to the bathroom. The bacteria that were in their colon are now in your mouth.~~ see /u/RuPaulRudd's correction | 182 | 456 |
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Took a few years off to travel and take a break, how would you portray that on your resume(US)? | I've been coding professionally for \~25 years and was stack before. A bunch has changed in my short break, but I did keep somewhat up to date. Personal projects where I did poc's with ang/react/vue, along with .net core. Debating how to describe it all.
Dealt with many new hires/resumes over the years, but never from 1 that took a real break. Most Americans fme, basically look down on it.
Would you like to see a job post for those missed years? What I did coding wise personally...
Or would you prefer to see a description of what I learned from my travels? Not necessarily code.
Don't get me wrong, I can get someone to vouch for me and completely ignore the break; I'm not a dishonest person tho. That may be my best option for getting an American based job tho. | Use a referral to get a foot in the interview process and be honest. You’ll probably have to “settle” for a job. Then switch in a year since it’s far easier to get hired if you’re already employed. Beat of luck. | 10 | 26 |
[Ben 10] Does Ben have any aliens that can heal other people? | I know Ben has a lot of aliens with regeneration powers (Wildvine, Swampfire, Diamondhead, etc.), but does he have any aliens that could heal other people through their powers? Alien X I guess could, but that's more because that alien is so OP it's easier to count what it *can't* do. So, how many of his aliens, from either OG series or the reboot, could most likely heal people? | Let's see:
Grey matter would probably be able to diagnose medical problems/injuries along with limited manipulation of nerves
He mentioned using ghostfreak to help heal Max(though he was likely just brainstorming and wasn't sure)
He could probably cauterize wounds as heatblast, though that's kind of graphic for a cartoon.
Upgrade could probably heal mechanical beings to some extent
He used swampfire's tendrils to hold highbreeds arm together so it could heal, even left a neat scar
Big chill could probably cool a fever or remove foreign objects via phasing
Brainstorm would have the same intelligence advantage as grey matter, with electricity to use as a defibrillator or electroshock therapy
Sorry, can't remember past alien force. Hope that helps | 16 | 18 |
Why dont more people in the US get illnesses from mosquitoes even though the same mosquito may extract blood from several hosts? | If a mosquito extracts blood from a squirrel, and then gets blood from you, and then gets blood from some other person, and so on, wouldnt their be a prevalence of some kind of disease spreading from host to host? | To spread via mosquitos, pathogens need to be pretty specialized. Mosquitos don't take all that much blood from one host, and transfer far less to the next host, so if the pathogen is just in the blood, it's very unlikely that there will even be a single pathogen particle in the transferred blood.
Vector-borne pathogens, like yellow fever or malaria or dengue, overcome this by replicating in the mosquito and often by entering the mosquito's salivary glands. Mosquitos transfer more saliva than blood, and if the pathogen has replicated there and is present in high concentrations, it's easier to spread.
But look at the challenges this presents to the pathogen. It has to be equally effective at replicating in a mammal and in an insect. In the mammal it has to spread into the blood and be there in high concentrations, and then it has to follow a completely different pattern in the mosquito. The body temperatures, the receptors, the cell types - everything is different, so the pathogen basically has to carry double sets of everything.
So just generic pathogens don't do this. In the US, there are a handful of the specialized pathogens that are arthropod-born. West Nile virus is well known. There are several types of viral encephalitis (Venezuelan Equine Encephalitis, Western EE, Eastern EE). There are some tick-borne diseases like Lyme Disease and Colorado Tick Fever and so on.
Some of the other diseases used to be present in the US, but were eradicated. Malaria was eliminated by the precursor of the CDC in the 1950s. The process reduced the number of the worst types of mosquitos, the ones that spread some of the worst diseases. That's helped as well.
Currently of course there are some mosquito-born diseases that are trying to move back into the US, as climate change makes larger regions more attractive to the mosquitos. Zika was found in Florida. Chikunungya has been found spreading locally in Florida. | 55 | 39 |
CMV: Within the next few centuries, homogenous countries will cease to exist, no matter how hard countries try to prevent this. | As countries begin to prosper and as their quality of life increases, people from all over the world will have more opportunities to work and live within different countries.
There are many people praising some countries for refusing refugees and being much stricter with immigrates. But I for one feel that this is a lost cause. I feel that globalization and multiculturalism will be inevitable once a country prospers.
I will give you a two examples:
The country of Czech Republic. The Czech Republic is arguably one of the most successful former soviet countries to this day. As the years go by, the country has been rapidly improving in many different ways. From its GDP, to Standard of Living, all they way to attitudes toward liberal ideas such as gay marriage.
The country has come a long way and it is showing. Because of this, this country is becoming more and more attractive to people from all over the world.
Statistics have been showing Czech Republic to a net positive population growth with the past few years. This is largely due to immigration.
And yes, a large majority of that immigration is from other European countries. But, it is definitely not unusual to see Non-Europeans within larger cities such as Prague and Brno.
As the Czech Republic becomes more prosperous and international, the country is continuing to attract businesses, expats, and immigrates alike.
The Czech Republic’s has many minority groups and that includes many non-Europeans. For example, their is a Vietnamese minority that is in the thousands, their have been a increasing number of Indian’s applying for work visas, and from what I’ve been told it is not uncommon to see black people (africans and expats alike) studying or working within Czechia.
As of now, Czech Republic’s future looks promising. Because of their success, the Czech Republic will become more multicultural. If they keep moving forward in the same direction, they will become as prosperous as many Western Europe nations. This will inevitably lead to more immigration, similar to western Europe.
Now obviously Central and Eastern Europe have been pretty clear on their stance on immigration and the situation with refugees. And I don’t see that stance changing anytime soon. So before the comments come rolling in, I would like to state that those countries becoming multicultural is not going to because of refugees. It will be a more healthy type of immigration, mainly a brain gain.
Another example that I feel is similar to this would be Kenya.
Kenya as a whole has been prospering greatly within the last few years. There has been a large increase in infrastructure and quality of life has improved a lot in both major cities and small towns/villages.
Kenya as a whole has also started to become Africa’s international hub. This has been leading to a more people immigrating their. Not just other Africans. Many immigrants and expats are starting to make a life there. For example, there are many more Chinese people living in Kenya. There are quite a few expats from Europe and the Americas living and working within Kenya because of the increase in international business is settling there.
There are many more examples of countries prospering and gaining an international community because of this. But this post is already getting a little too long, so I will stick to two.
All in all, I feel that in the future all countries will eventually prosper and grow. Soon enough the whole world will become much more accessible to everyone. People from all around the world will always be interested in other places. Even those who live in countries with the highest quality of life end up moving to other countries. Be it because of work, marriage, or adventure... people will always have a excuse to live somewhere new.
I feel that eventually the world will reach a point where every country is multicultural to at least some extent.
Now I’m not saying that every single country in the world will be similar in demographics to the United States.
I am saying that I don’t think there will be countries that are like 96% X ethnicity.
I feel we will have much more countries that are like 70% main ethnicity and 30% other (with a variety of people from all around the world).
For example, a country like Poland could be like 76% Polish and 24% other. And that’s what will keep each country from losing its main culture. I feel that most countries will still have a majority of their own people.
I’m definitely not saying that we’re all going to be multicultural hell holes with no identity whatsoever.
I feel very few countries will actually end up being majority-minority. So please don’t panic or dismiss my thought.
