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Monday, October 31, 2016

How many numbers a & b exist such that a^b = b^a? How many rational numbers? Integers? Or is there a way to prove that there is an infinite amount?

How many numbers a & b exist such that a^b = b^a? How many rational numbers? Integers? Or is there a way to prove that there is an infinite amount?


How many numbers a & b exist such that a^b = b^a? How many rational numbers? Integers? Or is there a way to prove that there is an infinite amount?

Posted: 30 Oct 2016 11:10 AM PDT

ab = ba

I'd assume there are a infinite amount of numbers and maybe even rational numbers. I'm more interested in integers.

From what I've seen, it works when b = a (aka aa = aa), but that's a trivial solution. The only non trivial solution I found was 24 = 42.

submitted by /u/StormStooper
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If the Alps were created 50 million years ago from Africa and Southern Europe colliding, and raising what used to be a sea bed between them. Couldnt we search mountains for fossils earlier than the majority we find ?

Posted: 30 Oct 2016 08:21 PM PDT

The title explains it all could we search mountains for amazingly ancient fossils given the nature of their creation?

Thank you in advance

submitted by /u/LambentGoku
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Has anyone computed the number of unique length "n" string of numbers in the "m"th decimal approximation of pi?

Posted: 31 Oct 2016 07:36 AM PDT

It is not known whether it is possible to find an arbitrary sequence within the decimal expansion of pi, or for that matter, some other transcendental answer (where the answer isn't trivially "no" like the Liouville constant).

However, have people done any work to see if all strings below a certain length are present, and how the percentage of these strings that are present increases as you increase the number of digits in the decimal expansion of pi?

I noticed in this site: http://www.angio.net/pi/piquery that has pi calculation to 200 million places and the probability a string of length "n" is present seems to drop by about a factor of 10 each time, essentially consistent with sampling from a random string. Essentially I want to know what work has been done, either analytically or numerically, to see if the expansion of pi behaves the same as a random string for the purposes of sampling.

submitted by /u/somedave
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How are rates of mountain growth calculated?

Posted: 30 Oct 2016 08:33 PM PDT

After working as a dishwasher for a couple of weeks, my hands could handle a lot more / hotter water. How does the human body adapt to direct contact with heat?

Posted: 30 Oct 2016 03:15 AM PDT

Genetics: During genetic drift, as alleles are lost, which increases? Homozygosity or Heterozygosity?

Posted: 30 Oct 2016 07:38 PM PDT

I'm analyzing a paper for a piece of university coursework and one of the questions is asking me to identify an "important typographical error" in the main text of the introduction.

My friends are struggling, but one of them things they have found it. But I'm not so sure. The sentence reads as follows:

"As alleles are lost, homozygosity necessarily increases"

Is this correct? Or is 'heterozygosity' meant to be in place of 'homozygosity? Or perhaps 'decreases' in place of 'increases'?

Any ideas?

Link to paper: http://www.d.umn.edu/~jetterso/Ecological%20Genetics/documents/NewmanandPilson1997Effectivepopulationsize.pdf

Sentence can be found at the top of the second column, first page of introductory text.

EDIT: Solved, Thanks

submitted by /u/ZaneT_
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Why does the iron in our food not react with acid and form hydrogen gas? If it does , how does it affect the body ?

Posted: 31 Oct 2016 03:08 AM PDT

Are satellites engineered differently for specific planetary orbits?

Posted: 30 Oct 2016 04:38 AM PDT

I'm currently doing an assignment on Mars colonisation and launching a GPS satellite system there. Would we have to engineer these satellites differently to make them orbit Mars in a way that could be used for GPS?

I'm having trouble on finding any information about making different satellites for different planets, maybe I'm just bad at google, but if someone could provide some information (and hopefully sources?) it'd be greatly appreciated.

submitted by /u/J3ST_eR
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What is the oldest known case of Bi Polar Disorder, specifically manic episodes?

Posted: 31 Oct 2016 12:24 AM PDT

How did people finally realize that it was a mental disorder and not (witchcraft or demons), and, what would happen to a person with an untreated manic episode in the wild. Is there any documentation in history of people following someone with it in history. Also, would it reverse, or get worse, or death if untreated?

submitted by /u/Aguy00
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How does General Relativity predict specifically the existence of Gravitational Waves?

Posted: 30 Oct 2016 12:23 PM PDT

All I can find is the simple claim that GR shows gravity propagating at finite speed, like any wave.

I can't find any descriptive information beyond that. How do these waves form exactly? I've been browsing some of the LIGO recaps and seen claims that the system ejected 3 solar masses in the form of GW radiation. How does the theory of GR predict such radiation?

