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Sunday, April 7, 2019

What do swordfish use their sword for?

What do swordfish use their sword for?


What do swordfish use their sword for?

Posted: 07 Apr 2019 03:48 AM PDT

What mathematical language did Gerardus Mercator use to describe his projection?

Posted: 06 Apr 2019 04:10 PM PDT

In the Mercator projection, the y-position of a coordinate is given by the log of the tangent of its latitude. This was laid down in the 1500s. The concept of using functions to describe geometry came a bit later with Decartes, and the logarithm wasn't described until the next century either.

So what tools or language did Mercator use to describe how coordinates on his map could be constructed?

submitted by /u/iorgfeflkd
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What is the distinguishing factor between a forest and a jungle? Is it a climate thing? Type of trees?

Posted: 06 Apr 2019 06:07 PM PDT

If fever is used by the body to kill bacteria or viruses, does this not also damage the useful bacteria in the gut?

Posted: 07 Apr 2019 05:16 AM PDT

If you relocated a sea turtle's nest to a completely different location, would the babies return to where the mother laid them or where the human relocated them to nest?

Posted: 07 Apr 2019 04:20 AM PDT

What biological differences in some mammals allow for advanced movement very soon after birth?

Posted: 07 Apr 2019 07:43 AM PDT

For example, why can horse foals walk so soon after being born, versus human babies who require ~8-9 months before they can crawl, when horse gestation is only a couple months longer than human gestation?

submitted by /u/UPPERCASE_THOUGHTS
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Is the human ear more sensitive to certain frequencies?

Posted: 07 Apr 2019 07:51 AM PDT

I came across this website to test my subwoofers. I noticed that around 128 Hz, the sound becomes very loud compared to say around 142 Hz. I don't think the application is faulty, could it be that my ears just are more sensitive to sound at that frequency?

submitted by /u/Akainu18448
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How are entire ecosystems largely consistent between continents, but entire classes of animals therein aren't represented at all?

Posted: 07 Apr 2019 07:28 AM PDT

I was recently reading Teddy Roosevelt's The Wilderness Hunter, and an excerpt from the first chapter caught my interest:

"The untrodden American wilderness resembles both in game and physical character the forests, the mountains, and the steppes of the Old World as it was at the beginning of our era. Great woods of pine and fir, birch and beech, oak and chestnut ; streams where the chief game fish are spotted trout and silvery salmon; grouse of various kinds as the most common game birds; all these the hunter finds as characteristic of the New World as of the Old. So it is with most of the beasts of the chase, and so also with the furbearing animals that furnish to the trapper alike his life work and his means of livelihood. The bear, wolf, bison, moose, caribou, wapiti, deer, and big horn, the lynx, fox, wolverine, sable, mink, ermine, beaver, badger, and otter of both worlds are either identical or more or less closely kin to one another."

This is a really wide swathe of these biomes that has life similar enough to reside (in many cases) in the same genus and sometimes the same species. How is it that these areas can simultaneously be so similar, while in other areas - songbird populations, reptiles, etc. - they remain almost totally distinct? For instance, while both locations have rat snakes, that's an enormous subfamily of colubrids that often aren't all that similar. Similarly, both regions have vipers (family Viperidae) but the genuses are distinct and the animals are very different (Crotalus in NA; Vipera in EU).

In general, I don't think I understand why phenomena that allow genetically similar species to be extremely geographically distinct - such as land bridges and conjoined continents - have results that appear to be so selective.

submitted by /u/bibliophile785
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Why do levers work? Or in other words, why does work equal force times distance?

Posted: 07 Apr 2019 07:28 AM PDT

Every explanation I find about the principles of levers is that they apply the rule of physics that work equals force times distance. But why does work equal force times distance? What about the distance being greater increase the force that is applied?

submitted by /u/TheOnlyArtifex
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What causes the two big population spikes in China's population pyramid?

Posted: 07 Apr 2019 07:06 AM PDT

China's population pyramid is unique, as it has two large groups of people at the age 25-35 and 45-55. I would guess this has something to do with their one-child policy and their explosive population growth since the 1900s. but i haven't found any sources on this. Could anyone help me out?

submitted by /u/Kulfyr3
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Why do we sneeze?

Posted: 07 Apr 2019 01:09 AM PDT

How do astronauts suits protect them from extreme temperatures in space?

Posted: 07 Apr 2019 12:48 AM PDT

I'm curious to know what those suits are made out of and how they aren't affected by heat, cold, or even radiation when it apperintly can get pretty severe.

submitted by /u/XBlackRookX
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Why are steroids used to treat certain infections?

