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Monday, November 27, 2017

If light can travel freely through space, why isn’t the Earth perfectly lit all the time? Where does all the light from all the stars get lost?

If light can travel freely through space, why isn’t the Earth perfectly lit all the time? Where does all the light from all the stars get lost?

If light can travel freely through space, why isn’t the Earth perfectly lit all the time? Where does all the light from all the stars get lost?

Posted: 26 Nov 2017 10:22 PM PST

Why does space have three dimensions but time has only one?

Posted: 26 Nov 2017 09:36 AM PST

Is it possible to cause water to boil/freeze using exo/endothermic chemical reactions?

Posted: 26 Nov 2017 04:41 PM PST

What is the environmental impact of cryptocurrency mining?

Posted: 26 Nov 2017 02:12 PM PST

Most of what I have seen is simply the raw power consumption of the processing, but there is also cooling, fabrication and other costs that would also need to be considered.

submitted by /u/voideng
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Is water the wettest liquid? Is there a liquid wetter than water?

Posted: 27 Nov 2017 04:29 AM PST

Can a body be in such a shape that it has no centre of mass?

Posted: 27 Nov 2017 06:49 AM PST

Can the distribution of mass of a body, or its shape mean that there is no centre of mass for it? or is there always a centre of mass?

submitted by /u/28percentbattery
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Would our solar system look any different if the sun took longer to ignite and begin nuclear fusion?

Posted: 26 Nov 2017 09:13 PM PST

If the sun took, lets say another 10-50 million years to begin nuclear fusion, what affect would that have had on the development of our solar system?

submitted by /u/GelekW
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Does it take a computer more time or resources to compute 17*7 compared to 2*3?

Posted: 27 Nov 2017 04:08 AM PST

Also, if I keep increasing the first pair of numbers, at what point will the difference be significant?

submitted by /u/WatermelonNinja
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What causes a volcano to ash?

Posted: 26 Nov 2017 09:08 PM PST

I was watching a video on the reception eruption of a volcano in Bali and it got me thinking, if there's no organic material like vegetation to burn inside the crater, what causes a volcano to ash, or is it just hot dust?

submitted by /u/SureAsSteel
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What makes platinum so good as a catalyst for fuel cells?

Posted: 26 Nov 2017 09:39 AM PST

How common are black holes?

Posted: 26 Nov 2017 10:38 PM PST

From school It sounded like black holes form from nearly all collapsed stars. How much mass is required to form a black hole? How many of them are in our galaxy? How many orbit in our galaxy?

submitted by /u/flacidturtle1
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Does turning a CFL on and off use more electricity than leaving it on for a few minutes? What's the general rule of thumb?

Posted: 27 Nov 2017 01:21 AM PST

My father-in-law installed some new CFL lamps in his home. I noticed some rooms where they were still on even though we hadn't been in that room for over 30 minutes. He responded to this by saying something like : "CFL lamps use much less energy if you leave them on for an hour than turning them off and on".

submitted by /u/Papamje
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Where can I find a comprehensive list of all asteroids ever identified and catalogued?

Posted: 26 Nov 2017 07:54 PM PST

I found a few sources but they are all only NEO specific or special catalogs like light inversion studies.

submitted by /u/babganoush
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What is the difference between gravity and gravitational waves? And how does gravity travel?

Posted: 27 Nov 2017 06:47 AM PST

So I have read the ask reddit post in which someone asked about the best astronomy fun facts. Someone said that if the sun gets removed we still get to feel the gravity for 8 minutes, because the speed of light is the fastest rate at which information can travel. After that there was a lot of confusion about gravity and gravitational waves in the comments. Can someone explain it to me please?

Thanks a lot!

submitted by /u/Flongsch
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Are electrons literally flowing through my computer?

Posted: 27 Nov 2017 06:47 AM PST

So, the analogy I learned is that electricity is "created" when a magnet crosses a wire in motion. But, that can't possibly be creating new electrons...right? It's just exciting the electrons that are in the wire already (so I understand).

But if that's true, and the electrons flowing through my computer started in a wire from a turbine, wouldn't that wire eventually run out of electrons (assuming that turbine is powering the whole city?) I never hear about wires 'wearing out' in this way.