There's also some claims where they relate GW propagation to accelerating bodies, but I can't find further information at all. Also something about "chirps" in the LIGO data being somehow important, which I'm reading more about now.

Can anybody give some input to the relationship between GW's and the predictions of GR?

submitted by /u/The_Sodomeister
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When you light a propane torch, why does the fire not also ignite the gas inside the canister?

Posted: 30 Oct 2016 03:18 AM PDT

Probably sounds like a stupid question to many but I'm struggling to imagine the science behind it.

If you had a watering can full of petrol and lit the sprinkles of petrol coming out of the nozzle, you'd rightfully expect to have the can explode in flames.

If you sealed the can, would that be any different? What about if you sealed the can and pressurised it?

Does the pressure have to be high enough that the speed of fuel coming out of the nozzle is higher than the speed that the fire can move towards the fuel source?

submitted by /u/randomusername1198
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How are we able to store data in diamonds?

Posted: 30 Oct 2016 02:22 AM PDT

In reference to this post: https://www.reddit.com/r/worldnews/comments/5a4u4w/its_well_known_that_diamonds_are_extremely/

This is not the first time I've read about this but I never looked into it. What is the scientific logic behind being able to store data in diamonds?

submitted by /u/ajs427
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Hoew much can we really tell about interbreeding of species just by looking at their DNA?

Posted: 30 Oct 2016 03:58 AM PDT

Hi everyone,
I just read this article called "Aboriginal Australians, Pacific Islanders carry DNA of unknown human species, research analysis suggests" which popped up in r/all.
In this article they for example state: They found Europeans and Chinese people carry about 2.8 per cent of Neanderthal DNA.
My question is how come the percentage is so low? Neanderthales and homo sapiens evolved from a common ancestor. Shouldn't we carry around 98%+ of the same DNA?(We and chimps have around 99% of DNA in common)
Another question that popped up is whether having something genetically in common really means we did interbeed with the ancestor of this species. We can have proteins in common just because we evolutionary needed it to eveolve the same way(I have alcohol dehydrogenase in humans and fruitflies in mind).
So in general how much can we really tell about interbreeding of species just by looking at their DNA?
Thanks for all your answers in advance

submitted by /u/g0lmix
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Light Speed — Can we trust the measurements?

Posted: 30 Oct 2016 08:10 AM PDT

I presume we use atomic clocks to time the speed of light, but how can we be certain that this is an accurate method of measurement if they themselves are make use of these "electromagnetic waves" to time periods of time. Doesn't that falls into a circular reasoning thing? Making use of something that travels at the speed of light to measure the speed of light?

submitted by /u/heedme
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Why do high temperatures denature enyzmes, but low temperatures do not?

Posted: 30 Oct 2016 06:18 AM PDT

Why is the European Extremely Large Telescope projected to be operational for 10 years? Why even establish a limit before its even built?

Posted: 30 Oct 2016 02:35 AM PDT

So apparently the E-ELT will be operational from 2024 until 2034. Are they already planning on building a new one ready for 2034?

submitted by /u/launcher87
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Conceptually, how does quantized energy resolve the UV Catastrophe?

Posted: 29 Oct 2016 08:00 PM PDT

I understand the mathematics of why it works out like this, but can't wrap my head around it conceptually.

Rayleigh Jean's law implies that a black body will radiate infinitely intense light for arbitrarily small values of the wave length:

Intensity p(f) = (8πkTf2 )/c3 approaches infinity as wavelength approaches 0. This obviously isn't true because we aren't all getting burnt to a crisp.

And, as I mathematically understand it, introducing discrete energy values E = nhf results in the proper equation:

p(f) = (8πhf3 /c3 )(1/ehf/kt -1) so that intensity approaches 0 for smaller wavelengths, and peak intensity is at the center of the distribution just as observed in actual black bodies.

Physically, though, what is going on that causes this? What I'm thinking is that, because the energy values are discrete, it's a less common occurrence for the oscillators to emit shorter wavelength photons because that represents an electron's long fall from higher energy levels to lower ones, and it's just more common for it to fall through less energy levels.

Is this explanation anywhere close to what's going on?

And, let's for a second imagine that the UV Catastrophe was true, and the universe is classical in this regard. What is the inverse of my question? What causes there to be seemingly infinite energy in the black body lacking quantization despite not having an infinite temperature?