Posted: 07 Apr 2019 06:41 AM PDT

For example, part of the treatment for acute infective exacerbation of COPD includes 200mg IV hydrocortisone and 30mg oral pred but wouldn't these steroids have immunosuppressive effects - the last thing you want in an infection?

What's the logic behind this?

submitted by /u/Aristo_socrates
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How do volcanoes grow?

Posted: 06 Apr 2019 07:41 PM PDT

As I understand it, volcanoes grow as a result of pressure from magma below and the layering of ash and lava. However, from what I remember from school - this is a slow process. How can it compete with the massive losses associated with eruptions?

submitted by /u/deathkill3000
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Why are there no nuclei consisting exclusively of neutrons?

Posted: 06 Apr 2019 01:53 PM PDT

Why can we arrange colours in a circle?

Posted: 07 Apr 2019 12:22 AM PDT

As far as I understand it, colours are our perception of different wavelengths of light. There is a starting point at a low wavelength and an end at a high wavelength. By that, I have an intuition that there is a 'starting colouring' and an 'ending colour', with a gradient of all other colours inbetween. But yet we are able to arrange colours in a circle! Why is that?

submitted by /u/Galatheon
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How widespread were mental illnesses in the past?

Posted: 07 Apr 2019 03:58 AM PDT

People are always talking about how recently (due to things such as social media, isolation and higher social expectations) there has been a very large spike in mental illness.

But it's not like the past was exactly great either. Thinking back to 50 years ago, in real life bullying was (likely) much more prevalent, racism was everywhere, pretty much all minorities were hated (LGBT, people of colour, women, etc). Among other things.

Looking even further back into medieval times, on top of all the issues mentioned above, conditions were horrible for the vast majority of people, dictators were not at all uncommon, and things just in generally sucked.

So to me, I'd say overall compared to the past, despite technology, things seem like they have really improved in just about all areas. So it's hard for me to believe that mental illness is a lot more prevalent than in the past.

My hypothesis (keep in mind I'm not educated in psychology or history or anything like that) is that people have just been more accepting of people with these conditions and that are methods of detecting (and treating) these issues have improved massively, leading to more people being diagnosed. Not necessarily that there are MORE people with these issues.

So, how widespread were mental illnesses in the past?

submitted by /u/Sol33t303
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Why does bending the ring finger cause the middle finger and pinky finger to involuntarily bend also?

Posted: 06 Apr 2019 11:37 PM PDT

In the context of Astronomy, we often hear that space contains gases and dust. What is space dust and what is it made of?

Posted: 06 Apr 2019 11:24 AM PDT

Saturday, April 6, 2019

How did scientists know the first astronauts’ spacesuits would withstand the pressure differences in space and fully protect the astronauts inside?

How did scientists know the first astronauts’ spacesuits would withstand the pressure differences in space and fully protect the astronauts inside?


How did scientists know the first astronauts’ spacesuits would withstand the pressure differences in space and fully protect the astronauts inside?

Posted: 05 Apr 2019 04:33 PM PDT

What is the base temperature in space?

Posted: 05 Apr 2019 07:47 PM PDT

I've had an interesting thought about what the base temperature of space is. I mean in a spot where no warmth of a star gets through. I thought about 0 Kelvin. But that would be the temperature where everything is cold dead and nothing can move (at least from Earth's perspective). So what would be the base temperature in space?

(I'm sorry if this question is too basic I'm an astro-noob)

submitted by /u/miloscccc
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How do animals with fur and researchers in the arctic get vitamin D?

Posted: 06 Apr 2019 07:01 AM PDT

When viewing macro images of insects they seem extremely clean. Do insects clean themselves thoroughly throughout the day?

Posted: 05 Apr 2019 09:27 PM PDT

Specifically, I've seen a few images of spiders and even the areas around their eyes and mouths appear very clean. How do they reach these areas? Or is there another reason they appear this way?

submitted by /u/ologyism
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When people are listening to loud music through headphones, why do other people only hear the drums/beat of the music?

Posted: 05 Apr 2019 09:22 PM PDT

This happens every day when I'm on the bus, and it just annoys me throughout that 30 minutes of my day. I just thought it was interesting that I only heard the beat of the music, and not the melody.

submitted by /u/Kahoot_Admin5434
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How are there skeletons left over after a volcano eruption buries a town in molten lava? Wouldn't the lava be hot enough to disintegrate bone matter?

