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Sunday, July 22, 2018

Supposing I have an unfair coin (not 50/50), but don't know the probability of it landing on heads or tails, is there a standard formula/method for how many flips I should make before assuming that the distribution is about right?

Supposing I have an unfair coin (not 50/50), but don't know the probability of it landing on heads or tails, is there a standard formula/method for how many flips I should make before assuming that the distribution is about right?


Supposing I have an unfair coin (not 50/50), but don't know the probability of it landing on heads or tails, is there a standard formula/method for how many flips I should make before assuming that the distribution is about right?

Posted: 21 Jul 2018 01:22 PM PDT

Why do our ears pop when a train we’re riding enters a tunnel? Shouldn’t the pressure inside be equal to the pressure outside side since it’s open to the air?

Posted: 22 Jul 2018 06:19 AM PDT

Are there other studies on the efficacy of TDAP vaccines given to mothers during pregnancy for the protection of a newborn or is this the only one?

Posted: 21 Jul 2018 12:13 PM PDT

As the title states, I have found one study showing the efficacy of the TDAP vaccine given to mother's. (http://news.unchealthcare.org/news/2018/june/unc-study-tdap-vaccine-given-during-pregnancy-reduces-occurrence-of-infant-pertussis-reinforces-cdc-recommendations-of-immunization-for-all-mothers). However, this appears pretty recent so I don't know if it has gone through peer review and/or the results have been reproduced. I am aware of the fallacy of relying upon just one study only to find out it was an erroneous result. However, I'm not super proficient in doing scientific research and haven't found other studies.

My question is twofold: 1) At what stage of the scientific vetting process is this result/Has anyone reproduced it? 2). I know that before efficacy studies are done, there are usually safety studies completed. Can you help me find those so I can take a look at them (I'm having trouble finding studies)?

submitted by /u/annarox21
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What is the role of reactive power in transmission networks?

Posted: 21 Jul 2018 08:47 AM PDT

I've studied electrical engineering for some years, but honestly I'm still struggling with understanding complex AC concepts, especially reactive power. What's its role in transmission networks since reactive power can't do real work? Why is it important for large alternators on the grid?

submitted by /u/mrfredzzz
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Does the refractive index of a gas change with level of ionization?

Posted: 22 Jul 2018 07:46 AM PDT

I was doing some reading on refractive index of gasses and how that leads to ionospheric propagation of radio waves, but none of the resources I found explain the correlation between increased upper atmosphere ionization levels and increased angle of refraction.

I know that the precise refractive index of a gas is highly dependent on frequency, but I haven't been able to find even a vague outline of whether the refractive index of a gas goes up or down with increasing ionization, and it seems that either direction could explain the increased angle of refraction at a given frequency, depending on where in the ionosphere the "virtual reflector" is located. What papers I've found are all regarding self focusing and scattering of lasers in plasmas and such, and while the information I want might be there, it's so abstract that I can't find it.

The most logical explanation seems to be that ionized gas has a higher refractive index, which creates a tighter gradient between the index of the atmosphere (which is >1) and space (which is ~1), which leads to total internal refraction at a higher incident angle.

The other way of looking at it seems almost as logical though; that only the upper most layers of the atmosphere become ionized, dropping the refractive index of that layer closer to the ~1 of space, which still results in a tighter gradient between space and atmosphere, but at a lower altitude.

submitted by /u/hamsterdave
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What causes volcanoes to erupt?

Posted: 21 Jul 2018 08:33 AM PDT

If one makes abstraction of what they are orbiting and simply consider their composition and structure, is the distinction between large moons and rocky planets really all that significant?

Posted: 21 Jul 2018 08:58 PM PDT

Why aren't MSR reactors utilized more?

Posted: 21 Jul 2018 02:20 PM PDT

So, my understanding of MSRs (Molten Salt Reactors) is that we could use the waste from our water reactors to melt salt, use the excess heat to boil water, get a whole bunch more energy out of it than from water reactors, and wind up with waste that is only dangerous for centuries rather than hundreds of millennia.

Am I wrong? Why aren't we doing this?

submitted by /u/Cwardw
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How do they calculate the very exact hour and minute when to launch rockets?