Also, how exactly did Planck derive the quantum intensity equation once he assumed quantized energy:

p(f) = (8πhf3 /c3 )(1/ehf/kt -1) ?

submitted by /u/cosekantphi
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Sunday, October 30, 2016

Can stars exist that are arbitrarily close to becoming a black hole?

Can stars exist that are arbitrarily close to becoming a black hole?


Can stars exist that are arbitrarily close to becoming a black hole?

Posted: 29 Oct 2016 10:21 PM PDT

That is, can the radius of a star be arbitrarily close to the Schwarzchild radius for its mass? Or is there a certain radius past the Schwarzchild radius below which a stable star cannot exist, and the star must collapse into a black hole?

submitted by /u/bolj
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If gravity "travels" as a wave, does it move at the speed of light?

Posted: 29 Oct 2016 06:09 PM PDT

In science we were all taught that all matter has mass, and thus gravity. That gravity extends across the entire universe, and gets weaker the further you are from the center of mass.

So, since LIGO has detected gravitational waves, how fast do those waves move? Do they "travel" at the speed of light and behave the same as any other electromagnetic wave?

submitted by /u/MrSquer
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Why don't solids sublimate in space?

Posted: 29 Oct 2016 07:38 PM PDT

There's basically zero vapor pressure in space so shouldn't things spontaneously turn to gas?

submitted by /u/tylerchu
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If a person is a blood-type match for a blood transfusion, would they also be a match for bone marrow or organ donation?

Posted: 29 Oct 2016 08:37 PM PDT

Are protons from different elements identical?

Posted: 29 Oct 2016 06:04 PM PDT

Here's what I understand:

Atoms are made of protons, neutrons and electrons.

What differentiates elements from each other is the number of protons contained within their atoms. E.g.; Hydrogen only has one proton, whereas Neon has 10 protons, Calcium has 20 protons, etc.

But here's what I don't get: if you took the proton from an atom of hydrogen, and compared it to a proton taken from Calcium, would they be identical?

Put another way, do the subatomic particles of hydrogen have an intrinsic 'hydrogen-ness' to them, or are they entirely interchangeable with the particles of other elements?

Could you theoretically remove a proton from a Calcium atom, and replace it with a proton from a Cadmium atom and still have an atom of 'pure' Calcium?

Thanks in advance

submitted by /u/Roy4Pris
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Why do some chemical elements with a higher atomic number than the preceding element have a lower weight? (E.g. Argon has atomic number 18 and weight 39.948, and Potassium has atomic number 19 and weight 39.0983.)

Posted: 29 Oct 2016 02:00 PM PDT

Other examples include Thorium with atomic number 90 and weight 232.0377 and Protactinium with atomic number 91 and weight 231.03; Uranium with atomic number 92 and weight 238.02 and Neptunium with atomic number 93 and weight 237; and Bohrium with atomic number 107 and weight 272 and Hassium with atomic number 108 and weight 270.

My understanding was that as the atomic number goes up, so does the number of protons, so shouldn't the weight always go up as more protons are added to a nucleus?

submitted by /u/BOLDTHUMB
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Why aren't there any medical uses of exoenzymes?

Posted: 29 Oct 2016 03:14 PM PDT

It seems that some exoenzymes could be really clinically useful in targeting particular kinds of cancer - hyaluronidase, which breaks down the packing tissue between cells, delivered to cancerous tumors was just something that I thought of. Or why not use leukocidins to treat autoimmune disorders? I asked my microbiology professor, and she said she didn't know of any clinical applications, so I thought I'd ask here why/if that's the case. Thanks!

submitted by /u/glovesforfoxes
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[Computing] How to compute the determinant of a large matrix with optimal precision?

Posted: 29 Oct 2016 08:05 PM PDT

For a cluster computing competition a couple years back, the challenge was to compute the determinant of a 5000x5000 square matrix (25,000,000 elements) consisting of double-lengths integers. My original idea was to row reduce the matrix and multiply the diagonal, but that seems like it would run into problems with the sheer quantity of multiplication that would need to occur leading to a reduction of precision. The goal of the competition was to be "accurate" (but that wasn't really defined very well) and to be the quickest to this "accurate" result. What methods would provide a quick and reliable answer, Reddit?

submitted by /u/AeroMech08
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Salt Water Crocodiles are said to have changed very little since 'dinosaurs roamed the earth,' is this exclusively because of their apex position in the food chain, or do their offspring show a lower rate of genetic mutation?

Posted: 29 Oct 2016 07:29 AM PDT

As in the title, 'lower rate' as compared to higher mammals, which developed more recently.

submitted by /u/IAMA_JERK_AMA
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Why do hard drives not hold their specified storage amount?