Posted: 06 Apr 2019 03:47 AM PDT

Why do smells smell good or bad?

Posted: 06 Apr 2019 02:17 AM PDT

I wasn't sure what flair this belonged under so correct me if I'm wrong.

What is going on in your brain when you smell something good?

Why does it smell good?

What is happening in your brain when you smell something bad?

Why does it smell bad?

Why do some things smell neither good nor bad, They just have a smell?

Do some smells trigger serotonin? Is serotonin what's responsible for making something smell good?

Hell, what is a smell? Is it a molecule, a gas, or a magical fume?

I don't have access to a search engine right now so sorry for any questions that could have been googled.

submitted by /u/crackheadshrek
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Why do excited electrons hesitate to fall back down?

Posted: 06 Apr 2019 05:50 AM PDT

I've read somewhere that when an electron absorps a photon, it is excited to a higher energy state, where it remains for a few femtoseconds, whereafter it "decays" back down to a lower energy level, emitting a photon. Why doesn't the electron decay immediately, and what determines how long it stays excited?

submitted by /u/oz1sej
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How does a nerve gas mask differ from other gas mask?

Posted: 06 Apr 2019 05:40 AM PDT

WWI mask were tested against chlorine , phosgene and mustard gas. What would be the necessary modifications to be effective against nerve gases, such as tabun and sarin?

submitted by /u/groenewald
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Are there any animals who are known to travel somewhere to die?

Posted: 05 Apr 2019 07:29 PM PDT

I'm currently watching Our Planet on Netflix and there is a part where they film baby flamingos. I started thinking "That is a lot of babies. Do an equal amount of adult birds die each year? If yes, that seems like a large amount of dead birds in one area". I imagined lots of them dying and then thought about whether or not animals travel to die.

submitted by /u/CodyLeeTheTree
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Are the products of burning tobacco especially toxic comparably?

Posted: 06 Apr 2019 07:44 AM PDT

As a layman I think to know that many plants have the same general 'structure' (on a certain level), which should lead to many plants having similar reaction products when burnt.

Does tobacco contain distinct 'own' compounds that make it's smoke especially toxic to humans, ie more toxic than the smoke of comparable plant matter?

submitted by /u/Ebenberg
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Do animals know when to stop eating or eat less since their prey can't reproduce quick enough?

Posted: 06 Apr 2019 07:42 AM PDT

We have a lot of trouble with overfishing the ocean for example. so I asked myself If animals may have such a problem as well and stop before it's too late.

submitted by /u/Dogtransformer
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What damage do amphetamines (including the controlled substance methamphetamine) do to the body, what causes death in user/abuser and how long does such person live since beginning of abuse?

Posted: 06 Apr 2019 12:59 AM PDT

I know there is not one type of amphetamine and I am interested in all of them (including methamphetamine).

I would also like to ask that if a non ADHD person would take Ritalin/Adderall what would he feel? Would he feel euphoria and get instantly addicted?

submitted by /u/GullibleHospital
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What type of iron oxide forms on the surface of steel parts during tempering?

Posted: 05 Apr 2019 08:06 PM PDT

When steel is tempered, depending on the temperature and atmosphere, the parts will form a different color ranging from light brown to lue to black. Is this Fe2O3 or Fe3O4 (magnetite).

What range of temperatures is Fe3O4 formed on iron/steel?

submitted by /u/ReptilianOver1ord
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Do animals recognize their own “voices” (barks, meows, growls, etc.) when they hear them on recordings?

Posted: 05 Apr 2019 02:37 PM PDT

How different is the human species compared to what it used to be like 9000 years ago?

Posted: 06 Apr 2019 03:21 AM PDT

Can I electroplate with 925 silver? Or does the anode have to be 999 silver?

Posted: 06 Apr 2019 03:15 AM PDT

I wanted to give silver electro plating a try tomorrow for fun and just plate an old penny. I have a bit of silver from metal detecting which is mostly 925 silver, can I plate with this? Or does the anode HAVE to be pure 999 silver?

Cheers

submitted by /u/TTT334
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Why have teen birth rates declined sharply across every state in the US over the past 30 years?

Posted: 05 Apr 2019 11:02 PM PDT

Before looking at the data myself, I wouldn't have guessed that teen birth rates have declined dramatically in *every* US state since 1990. What explains this country-wide decline?

Here are two charts showing the decline in teen birth rates:

Time series of teen birth rates in every US state between 1990 and 2016.

