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Friday, June 8, 2018

When undersea mammals are born, is it a rave for them to surface to breathe?

When undersea mammals are born, is it a rave for them to surface to breathe?


When undersea mammals are born, is it a rave for them to surface to breathe?

Posted: 07 Jun 2018 11:52 PM PDT

I'm in the shower and wondering if dolphins and whales are born deep enough under water they will suffocate from lack of oxygen.

EDIT: Race, not rave. Don't think things get that crazy for fish. Mobile won't let me update the title. Sorry.

submitted by /u/A-E-I-O-U_sometimesY
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Do any animals spit? And if there are none, why?

Posted: 08 Jun 2018 07:18 AM PDT

EDIT: It would seem I forgot that llamas existed so I have another question. WHY do some animals spit and others don't?

submitted by /u/TurnedUpbeat
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Is there a limit for how many frames-per-second we can capture or display with cameras or screens?

Posted: 07 Jun 2018 09:29 PM PDT

How do satellites fall out of orbit?

Posted: 08 Jun 2018 05:51 AM PDT

I've heard of satellites that fall to Earth, and I've wondered how that happens.

submitted by /u/Viking_Chicken
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When physicists say light has a wave length of, say 400 nm, what do they actually mean?

Posted: 07 Jun 2018 10:01 PM PDT

Like what is actually fluctuating across those 400 nm? Is the photon moving up and down through space (ie it's moving in a wavy manner)? Is it causing space to expand/contract (like a sound wave pushes air molecules together/apart)? Is it some attribute of the photon that changes over that distance (brightness or energy levels or something)? This is just one of those bits of physics that seems pretty crucial but that I just can't find a good explanation for.

submitted by /u/Andrewcshore315
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Do rainbows make complete circles but we just don’t see them? Or is it just part of a circle?

Posted: 07 Jun 2018 05:06 PM PDT

Faith Rodgers recently accused R. Kelly of knowingly infecting her with herpes. Is there a way to prove *he* infected her, based on blood (or other) tests?

Posted: 07 Jun 2018 09:07 PM PDT

Assuming you could test both parties, and both were infected; would it be possible to compare the virus from party a to the virus from party b and say one infected the other? Could you show direction of transmission (using number of mutations, maybe)?

submitted by /u/Denniosmoore
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why don't companies like intel or amd just make their CPUs bigger with more nodes?

Posted: 08 Jun 2018 07:30 AM PDT

In an open-channel flow, if the flow is supercritical and it meets a contraction in the channel, why does the water depth increases?

Posted: 08 Jun 2018 05:17 AM PDT

I mean, shouldn't it decrease as the width of the channel is narrower and therefore the flow will accelerates, increasing its speed, to keep the flow continuous?

Does this mean that flow has gained energy?

submitted by /u/GrandMagusSPR
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Aren't all elements radioactive nuclides to some extent?

Posted: 07 Jun 2018 06:35 PM PDT

Sorry if my question is really stupid!

submitted by /u/Nachi445
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In an open primary election, is it better to vote for my preferred candidate from Party A or the 'least evil' from opposition Party B?

Posted: 07 Jun 2018 06:00 PM PDT

This is a bit multi-diciplanary. Game Theory? Ask Math?

submitted by /u/jboeke
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How can smart scales using bioelectrical impedance differentiate water from muscle/fat?

Posted: 08 Jun 2018 02:51 AM PDT

Since muscle and fat are themselves composed of water too.

submitted by /u/daiqo
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Can someone describe - at the physical level - how sound waves propagate through air?

Posted: 08 Jun 2018 02:49 AM PDT

My knowledge of physics stopped at secondary school (= high school for US readers) 30 years ago. I've always been interested in music and I'm currently reading a book about acoustics. While reading that book it occurred to me that although I take the propagation of sound through air as given I struggle with forming a mental model about how this works at a molecular level.

So far what I have is something like ...

The molecules in the speaker cone move forward. These molecules push against the molecules in the air immediately in front of the speaker cone moving them forward. As these air molecules move forward they push against the air molecules in front of them. So I get how a compression wave might be generated.

But then the molecules in the speaker cone move backwards. So ... how do the molecules in front of the speaker know to move backward? I get that it's an area of low pressure but that just means "fewer molecules" right? So do the molecules in front of the speaker - have they just rebounded off other air molecules or ... you can see I'm getting in a muddle. Is any of this to do with anything bumping into anything or is this all just nonsense?

submitted by /u/HashPram
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Why does paper turn yellow after some time?