Posted: 29 Oct 2016 07:49 PM PDT

I've bought a couple of hard drives for my electronics (i.e. Xbox and PC), but they never hold the correct amount of storage. Example: I bought a 500 gb hard drive for my PC, but it can only hold 232 gigs. Why does this happen? How can I fix this?

submitted by /u/Vessure
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Could black holes have been predicted using Newton's laws?

Posted: 29 Oct 2016 09:21 AM PDT

Are there any animals that make tools for the purpose of improving or refining other tools?

Posted: 29 Oct 2016 09:28 AM PDT

I know that tool construction has been observed in animals in the wild (IIRC by Jane Goodall), but that was single construction to get food. What about making a tool to make another tool better?

submitted by /u/skurvecchio
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Do people with hyperthymesia remember dreams better than the average person?

Posted: 29 Oct 2016 09:29 AM PDT

Just curious if the memory loss of dreams is consistent throughout all humans.

submitted by /u/An_Actual_Moose
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What is the evidence for circular indentations in the front of frills of ceratopsians?

Posted: 29 Oct 2016 09:00 AM PDT

Many paleoartists have recently depicted ceratopsians with circle indentations in the front of their frills. There are circular openings in the bone in some cases - in Torosaurus, for example - but what is the evidence for there being indentations in the skin? Also, what is the evidence for the indentations in the front of the snouts that many paleoartists depict?

submitted by /u/dgmilner
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How does the human body notice that you have digested foul or poisonous food & how long does it take to launch countermeasures?

Posted: 29 Oct 2016 08:33 AM PDT

(Mathematics) Does the sum of all real numbers equal -1\12?

Posted: 29 Oct 2016 03:26 PM PDT

It was under my impression that you could not do arithmetic with inifinity or infinite sums for that matter, so all the proofs showing that the sum of all numbers equals -1/12 seemed kind of bogus to me. However I've heard that it's very important to string theory, so I'm kind of lost. Does it or doesn't it equal -1/12? Thanks. Edit: some grammars

submitted by /u/jobonso
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[physics] Assuming earth was a perfect sphere, how far off the surface would the light have to pass in order to orbit it?

Posted: 29 Oct 2016 09:39 AM PDT

Basically can light orbit earth and if so, is it possible to detect? Or does the landscape render that outcome void?

submitted by /u/Pilotwannabe21
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Does white noise have any effect on concentration or memory?

Posted: 29 Oct 2016 12:43 AM PDT

If so, is this effect quantifiable in any way? Are there changes in brain activity when studying with or without the presence of white noise?

submitted by /u/Kingkururu
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If 0*0=0, wouldn't that mean that 0=0/0?

Posted: 29 Oct 2016 11:50 AM PDT

If not clear:
0 (first zero) * 0 (second zero) = 0 (third zero) -> 0 (first zero) = 0 (third zero) / 0 (second zero)

submitted by /u/The_Godlike_Zeus
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How do we know that action must be least ( stationary ) ?

Posted: 29 Oct 2016 06:00 AM PDT

There are a lot of explanations on how to minimize the action and that newtonian and lagrangian mechanics give the same answer, but how do we know that action must be least ? Can it be shown that newtonian mechanics somehow implys that action must be least ? ( sorry for my english ) ?

submitted by /u/Coousey
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Saturday, October 29, 2016

We are scientists from the Society of Vertebrate Paleontology coming to you from our annual meeting in Salt Lake City. We study fossils. Ask Us Anything!

We are scientists from the Society of Vertebrate Paleontology coming to you from our annual meeting in Salt Lake City. We study fossils. Ask Us Anything!


We are scientists from the Society of Vertebrate Paleontology coming to you from our annual meeting in Salt Lake City. We study fossils. Ask Us Anything!

Posted: 29 Oct 2016 06:05 AM PDT

Hello AskScience! We are members of the Society of Vertebrate Paleontology. We study fossil fish, mammals, amphibians, and reptiles — anything with a backbone! Our research includes how these organisms lived, how they were affected by environmental change like a changing climate, how they're related, and much more.

You can learn more about SVP in this video or follow us on Twitter @SVP_vertpaleo.

We're at our 76th Annual Meeting in Salt Lake City, Utah. Ask us your vertebrate paleontology questions! We'll be here to answer your questions at 10am Mountain Time/12pm Eastern!

submitted by /u/VertPaleoAMA
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Are organelles inside cells actually colored?

Posted: 28 Oct 2016 08:27 AM PDT

In cell models you can see the organelles colored in certain ways. Are they actually colored like this, or are they colored that way so we can differentiate them.

submitted by /u/TheFaeranBlade
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How can there be a speed difference at joining rivers at an Y-shape?