Time series of teen birth rates in the US, disaggregated by race (2007-2017).

submitted by /u/inspurious_
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Were the effects of being exposed to a vacuum ever explored scientifically by putting animals in a vacuum chamber?

Posted: 06 Apr 2019 01:56 AM PDT

Very long time ago when nobody really cared about the well-being of animals somebody told me that mice were put in a vacuum and that made them inflate like balloons and killed them. This question came to me when reading a post about the testing of pressure suits for astronauts.

submitted by /u/public_image_ltd
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Friday, April 5, 2019

Does launching projectiles significantly alter the orbit of Hayabusa2?

Does launching projectiles significantly alter the orbit of Hayabusa2?


Does launching projectiles significantly alter the orbit of Hayabusa2?

Posted: 05 Apr 2019 06:52 AM PDT

I saw the news today that the Hayabusa2 spacecraft launched a second copper "cannonball" at the Ryugu asteroid. What kind of impact does this have on its ability to orbit the asteroid? The 2kg impactor was launched at 2km/s, this seems like it would produce a significant amount of thrust which would push the spacecraft away from the asteroid. So what do they do in response to this? Do they plan for the orbit to change after the launch and live with it? Is there some kind of "retro rocket" to apply a counter thrust to compensate for it? Or is the actual thrust produced by the launch just not actually significant? Here is the article I saw: https://www.cnet.com/news/japan-is-about-to-bomb-an-asteroid-and-you-can-watch-here/

submitted by /u/showponies
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[Astronomy] Do giant, highly oblate planets exist?

Posted: 05 Apr 2019 06:51 AM PDT

I'm reading one of the first hard science fiction novels written: Mission of Gravity by Hal Clement. In it a world called Mesklin is described with, among others, the following characteristics:

  • supergiant,
  • highly oblate,
  • strong gravity (a gee force gradient, starting at 3 g on the equator, and ending at 665 g on the planet's poles).

I'm very curious if this falls in the technically possible category or if we have actually found a planet that has the rough characteristics as described.

submitted by /u/nevahre
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Why can excited monoatomic gases (eg neon) emit photons but not homonuclear molecules (eg dinitrogen)?

Posted: 05 Apr 2019 07:00 AM PDT

this is from the wikipedia page https://en.wikipedia.org/wiki/Carbon_dioxide_laser

From the article: electron impact excites vibrational motion of the nitrogen. Because nitrogen is a homonuclear molecule, it cannot lose this energy by photon emission, and its excited vibrational levels are therefore metastable and relatively long-lived.

submitted by /u/nicktohzyu
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Why are testicles considered a gland and ovaries are organs? Or what is the difference between a gland and an organ?

Posted: 05 Apr 2019 04:19 AM PDT

Are there any herd animals that exhibit sacrificial behaviour when being hunted by predators?

Posted: 05 Apr 2019 03:26 AM PDT

Have there been any cases where the old/weak/infirm members of the herd have sacrificed themselves to predators to allow the greater herd and younger animals to escape?

submitted by /u/DubstepBurrito
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Do people native to high altitude places experience any negative effects on their health when at sea level?

Posted: 05 Apr 2019 01:17 AM PDT

Those huge cargo ships and oil tankers have a really small anchor compared to the overall size of the ship. How does such a small anchor manage to keep the ship in place?

Posted: 05 Apr 2019 04:44 AM PDT

Is the light from the sun mostly incandescence or a byproduct of fusion?

Posted: 04 Apr 2019 03:36 PM PDT

I imagine it's a combination, but are we mostly seeing radiant energy cast off from fusion, or the incandescent glow of the hot matter afterwards?

submitted by /u/oliksandr
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How do we tell the difference between convergent, divergent, and parallel evolution?

Posted: 05 Apr 2019 05:20 AM PDT

Because for the most part, all we get to see is a snapshot in the chain, how can we tell if species are related or not?

submitted by /u/Ozurip
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What is the effect of resellers on the economy?

Posted: 04 Apr 2019 06:05 PM PDT

I'm not refering to retailers per se, because I can understand the effect they play: grouping the products in a physical location.

These resellers end up raising the prices of a product that wouldn't cost that much otherwise. I'm not talking about speculating that a product will become valuable at a later date, I'm talking about products in established markets (proven to be stable, people have been buying it for years) being bought at a lower price and then resold for a small profit.

What would happen to an economy where these people didn't exist? Would prices keep going down if the demand was low? Because these people create a fake demand for the products.

Is there more I can read about this subject?

submitted by /u/pphp
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If you shoot a gun while on a space walk, would the bullet be able to escape the solar system?