Posted: 21 Jul 2018 06:45 PM PDT

Can someone explain Copenhagen interpretation, Many Worlds interpretation and De Broglie Bohm Pilot Wave theory?

Posted: 21 Jul 2018 04:59 PM PDT

How do you donate your liver? Dont you need it to survive?

Posted: 21 Jul 2018 11:19 AM PDT

So i was seeing a video in which a woman met the person that donated his liver to her, but how does that work? Can you survive without a liver?

submitted by /u/M33RHARIS
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How does Analgesic Gels relieve muscle pain when applied to our skin?

Posted: 21 Jul 2018 09:57 AM PDT

What makes D-Wave quantum computers considered controversial?

Posted: 21 Jul 2018 04:52 PM PDT

I see people sometimes call the computers that D-Wave makes controversial and not a "real" quantum computer. So what makes one a "real" quantum computer? Is it just people throwing shade at D-Wave, or are their computers more like pseudo quantum computers?

submitted by /u/UsernamePlusPassword
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Why is bread permanently turned into toast when we heat it, why can't we change it back?

Posted: 21 Jul 2018 03:08 PM PDT

I understand that heat can change how molecules are structured like with baking, and thats a part of it, but why does it toast, and why can't we turn it back into bread?

submitted by /u/ticktockFUCK
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Why do we hear several seconds of thunder noise after seeing a lightning?

Posted: 21 Jul 2018 12:17 PM PDT

After seeing a lightning, usually there is a 4-10 seconds of noise, despite the lightning takes only a fragment of second. What causes that long noise?

submitted by /u/NiceInformation
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What happens when an object hits another object at a velocity faster than that of a mechanical wave in either object?

Posted: 21 Jul 2018 09:32 PM PDT

I am assuming that the object would have no ability to rebound and would simply begin to plasticly deform.

submitted by /u/LianelJoseph
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Have we found decoder for the workings of inner ear?

Posted: 21 Jul 2018 08:41 AM PDT

As I understand, our inner ear encodes mechanical movement into electric signal, which is exactly what microphones also do.

I'd imagine the problem is, we don't quite know how the information is encoded, or what information aside sound itself gets translated.

Or do we? Has someone measured nerve impulses while playing specific sound and figured out how output to nerve impulse relates to input? Which would make it possible to build artificial ears or even direct audio-to-brain connection, skipping ears whatsoever?

submitted by /u/Bang_Bus
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What exactly does "non-deterministic universe" mean?

Posted: 21 Jul 2018 07:12 PM PDT

By the uncertainty principle and limitations on our computational abilities, we humans can never model the universe's evolution. Is that what non-determinism refers to? (i.e. specifically with respect to humanity's point of view)

Suppose a higher, external being was able to observe the exact state of the universe at any point in time. Can it be said that it sees the universe as deterministic?

submitted by /u/tbqh123
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Why is HIV found in semen?

Posted: 21 Jul 2018 08:26 AM PDT

HIV being a virus of the immune system, it makes sense to me that it is found in the bloodstream but not in other bodily fluids like saliva/nasal mucus/etc. So why then is it present in semen and vaginal mucus when neither of these fluids have any connection (that I know of) to immune function?

submitted by /u/willeyerasmus
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To how many digits of precision do we know the half life of Uranium 238?

Posted: 21 Jul 2018 08:25 AM PDT

Charging an electrostatic double-layer capacitor(i.e Supercapacitor) using an exterior magnetic field?

Posted: 21 Jul 2018 04:28 PM PDT

Studying about the nature of supercapacitors lead me to consider this idea:

At the discharged state of a supercapacitor, with ions spread uniformly within the electrolyte, and not connected to a power supply, only forming a circuit with a resistor. Wouldn't it be possible to separate the charges using an exterior magnetic field?

Accelerating a 2000F capacitor, in a strong magnetic field(1T+) would give rise to a Lorentz force(F = q(E + v) x B) that would separate the positive/negative ions wouldn't it?

I also think, that if the capacitor was intially charged then connected to a circuit and moved rapidly in that strong magnetic field, the discharge would be affected due to the Lorentz force acting on the (+&-)ions?

submitted by /u/9tothe9
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With two objects experiencing time dilation, is one second relative to each object itself exist the same "amount"?