But remember everything I just said and remember that just my opinion. Feel free to try to change my view :)
And please... no rude comments about being a delusional leftist or some BS like that. I just wanted to let my thoughts out and have a discussion.
Thanks to anybody who read the full thing! Have a great day! | Outside of possibly nationality, that stands true already. Whether it be religion, culture, or race. Every country has a mix of at least one of those factors within it already. You use broad terms like “European” which destroys any separate cultural or racial differences between the people of Europe. Eastern European countries, as you used in your example, are already incredibly far from homogeneous. You have multiple different cultures, religions, racial groups, and nation backgrounds. Rome the father nation for Europe as it stand today wasn’t homogenous. Greeks, Italians, Arabs, Scandinavians, and many others were all apart of that father nation that eventually lead to Europe as we know it today. There are no homogeneous nations, even those that try to be fail. | 27 | 42 |
How do stoplights actually work? | I'm a delivery driver and just today while waiting a few miniutes at one did I actually question the science behind it. My question is what sensor is used to get a signal and what logic is behind the programming when it gets a signal? | To detect the presence of vehicles, the common solution is to use an inductive loop detector. An electrical wire is placed in the road underneath where the first vehicle would stop. A high-frequency alternating current is run through this wire. This alternating current produces a magnetic field that can affect ferrous objects near it through a mechanism called induction. If a large enough mass of ferrous material is present, this induction effect will alter the conductive properties of the wire loop. This is then detected and transmitted as a signal to the controller that a vehicle is present. For pedestrians, the sensor is typically just a push button. For bicycles, it could be either an induction loop or a push button.
As for the second part of the question, the logic behind the programming, there's no simple answer since there are many approaches. The most basic system will switch traffic lights on a fixed timer, completely independent of traffic. This requires no sensors. It's a very simple system, which works OK for intersections that have a low traffic load.
More advanced systems will use sensor data to influence traffic light switching, but there's no single way to do so. An obvious way to use sensor data is to keep the lights green for a specific flow of traffic as long as there are no vehicles detected in a conflicting flow. But ultimately, in situations with multiple conflicting flows, it depends on the design goals of the developer of the system as well as the goals of the government commissioning it. Such goals could include considerations like giving priority green lights to the high throughput main road rather than the quieter side roads. Or a "green wave" that links multiple traffic lights along a road together to allow a pack of vehicles to progress uninterrupted. Or encouraging/discouraging certain modes of transportation by prioritizing bicycle or pedestrian traffic over motorized vehicles. Or allowing public transport vehicles (bus/tram) to override the active signal planning (either by shortening the current phase to reduce the stopping time of the bus/tram or by immediately switching phase to give the bus/tram unobstructed passage through the intersection). | 29 | 20 |
ELI5: What is the difference to my body if I eat 5000 calories one day and zero the next vs 2500 for two days? | It has been suggested that the human metabolism has evolved two modes of operation, activated by calorie intake. The first is *grow mode* where plentiful nutrients are flung about the body and as suggested the body replenishes itself. The second is *repair mode.* Activated by a lack of calories, the body scavenges nutrients left behind from *grow mode,* such as from build-up on the walls of arteries. This may be a response to the failure of the hunt, when protein and calories are scarce but vitamins and minerals are still available from more plentiful vegetation.
Modern humans in developed countries may be at risk of remaining in grow mode throughout their lives and never entering repair/scavenge mode, and then die of blockages caused by years of nutrient build up. | 59 | 111 |
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ELI5: Why do most birds bob their head back and forth when they walk? | It’s either a product of the birds visual fixation or depth perception. A lot of birds’ eyes have non overlapping fields of view which makes them hard to tell how far away things are. They use motion parallax to solve this by bobbing or turning their heads. | 75 | 58 |
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ELI5: Why is 3D printing becoming seemingly more viable for creating mechanical and moving items (such as prosthetic limbs) compared to whatever existed before 3D printing? | It allows for there to be specific parts made a certain size without having to make a mold to create it in. Quality prosthetic legs are created to fit a persons body part perfectly, and having a 3d printer makes it as simple as designing something with a computer program, and having a 3d printer. The materials and labor involved are almost nothing compared to what used to be done. | 23 | 43 |
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ELI5: Why does a new pair of glasses temporarily distort your depth perception? What causes this? | Glasses have two effects: focus, and magnification.
The focus is what you want to change. The reason you need glasses is that your eyes are miscalibrated, and they need a focus adjustment.
The magnification is a side effect and generally not wanted. It's the reason that people with powerful lenses look like their eyes are either way too small (nearsighted) or way too big (farsighted) - the lens is changing the apparent size of their eyes. The reverse happens, too: your new glasses are putting objects in focus, but they're also distorting their apparent size. If you're nearsighted and you just got a more powerful prescription, objects look slightly smaller than they used to. That messes with your depth perception, because your brain thinks everything is slightly farther away than it is.
The depth perception distortion will go away as your brain adjusts to the new relationship between how big something looks and how far away it is. | 133 | 347 |
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ELI5: How do hackers hack? | On the most basic level, they find a flaw or weakness in a system and exploit it. For example, the software that runs websites communicates with other computers. Sometimes, if you send it something it didn't expect to receive, it will work in an unexpected way. You can take advantage of that. | 27 | 32 |
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ELI5:What is postmodern ethics? | Postmodern ethics is way of approaching ethical dilemmas by examing the context and narrative. Generally speaking postmodernists tend to have a much narrower belief in freewill and so they feel that true questions of ethics need to be adressed at a higher more contextual level.
This would mean that theren
is no absolute or objective right or wrong, but rather many different rightnesses or wrongnesses depending on culture, situation, and narrative understandings which can change over time.
To help understand, this stands in contrast to a modernist. view of the world, which sees a continuing thread of objectivity running through the fabric of society and culture stretching back centuries. A moral story that occurs in many different situations and can be multifaceted, but is ultimately objective and unchanging.
Postmodernists also are descriptivist and tend to explain the way in which choices that are made can become moral or immoral. Modernists prefer to prescribe the correct view of morality in different situations, and evaluate the correctness of choices.
Postmodern ethics also spends a lot of time concerned with how powerless ppl make ethical decisions against ppl in power.
Postmodern view of ethics read the novel Things Fall Apart | 12 | 17 |
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ELI5: Why is the US college tuition so high? | And where is the money going? Are all colleges private? | Price discrimination. Those who can afford to pay, do so. Those who can't are given various amounts of financial aid to lower the price to a more reasonable amount.
At least it works like that ideally. In actuality many people have to take out loans, although by going to state schools you can limit those loans to well under $50k. But making all college free would just help the rich more than anyone else, since they pay by far the most college tuition. | 22 | 69 |
How is account ID generation handled at a massive scale? | I was pondering about this question in the shower this morning. Anyways, from what I understand in general on most services when a new user joins the platform they are assigned a unique account id. Now what I was wondering is how massive services like Facebook, Tinder, Twitter, etc. which could have thousands of users trying to sign up at once, handle this account id generation? Is it just random number generation? How do they prevent duplicates from occurring if it is just random?
I am struggling to comprehend how they could effectively prevent duplicates at that scale, I could understand at a small scale it could just be a simple blocking process to easily prevent duplicates, but this can't work at scale... or does it? | Depends on what you mean by "at scale". If you can build a service that is only responsible for assigning new account IDs and nothing else, then even thousands of requests per second is no big deal for an off-the-shelf database on fairly cheap hardware. Just use an auto-incrementing key and be done with it.