Posted: 08 Jun 2018 02:32 AM PDT

Today I came back from a trip and I noticed that a sheet of paper that I left on my PC last week has a yellow, moisty stain. I doubt that it's just dirty, especialy since we all heard a saying about yellow paper, so I wonder if it's a chemical reaction of cellulose and oxygen. Also, does ink have any effect on it? Why is it, that when we buy new printer paper it's fresh white and stays that way for a long time?

submitted by /u/Gadongbadabong
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What do you call the point where a particle breaks apart?

Posted: 07 Jun 2018 04:46 PM PDT

I'm a senior high school student, so a more simplistic explanation if possible would be much appreciated! My chem professor has informed me that compounds can have triple points as long as they do not exceed 'the point where a particle falls apart'. When asked what it falls apart into, I was told 'some kind of gaseous plasma.' I'd assume there would have to be a ridiculously high amount of pressure and an impossibly hot temperature for this to happen.

What does this actually mean? Is somebody able to explain this using an example of a simple compound?

Thank you very much!

submitted by /u/MedicMoth
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Can you have a c-shaped copper coil with a magnet on a arm travel through the gap in the circle and still generate electricity?

Posted: 07 Jun 2018 02:41 PM PDT

Newb here.

Trying to understand if electricity can be produced if the copper coil isn't a closed circle.

Any examples would be welcome :)

Thanks in advance!

submitted by /u/DB-JR
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Why are negative integer factorials like (-3)! undefined while rational numbers like (-3,5)! are?

Posted: 07 Jun 2018 09:30 AM PDT

Can someone derive the intermediate axis theorem?

Posted: 07 Jun 2018 03:17 PM PDT

Hello everyone, I am a future senior in high school and I just finished AP Physics 1. I came across an interesting phenomenon called the intermediate axis theorem. I understand what the intermediate axis theorem is and how it works. However, to me at the moment I see it as a rule without any understanding of it. I do not understand why the intermediate axis does not have the same restoring force that the other two axes have. If someone could maybe derive the theorem and explain it along the way that would be great. I have found this post: https://www.reddit.com/r/askscience/comments/3lf6x8/why_cant_you_spin_a_phone_around_each_axis/cv5scxb/?st=ithibtpr&sh=d1ec8e9f already and the problem is that I am not completely familiar with all of the terms and language they use. Please keep in mind that even though I love physics I am still only in ap physics 1 when you are answering this question.

submitted by /u/toomysxs
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Have all bosons in a Bose Einstein condensate the same phase?

Posted: 07 Jun 2018 11:22 AM PDT

The bosons in a Bose Einstein condensate form a "macroscopic coherent wavefunction". But can the bosons interfere with each other? Or is this question senseless in some sense?

submitted by /u/MaoGo
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Thursday, June 7, 2018

Why does a compressed natural gas tank have expiry date on it? Does it mean it's no longer safe to use after the expiry date?

Why does a compressed natural gas tank have expiry date on it? Does it mean it's no longer safe to use after the expiry date?


Why does a compressed natural gas tank have expiry date on it? Does it mean it's no longer safe to use after the expiry date?

Posted: 06 Jun 2018 11:07 PM PDT

I live in a country where I could use compressed natural gas (CNG) as my vehicle fuel instead of petroleum. So I have a CNG tank installed in my boot 9 years ago.

The CNG tank's expiry date is reaching soon, I should definitely go for inspection, but does the expiry date means anything at all?

I already Google the question, but the top results don't really provide any information about what happens when the CNG tank "expired".

submitted by /u/SleepingAran
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How/why does the body “get used to” cold or hot objects after being in contact for a while?

Posted: 06 Jun 2018 09:22 PM PDT

Is it that the body moves the temperature to the bodies temperature? Or does that body actually get used to it? Is it the skin touching the object 'numbing', or is it a mental change? Thanks!

submitted by /u/mapdumbo
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Chemically, why was the Fat Man more powerful than the Little Boy? (The nuclear bombs dropped on Hiroshima and Nagasaki)

Posted: 07 Jun 2018 08:09 AM PDT

Does a rainclouds movement and velocity affect its rainfall?

Posted: 07 Jun 2018 06:02 AM PDT

Where any black holes created immediately after the Big Bang?

Posted: 06 Jun 2018 09:43 PM PDT

Edit subject: "Were" - not "Where"... Could it be possible all of the supermassive black holes at the center of today's galaxies are remnants of the Big Bang? Also could it be possible that there was not a single point in the cosmos that started it all but instead each supermassive black hole played a part in the inflation of the universe? Is it possible all of the supermassive black holes in the early Universe were able to eat the inflation of matter and space but the big bang in fact was the turning point where all of these supermassive black holes could no longer consume SpaceTime fast enough?

submitted by /u/burner70
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Why does our immune system not detect and fight off the bodies own cancer?