Posted: 04 Apr 2019 04:02 PM PDT

How has the widespread use of penicillin as an antibiotic affected the Penicillium fungi in the wild? Has the fungi become any more vulnerable to bacterial infection due to penicillin-resistant bacteria as a result of its use?

Posted: 04 Apr 2019 10:08 PM PDT

Is it possible for two embryos with different fathers to fuse and create a human chimera?

Posted: 04 Apr 2019 10:29 AM PDT

If superfetation occurred with each embryo having a different father, could the death and absorption of one result in the creation of a human chimera with two different fathers? Would the product even be viable?

submitted by /u/neptunesbane
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Do tidal forces from the Moon have any effect on the Earth's mantle?

Posted: 04 Apr 2019 10:07 PM PDT

Relationship, even an equation between prevalence of atoms/molecules and stability?

Posted: 04 Apr 2019 07:55 PM PDT

This may seem an elementary relationship, but is there an equation out there, like a conversion function that takes some index value that represents an atom or molecules prevalence in the universe and outputs the relative stability of that atom or molecule? And vice versa?

I couldn't find anything on google about it. Apparently there is a weak relationship between nuclear binding energy and the as you go up the periodic table from hydrogen. I don't think that's relevant, but it would make intuitive sense if the more stable an element or molecule (like H20 or Helium gas) are generally more prevalent in the universe than less stable ones...and if so, is there some sort of equation devised to easily calculate one to get the other? Is it in the Handbook of Chemistry or something like that?

submitted by /u/ilumrf1986
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Second mode waves in boundary layers and instability?

Posted: 04 Apr 2019 06:42 PM PDT

Can anyone explain what second mode waves are in terms of fluid mechanics and what boundary layer instability means?

submitted by /u/nasawesome
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When drinking water, do Hydronium and Hydroxide ions serve different purposes when absorbed by the body?

Posted: 04 Apr 2019 09:19 PM PDT

How do we know that the four legged whale that was just announced to be have been found in Peru should be classified as a Whale?

Posted: 04 Apr 2019 08:22 PM PDT

I would assume it has some to do with similar bone structures and stuff but I was hoping to learn some specifics as to how we know this should be classified as an earlier version of whales and not some other creature. Is there a way to tell just based off of bone structure that it should be classified as a mammal? I would think that's an important early step. Thank you!

submitted by /u/jobletofscience
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Could someone help me with Constant speed of light and all that?

Posted: 05 Apr 2019 01:16 AM PDT

I don't get time dilation, lenght contraction and the constant speed of light, so I hope someone can help me out.

First off, instead of lenght contraction, time dilation and the constant speed of light, why can't I say that light slows down when I approach it and accelerate when i move away from it? To me it seems like I would get the same results ether way. I would measure the speed of light as c no matter how fast I'm moving or in which direction. What law am i violating?

So to a little tought experiment. I stand between two laserpistols. when I press a button a signal goes to both lasers and they fire when they recieve it. Will the two lasers reach me at the same time if I move towards either pistol? If not, then what is so special about light?

If the signal sent two footballs towards me, the ball I moved towards would be the first to reach me because:

  1. the speed of the ball I am moving away from (ball A) would decrease relative to me and vice versa for ball B.
  2. the distance ball A has to move to reach me increases, and vice versa for ball B.

So how does light solve this? (Given that light really do hit me at the same moment no matter my movement and given my "light speeds up and down according to my motion"-statement is wrong).

submitted by /u/Kingchachacha
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What is the depositional environment for a low permeability carbonate reservoir?

Posted: 04 Apr 2019 09:20 PM PDT

I'm currently working on a design project that has a low permeability carbonate reservoir with a 21% porosity. So far I've been reading papers but not understanding what is happening with the geology. Any geologists have an explanation? For context, the reservoir I am studying is located in the Ratcliffe beds of the Oungre evaporite (Midale evaporite).

submitted by /u/andarott
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Why are depleted uranium penetrators "self sharpening"?

Posted: 04 Apr 2019 10:46 AM PDT

I keep hearing that depleted uranium is "self sharpening" and the best explanation I've found is that DU burns away on the edges. While I don't doubt this is true, it still doesn't explain what exactly it is about DU that causes it to happen instead of having the nose rounded over.

(and yes I already know about post-pen effects so you don't need to explain that)

submitted by /u/TheDapperDugong
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Adding water to paint makes it flow better and lay more flat initially. Does adding water make the paint dry more quickly?

Posted: 04 Apr 2019 09:03 PM PDT