This leads me to believe that electrons are not literally flowing through my computer, (because if they were, the source of the electrons would be depleted eventually) but if they're not, what is?

submitted by /u/IKeepForgetting
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What is the longest nerve in the human body, anatomically speaking?

Posted: 26 Nov 2017 11:55 PM PST

Saw a related question on here and I started wondering: the sciatic nerve, which is meant to be the longest because it reaches the feet, terminates at the apex of the popliteal fossa. So what is the actual answer? Is it still considered to be the sciatic nerve because its axons technically extend to the feet? I've seen different answers, with some sources saying vagus and others saying the ulnar or radial.

In addition, what are the longest axons? Is it those of dorsal root ganglia?

submitted by /u/Pellucidumbo
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What combinations of frequencies and harmonics do musical instruments create?

Posted: 27 Nov 2017 05:44 AM PST

I'm currently writing a physics essay about frequencies of notes and chords. For the experimental part of the essay, I'm analysing the frequencies produced by said notes and chords with a Fast Fourier Transform. When playing an A4 note, for example, I see all the harmonics of the A note, as expected. However, I'm also seeing a bunch of frequencies belonging to completely different notes. Here's a picture. How can this be explained?

It is possible that I'm analysing the FFT data completely wrong, so keep that in mind.

submitted by /u/Yodaskool
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Is the air quality in major cities today worse than cities in the early 20th century like Birmingham which were industrial hubs?

Posted: 26 Nov 2017 03:56 PM PST

How does chemically and thermally strengthening glass change the structure of the material?

Posted: 26 Nov 2017 03:37 PM PST

What does chemically and thermally strengthening do to the amorphous structure of glass?

Im trying to think how or even if the structure would change or if it would just change the compression and tension forces.

submitted by /u/freekiedeekie
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Does an increase in energy also increases the amount of entropy in a system?

Posted: 26 Nov 2017 09:03 PM PST

What is the coolant in a nuclear reactor and how much pressure must it be under to persist as liquid?

Posted: 27 Nov 2017 12:36 AM PST

Just found myself wondering about this. On a previous /askscience question, u/RDS-37 posted this gif when explaining how the water moving the turbines is not irradiated. So the pressuriser keeps the coolant as liquid, but what sort of pressures are involved and how it is safely maintained?

submitted by /u/happy-little-atheist
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Sunday, November 26, 2017

What is the velocity of the edge of a bubble as it is "popping"?

What is the velocity of the edge of a bubble as it is "popping"?

What is the velocity of the edge of a bubble as it is "popping"?

Posted: 25 Nov 2017 02:01 PM PST

Take a bubble - soap/water, milk or otherwise - and initiate a "pop" from a single point on the surface. What would be the velocity of the bursting edge, as it propagates away from the initiation point?

Here is a video of some bursting bubbles in slow-motion. Notice that the bursting edge recedes from the initiation point; the intact surface remains unaffected until the bursting edge reaches it.

For simplicity, assume a perfect bubble:

  • Perfectly spherical
  • Evenly distributed surface
  • No external forces (i.e. gravity, which would cause deformation and pooling of the medium)
  • "Pop" or burst initiated from a single point on the surface

It seems intuitive that the upper limit would be the speed of sound for whatever medium the bubble was made from, because the speed of sound would be the physical limit that the information could be passed along that the bubble was popping. But I'm unsure what role the pressure differential might play - if any at all.

submitted by /u/rockitman12
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Why are non-steroidal anti-inflammatory drugs (NSAIDs) bad for inflammatory related diseases like ulcerative colitis? Why don't they help reduce the inflammation? Aren't they anti-inflammatory?

Posted: 25 Nov 2017 07:31 PM PST

How does sleeping work? I close my eyes and go unconscious. How does brain do that?

Posted: 26 Nov 2017 01:30 AM PST

How do we know the earths core is iron?

Posted: 26 Nov 2017 01:42 AM PST

In UV-Visible spectroscopy, why aren't the absorption bands infinitely thin, since the energy for each transition is very well-defined?