Posted: 21 Jul 2018 12:19 PM PDT

From my understanding, one object will experience slower time than the other. So if there was a clock with each object, and one experienced time twice as fast, would one second be equivalent to two seconds for the other object even though they both experience "one second" the same? From an outside perspective (4D?) of the two objects, how does this work?

EDIT: Sorry the grammar in the question is awkward. I mean "does one second relative to each object itself exist as the "same amount"?" If that helps..

submitted by /u/Cynoname
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Saturday, July 21, 2018

Why do we lose the desire to eat while we are sick? (Ex. when having a cold, I lose the desire to eat)

Why do we lose the desire to eat while we are sick? (Ex. when having a cold, I lose the desire to eat)


Why do we lose the desire to eat while we are sick? (Ex. when having a cold, I lose the desire to eat)

Posted: 20 Jul 2018 01:17 PM PDT

Why does the sun's magnetic field keep changing every 11 years?

Posted: 20 Jul 2018 08:14 AM PDT

Can non-planetary celestial objects have ring systems?

Posted: 21 Jul 2018 04:14 AM PDT

Would it be possible for a star, moon or black hole, for example, to have a ring system as prominent as the ones that planets can have? If so, how would the characteristics of these ring systems differ from the ones of planets?

submitted by /u/past-the-present
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Is the neutral pion an eigenstate of mass?

Posted: 21 Jul 2018 04:47 AM PDT

So the neutral pion is written as (u anti-u minus d anti-d) (2)-1/2. So what happens when we measure the mass of the pion? Since the mass of up and down quarks is different (and antiparticles are assumed of equal mass), will we get two different values when measuring the mass of states like the neutral pion?

submitted by /u/Physix_R_Cool
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Does sexual arousal have any effect on kidneys function and urine?

Posted: 20 Jul 2018 04:45 PM PDT

I as a guy everytime I have an orgasm I feel a strong urge to pee almost right after, even If I emptied my bladder right before and I haven't drank anything in a while,

During sex after my SO has an orgasm she always goes to pee right after it happens, and tells me that she just can't help it,

I know how the blood filtration and kidneys mechanics work, but I'm wondering if being in a state of arousal (or orgasm maybe) may make urine production quicker or something like that

And if it does I'd like to ask how, why and since what age does it happen?

submitted by /u/Damnboi1221
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If solitary hunters such as raptors, ferrets, minks, and cormorants can be trained to cooperate with humans to catch prey, does this mean that pack hunting is an entirely nurture acquired trait?

Posted: 20 Jul 2018 04:52 PM PDT

How does a transistor work as an amplifier?

Posted: 20 Jul 2018 04:20 PM PDT

Do woodpeckers lose brain cells?

Posted: 20 Jul 2018 03:53 PM PDT

With all that knocking their beaks against trees do woodpeckers slowly lose brain cells? Is there a noticeable decline in brain functionality as they get older?

Edit: with sustained pecking do they cause a concussion?

submitted by /u/MisterCBax
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Is it possible to get a set of 4 points that contains 2 lines in the Fano Plane?

Posted: 20 Jul 2018 04:10 PM PDT

I have been reading "How Not to be Wrong - The Power of Mathematical Thinking" by Jordan Ellenberg. I got to the point in the book where he talks about EEC memory in computers and how it relates to the Fano Plane, he says in a foot note at the bottom of the page.

If you haven't thought about this before, you have probably found that the argument in this paragraph is hard to follow. The reason its hard to follow the reason you can't get an argument of this kind into your head by sitting and reading about it - you have to get a pen out and try to write down a set of four points which contains two different lines, and then fail to do that, and then understand why you failed

However by looking at the Fano Plane i see that points 6,7,1,3 (3 points on the side of the triangle and one in the center) are 4 points with 2 different lines, what am i not understanding here?

submitted by /u/Barry_Benson
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Would we still need Hazmat suits to cross an area effected by an airburst nuke or could we cross relatively unaffected?

Posted: 20 Jul 2018 03:43 PM PDT

What is light bar testing in the NASA sun probe?

