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Tuesday, November 29, 2016

How do blue whales sleep?

How do blue whales sleep?


How do blue whales sleep?

Posted: 28 Nov 2016 03:28 PM PST

The wikipedia article didn't say and google results were inconclusive.

Thanks!

submitted by /u/csrabbit
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Could the 2D geometry of quantum dots allow for easier or higher-temperature superconductors?

Posted: 29 Nov 2016 06:57 AM PST

I'm giving my students a quiz today and just had a musing about this. Quantum dots are 2D pseudo-atoms, per my understanding, which have unique and different electron orbitals due to the 2D nature of the Q.dot.

I thought I would ask more learned heads than my own.

submitted by /u/ARSciGuy
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Why did these leaves near the street lamp turn red earlier than the rest?

Posted: 28 Nov 2016 11:45 PM PST

I posted this photo to /r/mildlyinteresting yesterday, nobody there seem to have a definite explanation so far.

Does anybody know why these leaves that are closer to a street lamp turned red earlier than the rest?

submitted by /u/ozgurakgun
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Why do desktop fans look more like boat propellers than aircraft propellers?

Posted: 28 Nov 2016 08:09 PM PST

Is deriving symetric?

Posted: 29 Nov 2016 07:25 AM PST

Usually derivation is explained like how the function changed when the variable changed. The way we do it is comparing the current point with a close previous one. (f(x)-f(x-h))/h with small h My question here is, can we compare the current point with the close next one? Like doing a mirror at x (f(x+h)-f(x))/h with small h I did a few tries with simple functions and it's working and makes sense but I don't know if it's something general or not.

submitted by /u/Juanda1995
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How is it possible for galaxies at the edge of the universe to travel faster than the speed of light?

Posted: 28 Nov 2016 10:33 PM PST

I watched recently a video on how dark energy makes it possible for galaxies to move faster than the speed of light. I still don't understand how though because I've always thought the speed cap for any object is the speed of light!

submitted by /u/moistenoki
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Long after a major meteorite impact, does seismic activity around the crater increase or decrease?

Posted: 28 Nov 2016 04:57 PM PST

For example, after the KT extinction impact. Does such an impact force a release of seismic stress? Cause more stress? Have no effect?

submitted by /u/cantgetno197
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What would the night sky be like on a planet near to the core of the galaxy?

Posted: 28 Nov 2016 12:16 PM PST

Since the density of stars grows as we approach the center of the milky way, I wonder if the night sky on a planet similar to ours would be brighter than it is here.

submitted by /u/Slymass
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Are there any real photos of Black Holes, or are all "pictures" simply artist renditions?

Posted: 28 Nov 2016 12:26 PM PST

I cant seem to figure out if there are any real pictures of a Black Hole. I was thinking that becasue no light can escape it, and all light that touches it enters it, would it even be posible for us to see a black hole, or would we just see everything around it and infer that their must be a black hole there?

submitted by /u/AmericanMeat
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Why do some minerals crystallize into cubes while others form hexagons?

Posted: 28 Nov 2016 08:01 PM PST

first derivative of a curve equal to 0 indicates a minimum or maximum point. Second derivative equal to zero indicates a point of inflection. Does the third derivative being zero mean something as well?

Posted: 28 Nov 2016 02:54 PM PST

Does general relativity really affect GPS?

Posted: 28 Nov 2016 03:32 PM PST

Various (seemingly reliable) sources on the internet seem to suggest that GPS must account for time dilation due to the Earth's gravitational field. It seems to me, however, that since all of the satellites are at about the same altitude, we should expect this time dilation to affect all of them equally and thus have no effect on the position determined by the receiver.

What am I missing?

submitted by /u/throwawayForGR
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Does acceleration decrease as velocity increases??

Posted: 28 Nov 2016 04:34 PM PST

So everyone knows that achieving the speed of light is impossible. So say for instance you were on a spacecraft at a velocity just below the speed of light, and you continued to have the same amount of thrust as in speeds prior. What would happen to your acceleration? Would you not be able to accelerate to or past the speed of light? That being said, would the same principle apply for velocity in general? As your velocity increases your acceleration decreases? Would, with the same amount of thrust, your acceleration differ from flying through space at 3,000 mph and flying through space at 100,000 mph. I'm sure there's a sturdy explanation to this but I just thought about this today and thought I should share. Also, hope I've explained my mind well enough.

Thank you for your time, Caleb

submitted by /u/Calebkeller2
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[Physics] What are the maths behind the wavefunction psi?