A significant fraction of understanding how to use "big data" and distributed systems is knowing when they're overkill. | 12 | 18 |
How can radiation cause burns? | I wouldn't guess it transfers much heat so why does it cause skin "burns"? | Others have responded in complex terms, but here is a very simple one.
Radiation kills cells by destroying their DNA. The body reacts as best it can. The results look like a burn because it's the same response. Just in this case the cells aren't physically destroyed by excess direct heating. | 140 | 114 |
Neoclassical Economics on Slavery? | I'm currently writing a research paper regarding the situation of slavery in Dubai, where workers from Bangladesh pay to be brought over to Dubai only to have their passports and documents stolen and be forced to work in slave like conditions.
Part of this research paper involves exploring what different economic theories would say about the issue. I have a basic understand of neoclassical economic theory, but I'm unsure of what exactly they would say about this situation.
Neoclassical economics argues for free markets, correct? And under this there would generally be no government rules about business', their behaviour and who can make what etc. So essentially as long as the slave labour was able to help the market reach equilibrium it would be viewed as acceptable?
Can someone help me out here?
EDIT: I've noticed that /u/zawamark is being down voted on a few of his comments. They seem to make sense, can anyone elaborate on why they disagree? | It is generally recognized that even a "free market" involves some kind of institutional framework - notably to enforce contracts. This particular part:
> be brought over to Dubai only to have their passports and documents stolen and be forced to work in slave like conditions
strikes me as fraudulent behavior, as the workers are misled as to the actual terms of their contract and are then prevented from either getting the original contract enforced or quitting their jobs. From a neoclassical perspective, they expected X (which subjectively maximizes their utility) and instead got Y (which does not). | 13 | 19 |
How do scientists figure out how an extinct language sounded like? | Decoding an extinct language is amazing. I wonder even if we discover the meaning of symbols, how do we know what sound was associated with that symbol? | From /u/voikya
"Lots of ways. Here are some examples:
Poetry—poetry, puns, and other sorts of "language play" often directly involve the sounds of spoken language. Look at English rhyming poetry from the 16th-18th centuries, for instance, and you'll often find a bunch of rhymes that don't seem to work, such as rhyming something like "love" and "move". This sort of thing implies that the words rhymed at the time. Similarly, we can learn about things like stress from poetic meter.
Misspellings—even people 2000 years ago misspelled. Someone a thousand years from now could see that "should have" is often misspelled "should of", and could reasonably conclude that both phrases are (at least in some contexts) pronounced identically.
Speech/Writing Guides—on a related note, even people 2000 years ago were annoyed when other people misspelled or used "improper" grammar or pronunciation. There are several well-known pronunciation guides for Classical Latin that simply list the ways people pronounce words "incorrectly" and how they should properly be pronounced.
The Comparative Method—one of the most important techniques used by historical linguistics, this essentially entails combining our knowledge of how sounds tend to change in languages with our knowledge of existing descendants of the language in question. As a simple example, we know that in Vulgar Latin (the language of the common people, as opposed to literary Classical Latin), the consonant H was frequently dropped entirely, as is evidenced by the fact that all of the Romance languages have lost Latin H (and it is far more likely that this consonant was lost back when everyone was still speaking the same language, rather than positing that the exact same change happened individually in each of the Romance languages).
Borrowings—when a word in Language A is borrowed into Language B, it is now (usually) exempt from any future pronunciation changes in Language A. Both "castle" and "chateau" come from the French word, but were borrowed into English several centuries apart. The much older "castle" makes it clear that the French word originally started with a /k/ sound, even though the modern French word begins with /ʃ/ ("sh")." | 74 | 227 |
ELI5: What exactly does "cash" mean? | For example when you win the lottery in all cash. Or on flipping house shows where they buy houses all cash. When i think cash i think of real physical cash. | >For example when you win the lottery in all cash
Lotteries generally have two ways you can accept your winnings.
1. An annuity for X years. Basically, the lottery commission invests the money, and pays you a yearly amount that, when added up over X years, equals the size of the jackpot.
2. Cash. You're not getting actual, physical notes and coins. You're getting a check that you can deposit at the bank. This amount is less than the total jackpot size, because they don't actually have the full amount of the jackpot, which is calculated based on what they can pay you over X years while investing the money.
>Or on flipping house shows where they buy houses all cash.
They write you a check.
In situations like these, "cash" means "you get all of the money right now in some form". | 22 | 19 |
ELI5 What is actually happening during acupuncture, does it actually work ? | In Acupuncture and in most of traditional Chinese medicine, there is a belief that an invisible life force (called qi) flows through our bodies using certain pathways (called meridians). Illness is generally caused by an imbalance in qi within our bodies, so acupuncturists stick needles at certain meridian points in the body to balance the flow. You can think of our body as a series of pipes, with qi being the equivalent to water, and the needles as valves. If there is something wrong with the water flow in any area of the body, then you manipulate the valves until the water flows correctly.
Whether any of this works or not, is the real question. Right now, there does not seem to be any conclusive proof that acupuncture is actually effective at what it does, so it is often considered a form of quackery. | 25 | 26 |
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Since in nuclear fission a very small amount of matter is converted to energy, is it Theoretically possible to create matter from energy and have we done this? | Yes, creating matter from energy is perfectly doable.
One example would be particle accelerators such as the LHC. In the LHC, proton beams are accelerated and thereby given a very high amount of kinetic energy. These highly energetic protons collide and produce various new particles. The combination of newly produced particles often has a higher mass than the 2 protons that collided to form them.
Consider for example the production of a Higgs boson. The Higgs boson was found to have a mass of 125 GeV (giga-electronvolt), while a proton has a mass of 938 MeV (mega-electronvolt) or slightly less than 1 GeV. So the 2 protons that collided to create a Higgs boson have a combined mass far smaller than the mass of the particle that was created.
And this is possible thanks to the fact that the protons had such a high amount of (kinetic) energy going into this whole mess. | 154 | 135 |
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Intuitive explaination on why colinearity blows up the standard errors of the regression coefficients | In Linear Regression, why does colinearity (or multicolinearity) increase the standard error of the coefficients' estimators ? Mathematically it is because of the Variance Inflation Factor, I know this, but intuitively, without the maths, why ? | The job of regression is to identify the independent contributions of each predictor on the outcome variable. Correlation among predictors makes it hard to distinguish each contribution. That difficulty leads to the inflated variance of the coefficient estimates. | 15 | 19 |
[WH40K] Is Ork technology, in the smaller sense (shootaz or battlewagons) possible? | Let's say you were in a junkyard, scrap metal, electronics and parts from most household appliances and servicable parts from 1 of each type of car (SUV, 4-door, truck). Could you recreate Ork technology without the innate warp ability they have? | Some aspects you could create fairly easily. Lots of junkers and home survivalists can make your typical Mad Max-esque combat vehicle, which is what most Ork trukks are. And I've seen more than one gallery of someone taking an old bulldozer and turning it into a tank.
Guns would be a bit harder. "Looting" weapons would be easy, but trying to build/upgrade them is mostly out of the question. Don't think you could build a tank gun for your bulldozer tank... maybe a flamer, though.
Red won't make this stuff go faster. | 26 | 17 |
ELI5- why do most honour killings involve murdering the victim? Why not kill the rapist instead? | In such cultures women are viewed as property, to be bought, sold, or traded. The honor killing is in retribution for the perceived dishonor of allowing themselves to be raped, as it damages or destroys their value to their male owner.