Posted: 26 Nov 2017 07:11 AM PST

What I mean is: why there are bands that cover a certain range in nanometers, instead of just the precise energy that is compatible with the related transition? I am aware that some transitions are affected by loss of degeneracy, like in complexes that are affected by Jahn-Teller distortion. But every absorption I see consist of bands of finite width. Why is that? The same question extends to infrared spectroscopy, with the transmittance bands.

submitted by /u/Lichewitz
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If there was a perfectly symmetrical circular spinning top spun perfectly horizontal on a frictionless platform, would it continue forever since air resistance wouldn’t be able to “grasp” on the top since there are no deformations on it?

Posted: 25 Nov 2017 08:43 PM PST

In spacetime continuum, why are we only able to move forwards in time, when we can move in any direction in space?

Posted: 26 Nov 2017 12:14 AM PST

Why doesn't the glass found within fiber optics break/shatter when the cord is bent?

Posted: 26 Nov 2017 12:52 AM PST

Glass is rigid and brittle, so how is it that you can bend it without it breaking (at least to some degree)?

submitted by /u/Javelin901
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Does light near earth experience the same acceleration due to gravity as a dropped object?

Posted: 26 Nov 2017 12:01 AM PST

To my best understanding, gravity is curvature in spacetime due to mass. What we experience as an acceleration of 9.8 m/s2 is actually just us trying to travel in a straight line through spacetime, which is warped for us mostly due to the earth's mass.

When a black hole warps spacetime enough, light does not escape.

If I fire a bullet out of a gun perpendicular to the earth, it immediately begins accelerating towards the earth's center at 9.8 m/s2, but because of its high velocity it seems to shoot mostly straight. Only over long distances do we notice that acceleration, and a bullet dropped from the height of the gun would hit the ground at the same time as the bullet fired from the gun.

So my question is, does light leaving a source near earth accelerate toward the planet at 9.8 m/s2 initially? It obviously moves so quickly away that the earth's gravity rapidly loses its effect, but does that curvature of spacetime also apply to light (and other electromagnetic radiation) near the earth?

submitted by /u/yellowboat
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Are there materials that conduct electricity but not heat? If so, what are they?

Posted: 26 Nov 2017 02:11 AM PST

How do we know what the Milky Way looks like?

Posted: 26 Nov 2017 02:16 AM PST

Since we are in the Milky Way galaxy, and it is not yet conceivable for us to send any object outside of it for observation, how do we know the shape and composition of our galaxy? Further, why does the Milky Way only take up one strip of the visible sky?

submitted by /u/alexjowski
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What was the temperature of the Moon's surface when Neil Armstrong first stepped foot on the Moon?

Posted: 25 Nov 2017 11:48 PM PST

Why does fire need oxygen, what can it do that other gasses can’t?

Posted: 25 Nov 2017 09:33 PM PST

Why isn't the ISS spun for "gravity"?

Posted: 25 Nov 2017 10:31 PM PST

What qualities of quantum fields account for their differences?

Posted: 26 Nov 2017 07:05 AM PST

My understanding of quantum field theory is that all particles are now seen to be disturbances in a field - the electron field, the electromagnetic field (photon), the gluon field, and so on. To me this sounds like saying that everything is made of one kind of stuff: a field. But the way these fields behave seem very different: one is influenced by massive bodies, one is influenced by charged particles, disturbances in one produces one kind of particle, another produces a very different kind of particle. But isn't a "field" just a number assigned to every point in space? What qualities do fields have that produce such different behaviors? How can a field be said to be different than another field, other than its strength at a given point in space?

submitted by /u/harumphfrog
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Why do "small" changes of temperatures caused by climate change (0-2° C) cause such drastic effects?

Posted: 26 Nov 2017 03:01 AM PST

I am not a climate change denier, I've just been too scared to ask this question for quite a long time --- why do what I would consider "small" changes of the temperature of the earth cause things like the melting of glaciers in Antarctica?

submitted by /u/RealShigeruMeeyamoto
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What causes the muscle aches when a person has the flu?

Posted: 26 Nov 2017 12:20 AM PST

And, are there useful remedies that can treat the cause instead of just painkillers?

submitted by /u/BotiaDario
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Why is it that dilute sulfuric acid is more corrosive than its concentrated counterpart?