Posted: 06 Jun 2018 10:42 PM PDT

How come there are no accurate computer models of wetlands?

Posted: 07 Jun 2018 05:19 AM PDT

We have good models for weather, crops, e.t.c. it just seems to me that science is lacking, especially for an ecosystem that provides many benefits.

submitted by /u/Kickstand8604
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If copper has the best thermal conductivity, why are some computer coolers made out of copper and aluminium, and not just copper?

Posted: 07 Jun 2018 08:35 AM PDT

What is heat?

Posted: 07 Jun 2018 08:21 AM PDT

Is there coulomb repulsion between neutrons within a nucleus?

Posted: 07 Jun 2018 07:15 AM PDT

Neutrons are of course electrically neutral. But since neutrons are constituted of 2 Down and 1 Up quark, both having fractional electric charges, is there any coulomb interaction between two neutrons that are very close to each other (like in a nucleus)? I would imagine that there should be something like charge displacement within the neutrons due to the presence of the charged quarks of the other nuclei (induced eletrical dipole like with Van-der-Waals interaction). On the other hand I'm pretty sure the strong interaction in this regime is so much stronger that this coulomb interaction is neglectable.

Are the charges of the quarks even meaningfully localized within the neutron or is it like a homogeneous state where there's not even the possibility of having a charge displacement?

submitted by /u/Ernst37
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How do contact lenses automatically slide to your iris/pupil?

Posted: 06 Jun 2018 07:25 PM PDT

Are we sweating while swimming?

Posted: 06 Jun 2018 03:57 PM PDT

Or does the body get cooled enough from the water, so that we don't have to sweat?

submitted by /u/zlft
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Do nuclear weapons expire?

Posted: 06 Jun 2018 10:08 PM PDT

I would certainly hope so, considering there's really no ethical way of disposing them.

submitted by /u/Chenaniganz
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How were special relativity and quantum mechanics conflicting before quantum field theory, and what does QFT do to resolve them?

Posted: 06 Jun 2018 10:20 PM PDT

How does the human body react to tattoos?

Posted: 06 Jun 2018 05:35 PM PDT

I mean, i know that tattoos are made with some sort of incision and the ink is sort of injected into a layer of the skin, but why doesnt the body fight the ink with antibodies or something, and if it does, why doesnt the body erase the ink or at least reject it?

submitted by /u/DrOpe99
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Physicists or physical chemists: what is a surface plasmon?

Posted: 06 Jun 2018 08:26 PM PDT

An undergrad researcher here doing work with gold nanoparticles. In solution they are a dark red color, with the hue depending on the diameter of the spheres. The only explanation I have found so far is "surface plasmon resonance" saying that a plasmon is a collective oscillation of the electron sea - what does this mean and how does it correlate to the surface of the sphere and the color of solution?

submitted by /u/hilinia
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Why is download speed faster than upload speed?

Posted: 06 Jun 2018 06:07 PM PDT

I recently did a speed test for my internet, and I was wondering why there is such a large difference between upload speeds and download speeds.

submitted by /u/tubazz
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How does scratching the skin remove the itchy feeling?

Posted: 06 Jun 2018 05:28 PM PDT

Why do we even feel the need to itch?

submitted by /u/wgroenning
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How do you contain tokamak energy when it is hotter than the sun?

Posted: 07 Jun 2018 03:02 AM PDT

So recently a fusion reactor achieved temperature hotter than the sun. How do you contain this without it melting everything around it?

I understand magnetism has something to do with it, which makes sense because nothing is touching but doesn't heat still radiate outwards? Or does the magnetism prevent the radiation spreading which means you can stand next to something millions of degrees and not feel the heat?

submitted by /u/ScepticalProphet
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Can a superfluid be compressed?

Posted: 06 Jun 2018 05:48 PM PDT

Why does Enceladus have geysers made of water and ice spewing from its surface whereas Europa does not? Is there any known reason which explains this notable discrepancy between these two moons?

Posted: 06 Jun 2018 10:12 AM PDT

Both moons are believed to have their own global oceans underneath their icy crusts and scientists reckon that these oceans exist due to gravitational tugging from their parent planets. Why does one of these two moons have jets of water and ice while the other one does not?

submitted by /u/Will_Hack_4_Food
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Do gas giants really have a surface?

Posted: 07 Jun 2018 02:17 AM PDT

Wednesday, June 6, 2018

Why do things get darker when wet?

Why do things get darker when wet?


Why do things get darker when wet?

Posted: 05 Jun 2018 02:05 PM PDT

What happened to acid rain? I remember hearing lots about it in the early 90s but nothing since.