It is fucked up. | 65 | 48 |
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[Terminator] If Skynet could just pump and endless supply of Terminators out of a factory to hunt and kill humans, how could humanity ever hope to keep up? Wouldn't the human population just have steadily declined over time until they were virtually extinct? | It seems like every lost soldier is one fewer human to help fight the machines but every lost Terminator meant very little as another could replace it. So how did the humans keep pace with Skynet | At its most basic, making more humans mostly just takes food, water, shelter, and time.
To make more Terminators, Skynet needs metal, silicon chips, power sources, vats to grow the flesh, and all kinds of other supplies. And it needs factories to put it all together. Any of that can be sabotaged by the resistance. | 141 | 222 |
ELI5:Is there truly such a thing as a "fat gene"? If so, does that mean people can become obese if they eat a normal amount of calories? | There are some indications that some genetics, and/or medical conditions, may contribute to some amount of increased weight gain. However, the amount is often dramatically overstated, and minor relative to diet. | 54 | 58 |
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ELI5: Why do all living creatures have such wildly different life expectancies? | Basically every living creature only has to live as long as necessary to achieve maturity, find a mate, reproduce and optionally care for its offspring for a while. Reproduction has to be repeated as many times as is required to avoid population decline, taking into account the offspring mortality rate which is normally quite high. Any living time after that is just a free bonus and is not maintained by natural selection. It’s just there. So life expectancy of a species depends on how much time is required for this species (on average) to complete doing all the things above. | 23 | 23 |
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When you "burn fat" how exactly do you loose mass? | Do we sweat more, poo more, per more? | the main source of sustainable weight loss is through breathing. You can of course lose mass by sweating and peeing, but that is not sustainable as most of that loss is water which needs to be replaced for proper function of organs. Weight loss (specifically of fat) follows the same formula as burning gasoline:
fat molecules CnHmO6 (rough chemical formula of a component of fat) are oxidized by O2 to produce CO2 and H2O. The CO2 is expelled through breath, the H2O is, as mentioned before, added to the overall water balance of the organism. Since the majority of the mass of the fat molecule is stored in the Carbon (roughly 4-6 times more massive than hydrogen on a weighted average in fat molecules), the majority of the mass is lost through production and exhalation of CO2. | 1,632 | 1,354 |
ELI5: How do screens smoothly scale resolutions that aren't multiples of each other? E.g. playing 1080p or 720p video on a 900p screen, or reducing my phone's resolution from 1440p to 1080p? | There are complex algorithms that will combine pixels with their neighbors in certain ways. If you have a higher resolution screen being scaled down such that a pixel should be 70% one color and 30% a different color, the calculation would yield a combined color of the appropriate proportions. | 20 | 15 |
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ELI5: Russia's close ties to arab nations | During the cold war, there were essentially three options for small countries:
1) Be friends with the United States
2) Be friends with the USSR (most of which is now Russia)
3) Go the "neutral" route, like India, although this wasn't always guaranteed. If a small country wanted to be neutral there was a good chance they would be invaded by either the USA or USSR, to make it be their friend before the other side could.
This led to many "proxy" wars, where one side would fund rebels in a country allied with the other side, trying to get it to switch over to their side. Examples include Vietnam, Cuba, and Afghanistan. If one side supported a government or rebel group during the Cold War, and that government/group eventually lost, the people living there today tend not to be friends with whoever was involved. This factor was already discussed by u/YourResidentRussian, although obviously with a pro-Russian bias.
Also, today countries basically only have two options:
1) Be friends with the USA.
2) Don't be friends with the USA (this means you need an alternate big-country friend, usually Russia or China)
So many Arab countries actually took option #1 and are friends with the USA, including Saudi Arabia, Jordan, Israel, Kuwait, Qatar, Bahrain, Iraq and Afghanistan (those last two were not really by choice).
Syria and Iran, along with a few others, went with option #2, largely because they have some historical reason to distrust the USA, and may have had Cold War ties to the USSR. Its not necessarily that they want to be great buddies with Russia, just that they are NOT friends with the USA, so Russia was one of their only alternatives. | 24 | 42 |
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ELI5: Why do humans subconsciously move body parts to music? | Music is very ancient for humans. Music was developed before our language centers were fully developed. We were making flutes before we could call it a flute. Our brains are hardwired to respond to a beat. Tapping your foot is just one way your brain responds to the beat. | 10 | 15 |
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ELI5:How do plants generate heat, how to they stop freezing when the droplets of water that are on them are frozen, when they plants are made up, mostly of, water? | Plants generally do not generate meaningful amounts of heat. They deal with freezing temperatures by: dying, like orange trees; freezing, but in a way that doesn't cause permanent damage, like most deciduous broad-leaf trees; or pumping themselves full of antifreeze, like most conifers. | 15 | 20 |
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ELI5: Why can I pick up my little brother, who weighs around 100 lbs with no issues, but I struggle just trying to get a 50 lb weight off the ground? | A big thing to remember is that when you pick people up, they are actually helping you. When picked up, people uncounsciously shift around to get their center of balance just right so they wont fall, and it helps out the lifter.
If you tried picking up an unconscious or asleep (or dead) person for example, you would have a veeerry hard time because they are no longer helping you and their center of balance shifts wildly. | 1,241 | 1,130 |
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[Matrix] Why didn't Neo and the gang carry C4 or hand granades? | That way, whenever there was a change in the Matrix (ie. a window being changed to brick wall), they could just blast their way out. | Your knowledge of the matrix is based on the rules they've told you. Free your mind. Yes, c4 could blow through a brick wall if it followed the usual rules. But they can change code. They could line the bricks with explosives and shrapnel. They could increase the strength of the materials a thousandfold. All you know is the code changed. You don't know *how* it changed. It's best to stick to what you can *see*. It was easier to run than take the chance.
That being said, how often do you get deja vu? They don't change the code too often. | 139 | 213 |
[BSG] If the Twelve Colonies possessed FTL jump drives that were capable of crossing significant portions of the galaxy, why didn't they expand further before the Second Cylon War? | I understand that jumping long distances is dangerous, but surely they sent explorers or surveyors to new planets at some point?
The colonials have been spacefaring for at least 2,000 years after all. | The Colonies were extremely unusual in that they were several habitable worlds in really close proximity to each other. In contrast, it took weeks of searching further out from Colonial space than they had ever gone for the Galactica to find ONE barely habitable planet.
Calculating jump parameters is also an involved process which has some inherent risks. You can jump to nearby stars using telemetry gained from ground and orbital telescopes, but it lacks exact precision and most stellar bodies are almost impossible to detect, such as asteroids small planets, comets etc. This seems to be the type of recon Raptors were designed for, but they lack the sensitive viewing systems to extensively survey entire systems.
Basically, it seems to be a measure of time... They'd have to calculate reliable jump-coordinates from telescopes, send a Raptor to do a cursory sweep and determine safe coordinates for a larger jump, then send in heavier survey equipment both to survey the system but also to collect data for further jumps. That type of work is time consuming, and rather expensive.
This wasn't so much an issue for the Galactica, since they largely threw caution to the wind for the sake of survival, but the Colonies wouldn't have been so desperate. In fact, between the First and Second Wars they seem to have become increasingly arrogant and bureaucratic. | 106 | 133 |
ELI5: There is a border dispute between Egypt and Sudan where there is one location which neither country is claiming. Is it possible for me to go and claim it as my own? | Conceptually you could, but you are unlikely to have your claim recognized by an international body. That would put you in the same boat as anyone else making random land claims, and you would probably get shot by some random goat herder. | 11 | 15 |
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ELI5 Why are camera lenses always circular? | Camera lenses are not perfect. They don't focus all light colors the same way. You get tiny rainbow effects on your photo.