Posted: 28 Nov 2016 08:18 PM PST

Hi, we had the wave/particle duality for electrons in the lecture today and described the different orbitals with it. Furthermore we spoke about the mathematical/theoretical concept behind it briely. But now im asking myself what the wavefunction is!

submitted by /u/Tirunculus
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Why is e-e+ -> μ-μ+ such an important reaction?

Posted: 28 Nov 2016 10:23 AM PST

It's the first example of "real" process worked out in Peskin and Schroeder, and they mention that it's used as a calibration for detectors. Can anyone tell me about this? Specifically, I'd naively expect e- e+ -> e- e+ to be easier to observe, because the right-hand mass is lower.

It's possible I could answer the question by computing the cross-section myself, or reading more, but I'm a mathematician and don't know anything about experiments so I'd probably get it wrong.

submitted by /u/Homomorphism
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[Physics] In a hypothetical empty universe, a single hydrogen atom pops into existence. Will that atom remain as an atom forever?

Posted: 28 Nov 2016 03:13 AM PST

If not, what will be the first thing that makes the hydrogen atom no longer an atom? Some bizarre quantum stuffs?

submitted by /u/StupidPencil
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Why are Sierpinski numbers important and what are they used for?

Posted: 28 Nov 2016 04:47 AM PST

related news: "At more than 9 million digits long, the new prime number is the seventh largest prime ever found, and it just cut the six possible candidates for the elusive Sierpinski number down to five."

Why are Sierpinski numbers important and what are they used for?

submitted by /u/rebootko
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Why are there no volcanoes or trenches at the bottom of the ring of fire?

Posted: 28 Nov 2016 12:30 PM PST

Like this. My friend suggested that it is because they are close to the poles, but she thought that also might not be the case because there are volcanoes very far north.

submitted by /u/the_panda0704
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Why did it take longer to find the Higgs than the top quark?

Posted: 28 Nov 2016 07:26 AM PST

So as best we can tell, the top quark is about 35-40% heavier than the Higgs and decays in a few hundredths of the time. Why were we able to confirm the top so much earlier and at much less energy than needed for the Higgs?

submitted by /u/bigscience87
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Monday, November 28, 2016

What led Max Planck to assume energy levels are quantized?

What led Max Planck to assume energy levels are quantized?


What led Max Planck to assume energy levels are quantized?

Posted: 27 Nov 2016 03:24 PM PST

What causes the randomness of internet speeds, even on Ethernet?

Posted: 28 Nov 2016 06:00 AM PST

Is acquiring a taste for something like black coffee a physical change, a psychological change, or a combination of both?

Posted: 27 Nov 2016 02:02 PM PST

Why aren't we seeing organic photovoltaics solar cells everywhere? What's the catch?

Posted: 28 Nov 2016 06:48 AM PST

What prevents individual cell phone radios from "stepping on" each other's transmissions?

Posted: 28 Nov 2016 05:15 AM PST

I understand how channel hopping works in wifi and other basic radio technologies, but it seems like deconflicting the transmissions of cell phones in a busy city would pose a problem of a much greater magnitude. How do they do it?

submitted by /u/AirRoboted
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Why do we need a Higgs Boson for the electroweak force?

Posted: 28 Nov 2016 05:13 AM PST

I've read about the Higgs field, and seen that it was needed to make the weak forces behave in the way we observe. What I do not get is why can't the W and Z bosons just have mass themselves? What problems would arise if the W and Z bosons themselves had mass?

submitted by /u/Sulfafnir
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Do animals consumed whole by predators (such as snakes) go through rigor mortis? If so, how does this affect digestion and the predator's movement, especially for larger prey?

Posted: 27 Nov 2016 06:54 PM PST

Clouds. What determines the point when clouds are too saturated and start to rain, and what controls the intensity at which rain falls over time?

Posted: 27 Nov 2016 02:38 PM PST

Read the Title

submitted by /u/tubob
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How is this cardboard guitar able to withstand the 200+ lbs of tension applied by the strings?

Posted: 27 Nov 2016 08:26 PM PST

If gravity "moves" at the speed of light and is "emitted" in waves, why does it pull and not push?

Posted: 28 Nov 2016 02:46 AM PST

Sorry, if this is a stupid question.

submitted by /u/Fr4t
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Why do some fruits grow in 'slices'?

Posted: 27 Nov 2016 02:31 PM PST

For example, the clementine or the orange, they come in slices that each have a sort of skin separating them from other slices. Why do these and many other fruits grow like this?

submitted by /u/Mr_JohnUsername
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Is it possible for a virus to attack your genetics? Like actual DNA or something? What would be possible through something like that?