Posted: 25 Nov 2017 10:14 PM PST

I was talking with an industrial chemist and he brought up the fact that 99% sulfuric acid will do little damage to you relative to a more diluted solution. His reasoning was that there need to be water molecules in the solution to be converted to hydronium which then cause damage. If that's true, why is it that hydronium is the one causing damage to a person's skin/body and not sulfuric acid when they have pKa values of -1.7 and -3, respectively? Why can't sulfuric acid directly protonate the body's fats/proteins/etc which then causes visible damages and burns?

submitted by /u/VeraMar
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[Biology] Why do bananas have those shiny crystals on them? What are they?

Posted: 25 Nov 2017 11:19 PM PST

How do Scientists derive formulas and constants?

Posted: 25 Nov 2017 04:04 PM PST

For example how did Newton know the Force is equal an objects mass times it's acceleration (F=ma)? And how are constants found (like G which is 6.67x10-11 )? Thank you!

submitted by /u/IanCarteriDubbbz
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What are the origins or predicted origins of gold and silver on planet Earth?

Posted: 25 Nov 2017 07:29 PM PST

Could earth’s GPS satellite network be used on the moon for telemetry purposes?

Posted: 25 Nov 2017 08:27 PM PST

Is the signal strong enough?
Are the angular changes drastic enough for an antenna to pinpoint location?

submitted by /u/mikebellman
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Saturday, November 25, 2017

What is the body's conversion efficiency of energy stored in food to energy stored in fat, or energy available to do work with?

What is the body's conversion efficiency of energy stored in food to energy stored in fat, or energy available to do work with?

What is the body's conversion efficiency of energy stored in food to energy stored in fat, or energy available to do work with?

Posted: 25 Nov 2017 01:08 AM PST

For example, if I eat 1000 calories of sugar:

  • How many calories will be stored in fat (assuming none of the calories are used for exercise etc).
  • How many calories are available to perform work with (after the body has converted the sugar to ATP, etc). The assumption is that the conversion process from Sugar --> X --> ATP --> ? is not 100% efficient.
  • How do the above numbers differ for different sources of energy. For example does eating 1000 cal of fat result in the same number of calories available for work as eating 1000 cal of sugar?

Bonus question:

  • How efficient is the body in converting the energy stored in fat to energy available for work (e.g. ATP)

Note: I am not a biologist, from my understanding ATP is the last form of energy muscles use, albeit I could be wrong.

submitted by /u/YbgOuuXkAe
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Does boiling water in a low pressure atmosphere still kill pathogens?

Posted: 24 Nov 2017 09:44 AM PST

Reducing the atmospheric pressure will reduce the boiling temperature of water, so will boiling in low pressure still kill pathogens in the water?

submitted by /u/xzez
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At what point does atmospheric friction from high speeds negate wind chill effects?

Posted: 24 Nov 2017 07:30 PM PST

What distance from the centre of the earth is an object's potential energy the greatest?

Posted: 24 Nov 2017 11:19 PM PST

As you move a rock further away from the centre of the earth you are increasing its potential energy. If I pick up a rock off of the ground and move it 10 feet up I've just added energy to the system.

Now as you get further from the earth, the gravitational pull weakens by the a factor of 1/(distance)2.

At what point is the rock at the sweet spot where it's potential energy is the greatest it can possibly be and moving further from the earth will reduce potential energy at that point? At what distance does the potential energy become near zero and the rock becomes "weightless?"

submitted by /u/Invrlose
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Particles in Space.. is Space a gas?

Posted: 24 Nov 2017 06:12 PM PST

Matter, in the form of a gas is when "the atoms or molecules in gases are more widely spaced than in solids or liquids and suffer only occasional collisions with one another."

On sea level, one cubic cm of air has about 30 quintillion particles. Space, although often said not to, contains more than nothing. In our solar system, about there are about 30 particles per cubic centimeter. Can someone explain what these particles are?

Considering how far apart the particles in our solar system are spaced from each other, would they be considered a gas? If not, what are they? Are these particles anything? What thing are they? What type of thing?

Considering any of these question are a yes, would the Space we know be considered a mixture?

submitted by /u/ztamm
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Is it possible to study fields in space rather than excitations of those fields?