Posted: 29 Oct 2016 04:55 AM PDT

Im in a discussion with my colleagues on how water flows, we are working on an inland barge.

We are moving upstream from point C moving to point A.

My colleague says that when we cross from C to A we suddenly move quicker because there is less water coming from A.

How is this possible?

If it flows faster wouldn't it "bump" into the water from B and then slowdown?

https://imgur.com/gallery/CLfBE

submitted by /u/meijboomm
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Why do beavers build dams?

Posted: 28 Oct 2016 09:21 PM PDT

First: I'm unaware of an "ask an animal expert" subreddit, so I hope this still fits here. Second: The most common answer as discovered by google searching suggests that beavers are seeking calmer waters to build their home. This doesn't sound like the end of the story to me. Surely if a beaver simply wants calmer water, they'd seek calmer water. I feel like there has to be more to the behavior, so I'm curious.

submitted by /u/SRMTYPST
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What happens when a sound wave encounters a vacuum?

Posted: 28 Oct 2016 11:42 AM PDT

We know that sound doesn't travel through a vacuum, but something has to happen to the energy of the sound wave when it hits a vacuum. Does it bounce back in the opposite direction? If so, what prevents spacecraft from constantly ringing like a bell? I'm guessing the sound energy will eventually become heat, but doesn't this take some time?

submitted by /u/sacrelicious2
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How do chromosomes survive in the cytoplasm during mitosis?

Posted: 28 Oct 2016 01:50 PM PDT

I've been taught that DNA cannot survive in the cytoplasm which is part of why transcription must occur in order to send information out of the nucleus and why RNA must be given a poly-A tail before leaving the nucleus. During mitosis however, the nucleus dissolves but the chromosomes survive enzymatic degradation. Just wondering what is done to the chromosomes to allow this?

submitted by /u/WilsonWilson64
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DNA replication - is the leading strand always built complementary to either the coding strand or the template strand?

Posted: 28 Oct 2016 03:19 PM PDT

So let's say we have a strand of DNA, which is going to be replicated. Helicase begins to unwind one side of the DNA. You won't see both ends being unwound.

I assume this means that replication will always start on one particular end of a DNA strand. Which I suspect means that the leading strand will always be complementary to one particular strand of DNA every time (which will be either the coding or the template strand).

I can't find any source for this at all. Is the leading strand always complementary to the coding strand, or is the leading strand always complementary to the template strand?

submitted by /u/Bob523623424
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Is there a series that always ends up inconclusive no matter which test you use?

Posted: 28 Oct 2016 12:21 PM PDT

If there is an absolute zero, is there a finite rate at which a given object's temperature can be lowered?

Posted: 28 Oct 2016 05:24 PM PDT

My understanding is that the colder a cooling medium is, the faster heat will transfer to that object, so I'm wondering if we can calculate the maximum rate of cooling as a physical limit or whether it's defined by the two substances properties?

submitted by /u/Caridor
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What gives the Squid nebula its stretched oval shape?

Posted: 28 Oct 2016 06:02 AM PDT

Hey today on r/space they were showing this picture made buy Rolf Geissinger of the Squid Nebula:

http://apod.nasa.gov/apod/image/1610/Sh2-129+OU4+vdB140_Rolf-Geissinger.jpg

What gives the nebula this shape?

To my untrained eye it looks like the red cloud is some kind of super nova remnant. kind of like the other one around the star at the bottom left-middle of the picture.

Then there is the central blue-white cloud. Is it a disc like object seen edge on? Is it one bright star at the center or one bright one and multiple others?

submitted by /u/zwiebelhans
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Would earphones work in space?

Posted: 28 Oct 2016 05:10 AM PDT

You are wearing earphones connected to a mobile while being in space without a spacesuit, let's imagine you would not freeze to death or suffocate in seconds. Would you be able to hear any sound at all, or feel any vibrations in your ears?

submitted by /u/ScamPictures
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Is there any instance of an exoplanet orbiting three separate stars, or is this not even possible?

Posted: 28 Oct 2016 06:36 AM PDT

How do computers keep track of time?

Posted: 28 Oct 2016 12:41 AM PDT

That little boring fact about computers has always fascinated me, how can electrons keep track of time? Stuff like, how clock cycles are managed, how hertz are measured and throttled through every piece of hardware and interface data delivery. It blows my mind. What piece of hardware is measuring the time? How is that done?

submitted by /u/cephsdiablo
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