The further from the center light goes through, the bigger the flaws. A circle is the ~~optional~~optimal shape with no corner outlier points further away from the center.
Google Chromatic Aberration and look at images to see examples of what happens at the edge of a lense. | 41 | 31 |
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Why are humans capable of forgetting things? | Why do we lose the ability to access memories? Are there any creatures that can remember everything? i.e. elephants | Remembering everything is not practical from am evolutionary stand point.
There are after all, physical and biological limitations. Which include space, time, neuron and synapse length among others.
Sifting through countless useless memories requires neurons to communicate with one another in ways they wouldn't have to otherwise. This uses up time, space (more synapses), ATP and all manner of neurotransmitters, which is not cost effective.
So the brain picks the useful things and stores them, all the useless crap is not retained. The more a memory is used, the more important it is, so the stronger it gets. The mechanism by which the brain does this is not fully understood yet, but it is easily observable.
You have to remember that every system has limitations, and everything is a careful balance between variables. In this case, it's a simple relationship (in principle) between the cost-benefit of remembering everything vs remembering only the most important events. | 22 | 44 |
Is there a theoretical limit to the size of ocean vessels? | There are many non-theoretical limits:
Economics. (Cost to build, staff, fuel and turn a profit.)
Port or passage size. (Not simply depth/width of port, but cargo handling limts. It doesn't do your passenger/cargo company much good if it takes weeks or months to load and unload. It also needs to fit under bridges or through canals or breakwaters. Include tugboat size under general port size issues.)
Engine size - (which is both a subset of economics, but has its own limts as well for maximum engine size. But you can theoretically add more smaller engines.)
Material strengths and choices. (This is less important than the above two issues. Google: pykrete to see how to make massive ships out of ice and sawdust.)
And the final hard limit may simply be the curvature of the earth, and any assymetrical gravity loads the ship may experience due to the not-so-uniform structure of Earth and accompanying gravity field.
But the theoretical upper limits for a floating, moving ship are absolutely, staggeringly huge. Look at icebergs for examples. They've documented floating icebergs that are the size of small countries or US states. They're big enough to build several cities on and are measured in dozens or hundreds of miles wide and long, with hundreds of feet of ice above water. If you made a ship out of solid pykrete that size it would likely last for a hundred years.
There's also nothing really stopping someone from building a ship the size of, say, California if you can find a place big enough to float it and it weighs less than the water it displaces.
Moving it around with fossil fuels would probably be too expensive. You might be able to sail it around, or use solar or nuclear for electric drives.
But moving a ship the size of California around would also probably cause, uh, some minor catastrophes like tsunamis, altered ocean currents, altered wind patterns and more. | 924 | 1,636 |
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US Presidents should serve one six year term without the ability to be re-elected. CMV | As it stands, a four year presidency is a short amount of time to initiate new policies, test to see if those policies work, and foster new plans should they need re-adjusting. Thus, to make any long-lasting impact, each president strategically expends their political capital to make just enough changes as to satisfy their base, while constantly keeping an eye out for re-election threats and opportunities. It's only in one's 2nd term do we really get to see a President in their true form, without their constant pandering to the masses.
I submit that a single six year term, without the possibility of re-election, gets the best of both worlds. We get single-minded leadership focused on national priorities, without ever being swayed or influenced by the temptation to curb their goals in order to foster votes. Six years is enough time to implement positive changes, but also long enough to undo mistakes from the previous presidency, should that be necessary.
I also submit that amending the constitution to make this change would be relatively straightforward and few would argue against it. | How would changing the executive power, affect the legislative? The congress is the problem when doing new policies, not the president. The president could be God almighty, and the congress would still bicker and crap on changes in the name of money. | 35 | 79 |
Why are things generally cheaper in poorer countries? | For example I got restaurant meals in Cambodia for like $5. I thought the reason that these countries are poor is that they are less productive meaning there are fewer goods and services to go around so wouldnt that mean everything should be more expensive?
Also I understand that the $5 restaurant meal is probably a higher % of the average cambodian income than a $15 meal is for an average american, but that still raises the question of why my income can go farther in a country like Cambodia than in America even though America is more productive. | terms to look up: purchasing power parity
i think you touched a bit upon it in your second paragraph, $5 for a cambodian is a higher % of their income than what $15 would be for an american. part of it is straight up currency exchange rate, and the differences in those (for floating regimes or semi-floating) are due to supply and demand for that currency. the USD will be more in demand than whatever the currency in cambodia is, simply for obvious reasons like more people travel to the US and exchange goods in that currency than they would in whatever the cambodian currency happens to be.
but another difference then is purchasing power parity, which is an index to measure how much a certain basket of goods costs within any market. this basket contains non-tradeable services alongside goods, and reflects the cost of living in a particular area. with goods that you can sell across borders, you are likely to have similar prices, simply because any attempt at a lower price by one country will be met with increased demand for that country, less demand in the others with the subsequent lowering of prices (the typical supply and demand forces you see in micro environments, in a hypothetical ideal world).
but then when you consider non-tradeable services and goods, these can't be traded, because by definition many of them are services provided locally by the local labor force. of course, with globalization you are starting to see more transfer of services between borders, especially with online education or tutoring. but things like haircuts, or restaurant meals, that require local labor? those are non-tradeable.
a meal then in cambodia is $5 because the cost of its labor is much less than in the united states. why is it that in the united states you have to pay a worker $12 an hour, and in cambodia only a $1? this is where difference in productivity come in. because america is more productive, the opportunity cost of one hour of labor is worth more simply because you have more productive alternatives. you can work in a factory and produce more value to your employer in one hour than what a worker in cambodia could do. furthermore in america you have so many options to be productive, you can enter and exit the labor force with high liquidity. there are minimum wages as a price floor for labor. an american laborer is coveted because they have the choice in working at another chain, or do something else entirely with their hour of labor. as you said, they are more productive, so they can produce more in the same amount of time. it's not just about pure labor skills (though in this case, yes, an educated and literate work force), but also technology and capital.
meanwhile in cambodia, it is less productive. they produce less in that same hour. it is not about some pure intrinsic "lesser value" but simply their work force might not have the same basic general education as the US (do they have universal K-12?) their labor might not be literate, they cant just read and follow directions to handle machinery or procedures one would use in a more advanced work force like the US. they might not have the same level of productive technologies and capital to be productive. so one cambodian worker might make much less in one hour than one in the US would. that is reflected in the wage.
why would a cambodian accept $1 per hour? (and btw im just using the $1/hour as an example, i dont know the actual number) well if there are less opportunities, as there would be in a less productive society, then you might settle for that little. when there is less capital flow in that country, less opportunities arise, and with a large workforce? they will simply be paid less because overall they will be less productive.