Posted: 21 Jul 2018 01:02 AM PDT

Reuter's article with picture of light bar testing: https://www.reuters.com/article/us-space-sun/nasa-prepares-to-fly-probe-into-suns-scorching-atmosphere-idUSKBN1KA2SL?feedType=RSS&feedName=scienceNews&utm_source=reddit.com

Video of NASA performing light bar testing: https://images.nasa.gov/details-KSC-20180605-MH-LCH01_0001-Parker_Solar_Probe_Light_Bar_Test-H265-3193961.html

It looks like they're shining light onto solar panels. What kind of light and why? Maybe they're testing to see if the panels are flush, or testing the light absorption?

submitted by /u/yosimba2000
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I've often read that the forests of New England before colonization were open and park-like without underbrush and that this was because of Native Americans regularly setting fires to clear the underbrush. Is this true or was it some other set of factors that led to the park-like appearance?

Posted: 20 Jul 2018 07:27 PM PDT

What causes the ringing sensation you get in your ears after attending a loud concert? Why can it last for so long?

Posted: 20 Jul 2018 06:30 PM PDT

Why is the sea so clear in some places and so murky in others?

Posted: 20 Jul 2018 11:34 AM PDT

Obviously there will be sediment in places that rivers flow into so it's sort of obvious that the sea near river outlets would be very murky, but in places like the Maldives, the water is absolutely clear in spite of the waves churning it on the shallow beaches. There must be organic matter in the water - there's plenty living in it so there must be food and waste. Why does the debris and micro fauna/flora not cause any turbidity? Why is there no seaweed of any kind in the water? It's so clear you can see the bottom even through meters of water.

I would expect that there would be loads of small things living there that would make the water at least a little cloudy?

submitted by /u/Monguce
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Do babies sleep in the womb?

Posted: 20 Jul 2018 08:21 PM PDT

Do babies sleep during development in the womb?

submitted by /u/Iama_Kokiri_AMA
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Why do ripples form when you stretch some fabrics?

Posted: 20 Jul 2018 08:01 AM PDT

I haven't been able to google my way to an answer on this.

Take a light flexible fabric like silk or cotton and stretch it. Call the axis of the stretch the x-axis. Ripples will form in the fabric in a form resembling something like z=sin(y). My (wrong) intuition is that the force would be distributed on the x and y axes and the surface would be flat. Playing with my t-shirt on a desk makes me think there's something sort of deep going on. Very minor changes of "input" cause large changes in "output."

It obviously doesn't happen under normal conditions for some fabrics, like leather or canvas for example.

Is it possible to simulate the rippling as a boundary value problem? I assume there's a way to apply the wave equation, but I can't see it.

submitted by /u/Haus42
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Is the DNA of offspring a completely random mix of their two parents' DNA? Or are there selection mechanisms at play during gestation?

Posted: 20 Jul 2018 06:59 PM PDT

Was just reading a novel where it was suggested that human breeding tends to bring out the best characteristics of both parents in the offspring. Got me thinking whether DNA mixing is completely random or whether there is some way the new offspring is selecting the best DNA and removing the worst during it's formation.

Follow up question, how much do we really know about this process of DNA mixing during gestation (and beyond)? Where could I read more about this?

submitted by /u/BruiseHound
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Does a recipient of a bone marrow transplant develop allergies that copy the donor?

Posted: 20 Jul 2018 06:37 PM PDT

I understand bone marrow transplants and that the stem cells of the donor create the new immune system (WBC, plasma cells, antibodies, etc) of the recipient. HLA matching is to help prevent outright rejection and I also know the new immune system can attack the recipient (graft vs host disease). That said- does the recipient develop the same allergies as the donor, such as allergies to medications (ie penicillin, etc)?

submitted by /u/Jaded_rose
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If modern humans are the result of Neanderthals breeding with another species of human, why do we refer to them as separate species?

Posted: 20 Jul 2018 05:14 PM PDT

I thought a species was anything that could only produce fertile offspring with itself.

submitted by /u/BabylonBash
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Friday, July 20, 2018

What is the “pins and needles” feeling that happens when you cut off circulation to a part of your body?

What is the “pins and needles” feeling that happens when you cut off circulation to a part of your body?


What is the “pins and needles” feeling that happens when you cut off circulation to a part of your body?