Posted: 27 Nov 2016 06:58 PM PST

Does rice contain squalene and linoleic acid?

Posted: 28 Nov 2016 04:25 AM PST

From what I researched, only the bran contains such nutrients. Does the rice grain itself, separated from the bran, still retain squalene and linoleic acid?

submitted by /u/anemonas1
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Why does putting a hole in a balloon cause it to pop instead of leaking air from that hole?

Posted: 27 Nov 2016 03:50 PM PST

Is it possible for a disease to span across multiple branches of the animal kingdoms?

Posted: 27 Nov 2016 07:30 PM PST

Like Arthropods and vertebrates and etc. would suffer from the same disease? Like an ant and spider and snake and dog and pelican could suffer from the exact same disease?

submitted by /u/dnovantrix
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Does Carnot Heat Efficiency Only Apply to Processes of Turning Heat into Work?

Posted: 27 Nov 2016 08:53 PM PST

I've seen solar panels that have been said to have over 40% efficiency. I know the Carnot cycle applies to a heat engine, but can you generalize it to say that it's for all processes of turning heat into work?

submitted by /u/mostlyAScientist
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How do MC fusion reactors extract usable energy?

Posted: 27 Nov 2016 02:20 PM PST

Fission reactors seem straight forward enough: hot rods in water produce steam to power turbines.

Magnetic confinement fusion seems a but less intuitive. There is no contact between the plasma and structure. How does it convert this energy into electricity or another useful form?

submitted by /u/FTLSquid
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How do Micro pipettes and Pipettes function?

Posted: 27 Nov 2016 06:48 PM PST

I understand it works by vacuum, but how did engineers figure the right amount of vacuum for each value?(e.g. how much vacuum is applied to each ml)

submitted by /u/vongola17
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Is it possible for other elements to be the basis of biometabolism?

Posted: 27 Nov 2016 03:20 PM PST

I read somewhere that hydrogen and sulfur are both possible substitutes for oxygen in the form of redox energy source. How is this possible and are there any examples of organisms getting their energy this way?

submitted by /u/Epicpinguin
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Does magnetic and electric field follow surface area of a sphere?

Posted: 27 Nov 2016 04:33 PM PST

In the Biot-Savart and Coulomb's law, the denominator has r2, and it's always explained that these laws follow an inverse square relationship with distance.

Looking at the formula, though, there's a 4pi term in the denominator. Does this imply that these laws are really operating on the surface area of a sphere, given that the full denomimator is 4pir2 ? After all, the field expands in every direction, so really, saying that it follows an inverse square relationship is a shorthand way of the full explanation that it's inversely-square with distance because an inverse square (r2) means you're dividing the field strength by the surface area of a sphere of radius r.

I think this is correct, but am hoping someone can tell me if I am correct or just jumping to conclusions that don't actually exist.

submitted by /u/quesman1
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How does amusia affect speaking tonal languages?

Posted: 27 Nov 2016 02:17 PM PST

People with amusia are unable to process pitch, meaning they can't distinguish different pitches. Since tonal languages use pitches to distinguish meanings, I'd imagine people with amusia have trouble understanding it. Has there been any research on how this influences speaking and comprehension among other things?

submitted by /u/Iasper
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How does xenon gas produce a positive ion when impacted by an electron?

Posted: 27 Nov 2016 01:45 PM PST

In ion drives, xenon gas is bombarded by a electron gun which produces positive ions. The ions gets accelerated out of the spacecraft to produce thrust.

How does a negative electron make the xenon positive when impacting? Does it impact a electron in the outer shell of the xenon atom and makes it loose conection to the forces of the nucleus? If so, how come that the electrons does not immediately fill this gap to make the xenon neutral again?

submitted by /u/ForHumanitie
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Why can't we see the Andromeda Galaxy?

Posted: 27 Nov 2016 09:58 AM PST

I keep reading that the Andromeda Galaxy would be larger than the moon in our sky if we could see it. Why can't we?

submitted by /u/markahix
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Sunday, November 27, 2016

What is the difference between the local and global speed of light?

What is the difference between the local and global speed of light?


What is the difference between the local and global speed of light?

Posted: 27 Nov 2016 04:28 AM PST

As explained here you'll always measure the same value for c locally, but globally it might be lower because of gravitational fields. What I'm wondering is at what distance do you consider something to be global rather than local?