ultimately, when you think about a country being "more productive" than another, that goes for its factors of production, which include labor. and that labor is also subject to market forces, and that will differ between countries because the level of productivity differs. | 50 | 58 |
ELI5: Since Jews are such a tiny percentage of the population, how are they represented so well in elite groups? 13% of Nobel prize winners, 48% of US billionaires, etc. how is this? | Jewish people originated in an area where most people were not allowed by their religion to loan money and charge interest. Jews could, and this lead to them becoming bankers and becoming quite wealthy. Wealth tends to perpetuate wealth, as well as education which then perpetuates wealth. A head start means a lot, so it just compounds (like interest). | 59 | 38 |
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ELI5 : Why aren't we hibernating in winter like most of other mammals ? | Humans evolved in a tropical part of Africa, and are adapted for existing in that sort of environment. We can adapt ourselves to live in colder environments, but have to provide shelter and clothing to survive there. You can live naked in the jungle with very few tools--ask any of the tribes all around the world who pretty much live that way. For the same reason, we're never going to be able to hibernate, we simply did not evolve that way. | 80 | 74 |
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ELI5: How does a machine “make something cold” | I understand the highschool basics of the physics behind energy and heat, so the concept of a machine turning electrical energy into heat is easy to wrap my mind around. The idea of “something making something cold” was explained to me as an energy deficit being fixed, like if you put ice into water, the ice takes the heat and energy out of the water until the ice turns into water also. How does something like a freezer do this to the air inside? How does a machine receive energy to then take that energy away? | A freezer is effectively heating up the outside air with the heat that exists in the freezer by absorbing and concentrating and moving that heat around via thermodynamics and fluids under different states and pressures. Basically, the most basic principle is that for a change of state to occur requires a lot more energy than simply raising its temperature. So as a liquid changes to a gas, it must absorb a lot more energy than simply warming up the liquid. Now, take a particular substance that changes from liquid to gas at a convenient temperature and pressure range for your application, and squeeze it (in liquid form) into a low-pressure space where it is forced to become a gas because of the pressure. Changing to a gas requires a lot of energy, so it absorbs all the heat around it to do so. Now as a hot gas it can move to a different location where it is cooled down and becomes a liquid again. This is called the refrigeration cycle. And it’s how air conditioners and freezers work. | 69 | 50 |
Does Pluto have a liquid nitrogen ocean under it's frozen nitrogen surface? | The reason we find liquid water oceans under the ice of certain worlds is because solid water ice is less dense than liquid water, and so ice can float over a water ocean and both maintain its pressure and insulate it to retain some heat. If there were somehow a liquid nitrogen ocean under Pluto's surface, the solid surface would sink below it, and the liquid nitrogen exposed to vacuum would either freeze or evaporate. | 32 | 30 |
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Has the string theory been validated by any experimental evidence like from the LHC? | Are there better contenders for the theory of everything?
I know just the basics of what the string theory is, that is using vibrating strings and extra dimensions to explain all the different forces and particles. I come from a medical background, so please excuse any gross misunderstandings of the concept. | Some required aspects of string theory have been constrained by the LHC.
1. String theory requires more than the 4 dimensions of space time. The size of the proposed dimensions has been constrained as if they were larger we would have seen things that disagreed with the standard model.
2. Super String Theory requires super symmetry. Low energy or "Natural" Super-symmetry was not found. String theory is compatible with any energy of super symmetry below the plank scale however. So lots of proposed models of string theory were shown to be incorrect, but not the general model of the universe.
This has caused some worry in physics as it now appears that string theory will not have any interaction with experiment for the foreseeable future. That may change with gravitation wave astronomy, but so far there is zero experimental disagreement with General Relativity. | 16 | 22 |
I learned in Biology class that proteins/enzymes unfold and lose their function when they are heated up. How do steaks stop have so much protein when cooked? | Edit: wow, came back from work and got some great answers! Thanks everyone! | Protein shape ultimately gives rise to protein function. The proteins in steaks don't still need to be functional to be proteins. A denatured protein is still a protein, and if you have somehow broken it down into its constituent amino acids your body can still take those amino acids and build proteins out of them. | 360 | 433 |
Why are there thousands of blackbirds flying around, but colorful songbirds are such a rare sight? | The simple answer is natural selection.
The traits that the "boring" birds have help them live longer in the wild in comparison to colorful songbirds. Colorful songbirds can only survive in areas where there is minimal predative pressure. | 11 | 65 |
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As someone gets more obese, do their actual skin cells stretch or do they replicate fast enough to keep up with the increasing surface area? | A follow up question would be:
If the cells stretch more than they replicate, does this mean that there is a lower concentration of nerve endings? Would stretched skin around large fat deposits be less sensitive to touch? | Their skin cells divide to increase surface area. Individual cells have limited elasticity and if they simply stretched to cover the increased fat tissue underneath, it would be like blowing up a balloon (e.g. getting thinner). In fact, more than just the skin cells help cover the area. Blood vessels, connective tissue, the fat cells themselves all have to accommodate the increased tissue volume. As a corollary, when someone has massive weight loss, you can see the large amount of loose and excess skin. The signals from the body to make the skin cells divide to cover the larger area can't just reverse instantaneously (you also have issues with looser connective tissue, loss of elasticity of various components, etc.) so now you have large folds of skin hanging around.
EDIT: Forgot to respond to your follow-up. You can have issues with less touch sensitivity but it's hard to say that it's just because of less nerve endings (your nerves can make new connections so you still have touch sensations). More often, losing feeling in really any part of your body (bodybuilders with massive skeletal muscles, areas of fat deposits) is a combination of factors like poor blood flow to the cells rather than just not enough nerve endings. | 2,581 | 7,452 |
Scared about getting a job as a programmer. | Hello,
Working as a programmer is genuinely scaring me. I love solving problems and trying to find their best solutions, but when i think about getting a job as a programmer, i'm scared. Most of the jobs i see aren't really involve solving problems, but much more arguing with a language to make it do what you want. Take as an example Web Developers (i had an internship in a webdev company this summer, and this started my thoughts), to me it looks like they're spending most of their time writing solutions to problem they've already solved over and over. And if i think about jobs that actually involve solving problems i start to think about deadlines, having to write bad code on purpose to meet them and even to be irrepleaceable and get job stability.
This is definitely what i don't want to do, and i'm pretty sure it'll bring me in depression pretty quickly.
What i want to do, is spend my time solving problems, find new ideas, improve programs so they're easier to use, faster, lighter, without all the bullshit that most programs today bring with themselves.
I was thinking Academia could be my thing, but i'm not even sure if i'll be able to enter University, because as much as i'd want to, i don't really have enough money, and i don't even know what working in Academia really is like. But if i think i'd like it, i'm pretty sure i'd start doing something about the money.
So, what do you think that could be my possibilities? | I really think you should try to attend university if you really want to pursue a career in the CS area. There are many scholarship and loan opportunities for those in a less than great financial situation. University will help you discover the different types of careers.
Research may be what you're looking for but you won't get there in academia or business without a degree and likely a masters/phd of you really want to pursue research. | 18 | 33 |
[Fallout] Why does pre-war money still have value with traders 200 years later? | Did the US not abandon the gold standard in the Fallout universe? Or do merchants just like collecting old money for historical/sentimental value? | Money is a paper and cloth mixture, which can be useful for crafting or as firestarting material. And yes, lots of people like collecting it for sentimental value. Just look at the craze around rare bottle caps. | 47 | 21 |
[MCU] Who/what decided Red Skull's penance? And why? And why only him? | The only clue we have is that the Space Stone cast him out. Okay, makes sense that one stone would connect to another one. But why? Is it because he abused them for power? Lots of MCU villains have done that and been fine. It's not because he directly touched it, because he didn't. There was a cube of something surrounding it. Besides, Jane Foster *did* directly touch the Reality Stone and all it did was try to kill her. It's not because he wasn't strong enough, either - see Jane Foster. Is it because he tried using it for raw power when its purpose is to move through space? Did it maybe just send him through space because that's what it does, and the Soul Stone did the work? Did anybody else in all of history get judged like this? And how did Red Skull know any of this, anyway? | The Space Stone itself is said to possess some form of sentience, unique among the Stones. People who study it closely will refer to it as "she" and keep imaging the Stone purposefully trying to show people stuff. When the power was turned off on the device uses to harness its energy. the Space Stone turned it back on by itself.