Posted: 25 Nov 2017 03:02 AM PST

I was wondering if it is even theoretically possible if we can directly study and measure quantum fields that 'make' subatomic particles like the electron field. Rather than study the electron itself? Thanks in advance for the answers!

submitted by /u/JackTalle
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Why can't we make pacemakers that can withstand magnetic fields?

Posted: 25 Nov 2017 04:32 AM PST

The pacemaker sign is often found near strong magnetic fields. What's blocking us from making them non-sensitive to magnetic fields?

submitted by /u/Helmarche
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If calcium is a metal, can it be used for things like electric circuits? Can it be smithed?

Posted: 24 Nov 2017 08:50 PM PST

I just found out it was a metal.

submitted by /u/ten_mile_river
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Does the magnus effect still work underwater?

Posted: 25 Nov 2017 03:13 AM PST

Scramjets and Entropy - The reason for thrust?

Posted: 24 Nov 2017 06:23 PM PST

I have taken Thermodynamics I and II in college. I was reading through my textbook and it said that there is a velocity drop in a supersonic flow stream when a heat transfer to that system occurs. If this is the case, how does it produce thrust?

submitted by /u/Fuck__living
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What happened to the Global Cooling scare of the 1980's?

Posted: 24 Nov 2017 09:13 AM PST

Not that I don't believe in global warming or anything, but im just generally curious

submitted by /u/Lendesnia
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How do satellites survive in the thermoshere when they should melt?

Posted: 24 Nov 2017 09:06 PM PST

By what mechanism does the brain keep time?

Posted: 24 Nov 2017 02:55 PM PST

In every time-measuring device we have, we need mechanical parts that follow a certain rhythm to keep time, so wouldn't the brain also require some physical mechanism in order to perceive time? If so, how does that mechanism work?

submitted by /u/Tendy777
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Do we know how many tons of CFC are in the atmosphere?

Posted: 24 Nov 2017 08:53 PM PST

A question about the relativity of velocity?

Posted: 25 Nov 2017 06:17 AM PST

If all movement is relative to some other reference point, then we could say that we are moving at near light speed compared to a particle in an accelerator. Instead of the particle coming towards us, we would be going towards the stationary particles at near light speed.

If this is true, then why aren't we moving forward in time more slowly compared to the particles? According to the theory, objects that move faster in space experience time more slowly compared to other objects. In other words, time moves faster for slower objects.

If anyone has some knowledge to share on this please do so because it is something that has been bugging me for a while now.

submitted by /u/_Haxington_
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What's to stop a spinning object surpassing the speed of light, if large enough?

Posted: 24 Nov 2017 06:15 PM PST

Let's say you had a giant compass needle spinning in space.

Diameter of the needle = 95,426,903.18 metres

Spin circumference = 299,792,458 metres (the distance light travels per second).

If it were to spin at >60rpm the ends of the needle would (on paper) surpass the speed of light. Can anybody explain what would actually happen? Would the needle be forced to bend, regardless of its material?

submitted by /u/Zombreeez
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What's the state of current lithium-ion batteries and what improvements can we expect in for batteries in general in the short term?

Posted: 24 Nov 2017 02:59 PM PST

Question from my 4 year old sister, do other animals also get "Boogers"?

Posted: 24 Nov 2017 07:02 AM PST

I was telling my sister that she shouldn't pick her nose in public, and somehow she asked me if our dog also couldn't. I told her that animals don't get them. She asked why and I had no idea, in fact I didn't even know if me saying that they don't get them was accurate.

It's my understanding that "boogies" are dried muccus. When something irritates the lining of your nose, like dust, or powder, that muccus stops it. So, does the differing nasal cavity shape on other animals stop them from getting them? Do other animals lack that same muccus?

submitted by /u/SomecallmeMichelle
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How do we clear out dust/debris/lint that gets into our lungs from breathing?

Posted: 24 Nov 2017 02:51 PM PST

As the question states, clearly we breathe in minute particles of dust everywhere we go that must build up over time. Is it all captured by the cilia lining our respiratory tract? But even if they were caught on the way down, there is no way of clearing it unless it's in the nose so how come after decades of living people don't have to clean out their lungs like they would a dusty old room?

submitted by /u/synapgorithm
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How does the brain produce chemicals like dopamine, serotonin, etc?

Posted: 24 Nov 2017 06:00 PM PST
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