That might be a plain misunderstanding from my part, so alternatively, is it more correct that the local measurment is just an approximation of the global one, since we don't expect any significant space-time curvature in proximity of the measurment (and therefore, the measurment is actually a tiny bit inaccurate)?

submitted by /u/MightyLordSauron
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Is length contraction an optical illusion or physically real?

Posted: 27 Nov 2016 12:04 AM PST

In the Veritasium / MinutePhysics video How Special Relativity Makes Magnets Work, the explanation is that length contraction has a real physical effect. The protons become length contracted, made denser, and therefore produce a positive electric field, which repels the positively charged cat.

But... in some edge cases, it seems like this explanation would also predict some very bizarre behavior.

Let's say there's a gas cloud on the verge of becoming a star, or a star on the verge of becoming a black hole. Then let's say I start traveling at near the speed of light. From my perspective, the rest of the universe will appear length contracted. But... the video seems to say that this contraction isn't just some optical illusion, that things are really physically contracted, which can have real physical effects such as the density of charges. But if that's the case, wouldn't the almost-a-star gas cloud, or the almost-a-black-hole star, be denser? ...But only from my perspective?

submitted by /u/MoTTs_
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Why does my throat hurt when I scream or yell for long periods of time?

Posted: 26 Nov 2016 07:36 PM PST

Approximately how big was the sun when it was a planetary nebula?

Posted: 26 Nov 2016 06:01 PM PST

Can someone explain why this happens? (Link in text)

Posted: 27 Nov 2016 05:40 AM PST

In the linked video, an astronaut says that the brain shuts down the vestibular system and relies more on information that is coming from the eyes for balance coordination in microgravity. How come the brain evolved to adapt to such situations which are relatively new to the humans?

Posted: 26 Nov 2016 02:19 PM PST

Video. Are there any situations on earth where the brain has to rely on the information coming to the eyes for balance coordination? Probably this could happen if the vestibular system is damaged but in the case of astronauts the brain still switch to the eyes for balance with a healthy vestibular system.

submitted by /u/333ml
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Is there a limit on how exact weather predictions can get?

Posted: 26 Nov 2016 07:13 PM PST

I know there is some serious math and use of statistics involved and that it is under constant research.

Also, i know you can't achieve 100% accuracy for a distant future (because chaos).

But where is the point of what could be done and what couldn't

submitted by /u/cebrito
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[Physics] Why does the speed of light change with altitude?

Posted: 27 Nov 2016 06:43 AM PST

[Physics] Looking at this page here it looks that is correct. I have been wondering why.

I am thinking its to do with air pressure or to the density of the air or something.

And does the speed of LIGHT change too the closer to earth it gets?

submitted by /u/GooseNZ
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If elements are formed by atomic fusion within stars essentially at random, with some elements being more likely to arise than others, why is it that elements of a kind are always found together with more of that element?

Posted: 26 Nov 2016 03:31 PM PST

I could also have flaired this as planetary science or Earth science, but figured astronomy might be closest to the best category

submitted by /u/non-troll_account
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Why couldn't a submarine sent to Titan tap into the methane seas for the energy to explore it endlessly?

Posted: 26 Nov 2016 01:21 PM PST

In the double slit experiment, how far can you push reverse causality?

Posted: 26 Nov 2016 10:11 AM PST

I've known about the weirdness that the double slit experiment reveals for a while, but just today (reading the excellent science fiction novel The Flickermen) found out about reverse causality.

Doing research online, it seems this is scientific fact. When you do the double slit experiment using detectors to measure the stream of photons, that collapses the waveform and instead of the wave pattern, you see two lines. However, if the data from the detectors is erased, the wave pattern is seen, even though the measurement actually occurred.

This is my understanding so far.

Here's the question. What would happen if you look at the screen before looking at the data and then, while looking, someone deletes the detector data? Would the wave pattern return?

This is where I believe the novel departs from reality and my guess is once you've seen either side of the results - either the data or the pattern the waveform has collapsed and nothing will bring it back, but obviously, in quantum mechanics guessing and logic seem don't seem to play a big part...

I'm especially interested in hearing from people who've actually seen this experiment in the lab.

submitted by /u/f_leaver
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What does color mixing look like in terms of math?

Posted: 26 Nov 2016 09:10 AM PST

While working with photoshop I noticed a blend tool that could blend colors together, and then I realized that I'm not sure how it knows. Is there a mathematically process to color mixing using RGB, Hex, and/or CMYK? If so, what does it look like?

submitted by /u/Lilgherkin
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