So, the Space Stone decided Red Skull was abusing it, and took matters into its own hands to punish him. | 30 | 28 |
What features of an aircraft and the aircraft's engine allow an aircraft to supercruise at supersonic speeds? | This mostly comes down to engine selection and inlet design. Each stage of the turbojet/low-bypass turbofan engine (low pressure compressor, high pressure compressor, burner, turbine, afterburner, nozzle) have to be designed to be efficient enough to sustain supercruise on the fuel the aircraft has. They also need to be optimized for supersonic flight. This can come down to nozzle control to make sure the exhaust is not being over or under expanded. Also, the inlet design has a massive impact on the overall efficiency of the engine. As the aircraft gets above mach 1, there have to be shock waves that slow the flow into the engine so the air entering is subsonic. If the inlet was flat like a 737 inlet, it would have a single normal shock to slow the flow down. That is inefficient and it would be better if there were multiple oblique shocks before the normal shock. This is why aircraft like the F-15, F/A-18 super hornet, etc. have angled inlets. The number of shocks and how closely those shocks align with the inlet at the supercruise speed determines the efficiency of the inlet. The inlet can be a moving piece that adjusts its angles and can therefore adjust for its speed or they can be fixed and have a set supercruise speed.
There are other ways of doing this too. The SR-71 has conical inlets that effectively do the same as a ramped inlet but in a circle. It also has engines that can almost completely switch from a turbojet to a ramjet. Ramjets use the high compression from the supersonic air to compress the air instead of the compressor blades of a turbojet. They suffer from the fact they dont work at low supersonic speeds and below so they need a way to get there either by converting from a turbojet or by being carried to the necessary speeds by something else. | 13 | 16 |
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ELI5: What is happening when time appears to be passing slowly, or faster than usual? | Why do we sometimes sit in class waiting ages for 5 minutes to pass, but when I sit down to study for a test and its already 2am? | How you perceive time deals with how much information you are taking in or how involved you are in a situation. Time flies when your having fun, or in your case, studying. Your brain is busy with things that don't involve keeping track of time, so it doesn't.
There is prospective time and retrospective time. Prospective time is how you perceive time when you are studying or looking at the clock waiting for time to pass. Retrospective time is looking back at how long it actually felt. While doing something interesting or involving, your brain is taking in heaps of information and not keeping track of time. But when you remember events or occurrences, the more information you have, the longer it seems. For example, prospectively, while going on an exciting trip, time seems to fly. Retrospectively, an exciting trip of two days can feel like a week.
| 17 | 61 |
[Harry Potter] If we, wizards, can literally generate/duplicate matter/objects/energy at will, what is the point of selling/buying anything that is not information/intellectual property? | The title says it all. Like, why do we even have an economic system? Most of our basic resources, like food, water, clothing, space, shelter, and everyday objects, are infinite because we can generate/duplicate them. We can even generate some magic items for god's sake! And most if not all the labour can be done with magic, especially if we integrate muggle technologies. What is the point of money them? Should we not be truly a Communist society, as pretty much all members have access to the means of production (e.g. the wands)?
I mean, besides the hair of Scarlet Johanson (for, hm.... polyjuice reasons...), what other material product would I had to seek in the market during my lifetime? | Can't duplicate magical goods, and Gamps Law has some applications to what you said. But the main thing is magical goods.
Not everyone can perform all the interesting item creations, broom makers charge a premium. Want a proper owl? Wizarding currency. Potions? Wizard currency. Specialty services? Same.
The list goes on. | 63 | 54 |
ELI5: How do "long exposure" pictures work? | I've recently seen a lot of these and they seem so cool. | A camera-- to simplify-- takes in light to create an image (much like our eyes).
A long exposure just keeps that eye (the shutter) open longer, so that more light gets processed into the final picture. | 414 | 836 |
ELI5: Why after downloading some applications, do I need to restart but others work straight away? | ^ | Because some applications use low-level resources which are already loaded into memory and used continuously by other applications and the operating system as well. Since reloading that particular resource in to memory is way too hard without crashing other applications or the OS itself, the best is to make the user reload the full operating system, hence the need to restart. | 13 | 43 |
Why are legendarily high failure rates acceptable in undergraduate organic chemistry courses across universities? | I'm a university professor (not in Organic Chem) and I've always been irritated and perplexed by the low exam means and high failure rates for students in Organic Chem courses. This seems to be consistent among universities in the US and acceptable to the chemistry faculty. If my courses had these results I'd be asking myself:1) Am I wrong about what I'm successfully teaching these students, 2) Am I trying to cover too much material? Perhaps the course should be divided into 4 parts instead of two, 3) Is this subject too hard for an undergraduate to grasp. Personally, I see the legendary status of Orgo as a "weed out course" to be a shameful characteristic of chemistry curricula. Correct me if I'm wrong. Thanks. | I think organic chemistry is one of the first classes that a really smart student will run into where they need to understand rather than memorize. They will run into me of these classes during their university career, but a lot of students will take organic in their first year, when they are still super confident and reliant on what worked in high school.
So, the really smart students will manage, but it will drop out a lot of kids who don't realize how lost they really are until they have to apply their knowledge rather than just regurgitate it. | 23 | 27 |
How can I easily differentiate between Java, C++, and C#? | How can I tell just by looking at them? What makes them different and what is it about these differences that makes them good for different tasks? | Look at the top of the file. Typically you'll see:
* **Java:** `import ____;`
* **C/C++:** `#include<____>`
* **C#:** `using ____;`
If you don't see these, look for a `main()`/`Main()` method:
* **Java:** Takes a `String[]` or `String ...` argument
* **C/C++:** Takes a `char*[]`, `char**`, or `void` argument
* **C#:** Takes a `string[]` argument
The first difference you'll find in languages is where they can run. Java can run on operating systems that have the Java Virtual Machine (JVM) installed. Java compiles into "bytecode" that is interpreted during run-time by the JVM. C/C++ can run on any operating system for which there exists a C/C++ compiler. Most operating systems have a C/C++ compiler for them, but you have to compile separate binaries for each OS. C# is the same way, but C# is most often run on Windows only (there is a project called Mono that is trying to change this).
Other differences include the amount of control you get (how close the language is to the hardware versus how abstract various things are). C is pretty low-level. C++ is a bit more abstract. Java and C# are even more abstract than that, probably with Java being the most abstract of the two.
You might also find that speed is a determining factor, depending on the operating system and compiler. Typically, it is believed that C/C++ is fastest with Java and C# trailing behind, but you'll find others argue that Java and C# are just as fast.
The different languages offer lots of different features. C# has LINQ, lambdas, async/await, etc. Java also has lambdas, but not until recently. It also has global imports. C++ has pointers. There are a ton of differences. Further, each language comes with a standard library. The standard libraries for Java and C# are more built out than the standard library for C. The standard library for C++ is much closer to that of C# or Java, but it still has a way to go. | 16 | 17 |
CMV: Preventing people who aren't people of colour from portraying people of colour is also racist. | Mike Henry (a white male) has stepped down from voicing Cleveland Brown on Family Guy amid a growing call from the American public that characters of colour should only be voiced by people of colour.