Posted: 06 Jun 2018 04:56 AM PDT

Does dust affect space telescopes such as Hubble?

Posted: 06 Jun 2018 05:19 AM PDT

There must be a huge amount of isolated dust particles in Space, particularly around Earth's atmosphere. I was wondering if dust gets stuck to Hubble's (and other telescopes') lenses or even damages the lenses due to the velocity it travels at? How do Space agencies deal with this issue?

submitted by /u/WonderfulMud7
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Why isint Rubidium more conductive than Copper?

Posted: 06 Jun 2018 04:14 AM PDT

Title. They both form a 1+ ion (mainly) but Rubidium has less attraction towards it's outer electron than copper, because of electron shielding and atomic radius, suggesting that it's valence electrons should be more mobile than copper, hence Rubidium should be more conductive. This however is not the case - why not?

submitted by /u/InProx
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Companies making washing detergent have been launching new and improved products for years. So what's the difference between a detergent sold in 1978 and one on sale today?

Posted: 06 Jun 2018 03:58 AM PDT

If each neutrino flavor has a different mass and this phase shifts their wave packet as they move causing oscillation, why isn't the wave packet stretched over long distances?

Posted: 06 Jun 2018 06:34 AM PDT

I'm trying to understand how neutrinos oscillate and I read that because each flavor has a different mass (the sum of all 3 is less than 1 millionth of an electron's mass) this causes their wave packet to phase shift but wouldn't this stretch out the wave packet over long distances so when the neutrino is in its heaviest form it would slow down? I guess mass can't change so how does this work?

They found a 4th neutrino that's apparently heavier and sterile which is what got me thinking about this: https://science.slashdot.org/story/18/06/05/2036233/scientists-may-have-discovered-a-new-fundamental-particle-sterile-neutrino

submitted by /u/redditor100k
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Can you get muscle cancer?

Posted: 06 Jun 2018 05:45 AM PDT

I heard cancers from everywhere from testicles to brain, but i have never once heard of muscle cancer.
Can you have cancer in your biceps for example?

submitted by /u/Baji25
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How do our bodies know when to wake up? What stops us from sleeping forever?

Posted: 05 Jun 2018 01:43 PM PDT

Does the general theory of relativity predict that the universe is expanding?

Posted: 06 Jun 2018 01:08 AM PDT

Have their been any more gravitational wave detections?

Posted: 05 Jun 2018 09:10 PM PDT

Can you catalyze the aluminum - gallium - water reaction?

Posted: 05 Jun 2018 12:18 PM PDT

I've read that the reaction is good at producing hydrogen, yet the limiting factor is that it produces it very slowly. Does anyone know of any research done into accelerating this reaction?

submitted by /u/Rideron150
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What's the difference between the South and North pole of a magnet?

Posted: 05 Jun 2018 10:04 AM PDT

An expirmental physicist is magically teleported to another planet. The physicist has access to any instrument or piece of equipment they desire EXCEPT a magnet or compass from Earth (and its magnetic field) with the poles labeled "North" and "South." How could they tell which pole of a magnet is which?

submitted by /u/SingularityIsNigh
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Why is SHA256 not a good hash for passwords?

Posted: 05 Jun 2018 10:19 AM PDT

I've read that for password hashing, hash functions such as Bcrypt or PBKDF2 are preferable because they are much slower to calculate. SHA256 was not good because it was very fast to compute. However, just as people recommended to have multiple iterations of hashing for Bcrypt, couldn't I have multiple iterations of SHA256 hashing for each password? What makes a SHA256 password hashed 1 million times iteratively worse than a Bcrypt password hashed 1000 times?

submitted by /u/Dueling7
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How does a device keep it’s hostname?

Posted: 05 Jun 2018 08:25 AM PDT

When a device with a hostname is disconnected and reconnected to a network, how is it reassigned the hostname given by the network?

submitted by /u/Worgencyborg
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Why are Rivers Uneven and as a Result Turbulent?

Posted: 05 Jun 2018 12:46 PM PDT

I am currently studying lithosphere, hydrosphere and physical geography topics and understand erosional and depositional features along with differential erosion. We do not study rivers as much as I thought we would. As a result I have a few questions which extend from my first:

Why are not all river beds flat? Where I live the rivers have ledges of the same rock which I assume is what causes turbulence and localised white water- what causes the rock to be deformed like this? Is it correct to assume that this is how turbulence solely arises?

I do know some rivers are flat and merely run along the path of least resistance.

Any further reading or recommendations to textbooks would be appreciated.

submitted by /u/MythicalGeology
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