But doesn't that just sound like racism with extra steps? It's basically saying that you and yours cannot do this particular thing because you and yours are not part of this particular ethnic group.
Also, shouldn't it go both ways? Should Christopher Judge (a black-cherokee male) step down from portraying Kratos in the God of War franchise because Judge himself isn't Greek?
Friends, Romans, Countrymen, change my view. | It has to be understood in context. In "the perfect world" you'd be right, but in our world the assumption here is that these roles aren't given to black people _because they are black people_ (or perhaps that the white guy has more gas in the tank in these circles because they are NOT black).
So...if you arrive at the place where you think that had YOU been black you'd not have got the role that is a black person and that a black person also qualified didn't get it because they were black, then....well....that's not cool, eh? | 45 | 100 |
ELI5: how do tide to-go sticks work ? | A mixture of acids and hydrogen peroxide help break down stain causing molecules, and it contains some molecules soluble in both polar and nonpolar solvents, allowing to wash away both polar and nonpolar crap. | 55 | 67 |
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ELI5: What is the reasoning behind how trains are loaded? | I see trains everyday and I’ve never understood how/reason behind how rail cars are organized. I see 3x fuel cars then 2x box car, and finally more fuel cars. Why not all the fuel cars then box cars? | They are generally arranged by how they are picked up and delivered. It's much easier to pull into a place and unhook the last five cars, then go to the next place and unhook the next 8 cars, etc., then to have to go to each place, unhook cars 1-6, and cars 7-12, then connect to cars 7-12, then move them, then disconnect them, then reconnect cars 1-6, then reconnect the rest of the cars, etc. | 34 | 23 |
Is there a term/concept for the way unrelated political beliefs are tied together? Like taxes/abortion. | So in the US there's only two major parties so that there's a divide set up on every issue, right? So is there a term for the way that Democrats vote in a bloc like pro-choice, more social programs, gay marriage, more taxes, no death penalty?
I just want to do more reading on that topic, but don't really know how to Google it. | You may want to search for cleavages (persistent divisions within a voting population), alignment (the formation of a coalition of interests behind one party), and dimensionality (the number of axes/spectra/predominant conflicts needed to explain a country's party system). | 14 | 24 |
ELI5: Why do different strains of cannabis have different effects? Isn't it all still just THC? | You know how with some vegetables or fruits there are a bunch of different varieties, like with apples or tomatoes, that are all technically the same fruit but maybe have slightly different tastes, colors and shapes from each other? Like how one type of apple tastes a lot more bitter than a different type, or how some tomatoes grow really huge and others only the size of cherries. All of them are from the same family, but have slightly different genetics from one another. That's pretty much how different strains of marijuana work as well. Slightly different genetics produces a slightly different plant that may have slightly different perceived effects - like how some strains give you a head rush and a bit of energy, and others give you more of a body high and can make you feel really lethargic like you just want to sink into a couch. | 14 | 37 |
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Will the perfect moral person, be happy? | Let's assume someone who every decision he takes, is the net most moral decision in every moral system that exist, will that person be the happiest person? What would be his emotional reward for his moral perfection?
Edit: most moral decision in every moral system = think of net moral utility, apply the same logic to the sphere of moral systems | I don't know what you mean by morally perfect "in all moral systems that exist"... that seems totally impossible, as some moral systems (e. g. Act Utilitarianism and Kantian Deontology) are mutually exclusive - it's totally possible that you are a formidable person according to Utilitarianism, but a monster according to Kantian ethics.
Could you maybe clarify? | 33 | 48 |
What environmental impacts would a border wall between the United States and Mexico cause? | I think one of the biggest impacts would be the alteration of water flow.
I don't think you could successfully build a wall down the middle of the Rio Grande river, which is the border, so the wall would have to be on the north side of that river, denying access to that water to all the animals north of the river. This would probably drive all the larger animals farther north in search of water and would flat out kill lots of them.
For permanent waterways that flow across the border, you're going to have to either divert them or create some sort of grate system. If you divert them, again, you're denying water resources to something.
In arid regions like this, there are a lot of ephemeral waterways that are dry 99% of the time, and full flood the other 1%. Altering these waterways would change the distribution of soil, sand and organic matter that is carried by these waterways. | 2,990 | 6,201 |
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ELI5: What causes my stomach to hurt when it’s hungry but then it “un-grumbles” and the pain goes away? | If I’m hungry for too long, my stomach grumbles weirdly; it hurts a lot and then releases a big grumble and it doesn’t hurt as much. What is this? | Your digestive tract moves food through it via squeezing it along, in an action called peristalsis. Gas bubbles or other blockages can build up in certain places and cause pain. If the bubbles are being squeezed and suddenly find a path to another region, the pressure is reduced and this movement can cause noise. In some cases when you are hungry and have a less full stomach a larger fraction of the space can potentially become air, though it may not always be related to hunger - rather gas production by your gut microbes. | 22 | 36 |
How do Chinese Citizens actually feel about the one-child policy? | I remember in 8th grade, my Social Studies teacher had an article saying something crazy like 80% of the Chinese approve of the policy because of their conditions, but I can't find *any* sources. | Not an answer, but some things to note: the policy is not universal, nor is it always effectively enforced where it does apply. Because the primary enforcement mechanism is a fine, wealthier families often treat it as a tax rather than a prohibition.
So there are (at least) two different questions implied here: *how do Chinese citizens feel about the policy?* and *how do Chinese citizens who are affected by the policy feel about it?* | 47 | 49 |
Does refraction change a ray of light's speed? | In the past, refraction was explained to me as a result of the change of speed in light when light enters a new medium (glass, water, prism) with refractive properties at an angle. This is supposedly why white light gets broken down into a spectrum in certain prisms.
* Does refraction change the speed of the light?
* Does this speed change only occur at the point of impact with the refracting medium or is the speed of the light slowed throughout the medium?
* Does the speed of light return to normal after leaving the medium? If so, how does this happen without any additional force applied to the light? | Do not confuse light with photons. They are related. Light is a classical phenomenon which has a deeper understanding explained in quantum theory by photons.
Photons always always *always* travel at *c*.
The speed of a beam of light, in classical optics, depends on the medium through which it travels, where that speed is always <= *c*. Light travels at *c* in a vacuum.
As Das_Mime said, classical light is a wave phenomenon. If you've studied waves, it should be apparent that the speed of the wave isn't really about forces like it would be talking about particles. In classical optics, the speed is determined by the medium.
As for how this is resolved with the photon model of light, it has to do with continual absorption and re-emission of photons by the constituents of the medium. If you search through /r/askscience, there's probably quite a few threads about that. | 10 | 15 |
ELI5: How can Supermarkets just flat-out rip off a product | Why can I go in and see "Frosted flakes" next the Frosties, yet they don't get sued?
EDIT- I'm not just talking about Frosties, you see it everywhere. If there's a popular product, there will also be a store-brand rip off. | First, a large portion of store brands are made by the same companies that make the name brand items.
Second, the only way kellogs could sue over frosties is if they were to emulate trademarked elements of the packaging (ie character, font etc) in a way that creates a substantial similarity which could reasonably cause issues of differentiation by prospective purchasers.....or if kellogs had patented EVERY possible process to flake corn, and coat it in frosting. EVERY possible process...because a very small alteration in equipment and procedure can be sufficient to sidestep a patent. | 46 | 42 |
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