Posted: 19 Jul 2018 12:27 PM PDT

About the 100 foot fissure in Yellowstone. What could that mean? What are the consequences of it opening up so suddenly?

Posted: 19 Jul 2018 08:23 AM PDT

Are allergies connected to autoimmune disease?

Posted: 20 Jul 2018 07:53 AM PDT

I have an autoimmune disease, I also have always had seasonal allergies for as long as I can remember. According to my allergists, I have been allergic to grass & corn in my twenties, but now am allergic to grass, trees, and several food items such as wheat and walnuts, but no longer corn. I've been on immunosuppressive therapies for at least 12 years, but not at times of allergy testing. Is there a link between my immune disease and the changing food allergies?

submitted by /u/LolliPoppies
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When you lose a pound, how does it get out of you?

Posted: 19 Jul 2018 07:40 PM PDT

Neurologically, what's the difference between, say, thinking of your hand moving, and actually moving it?

Posted: 19 Jul 2018 03:46 PM PDT

What assurance do we have that the Higgs field can continue to impart the same amount of mass to an object that is compressed more and more as is the case in a neutron star or singularity?

Posted: 19 Jul 2018 05:07 PM PDT

Could there be a limit to the density of Higgs bosons achievable such that beyond a certain volume the mass of an object is capped or reaches a limit and proceeding to a "singularity" is simply not possible

submitted by /u/Weaver145
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Why does the road reflect when it is hot out?

Posted: 19 Jul 2018 06:11 PM PDT

Is it true that expansion prevents huamans from ever going past the local group?

Posted: 19 Jul 2018 08:53 AM PDT

I saw a video by youtuber Kurzgesagt that said that beyond the local group (Milky way and andromeda, I think?) there expansion outweighs gravity to the extent that humans can never travel beyond it, other galaxies will always expand away faster than we can travel, is this true?

submitted by /u/gmanflnj
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How exactly do Oncologists predict how long a patient has left to live ?

Posted: 19 Jul 2018 05:29 PM PDT

How does satelite radio differ from fm or am? I can easily build a radio at home for am/fm but whats stopping me from making something that picks up satelite?

Posted: 20 Jul 2018 12:30 AM PDT

Does the brain invert the image percieved back upright if you wear inverted goggles for a certain period of time?

Posted: 19 Jul 2018 08:18 PM PDT

How do we navigate in space?

Posted: 19 Jul 2018 08:37 PM PDT

There is no azimuth, north, south, east or west. What bottom line do we base our space travel off of in order to propel in certain directions once we leave Earth's gravitational pull?

submitted by /u/pulpbear
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If temperature is the average kinetic energy in a group of atoms, why do we use Kelvin instead of Joule ?

Posted: 20 Jul 2018 04:46 AM PDT

I'm thinking a lot about entropy and information recently. Entropy is usually measured in J/K. But K seems that be also in J.

Can we consider entropy to be without dimension, the information linking a difference of temperature (a difference of energy) and energy ?

Is Kelvin used somewhat like angles in radian, to help indicate a dimension while it is in practice dimentionless ?

Can we speak of melting energy level instead of melting temperature ?

submitted by /u/Litrale
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Is there a lot of variance in the size of adult eyeballs?

Posted: 19 Jul 2018 05:55 PM PDT

Or is it mainly the eye opening that gives the appearance of large or small eyes?

submitted by /u/AsgardDevice
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Is the moon getting further away or is it getting closer?

Posted: 19 Jul 2018 09:52 PM PDT

Ever since I can remember I have always heard people say the moon is slowly getting further away from the Earth, but I just stumbled across a video of an Aerospace Engineer Major and she mentioned that the moon is getting pulled closer. I assume since she's going to college for this stuff that she would know a bit about it, but I felt like I would ask here as well.

So which one is true?

submitted by /u/CupcakeJake
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How are gas lines in cities secured from chain explosions?

Posted: 19 Jul 2018 10:10 AM PDT

I would imagine a fracture in a gas line that results in an explosion should ideally not result in a whole city blowing up due to the explosion traveling through pipes. How is that ensured though? Through using non-flamable gas concentration or some sort of blast preventing valves?

submitted by /u/voyti
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Does our atmosphere tend to settle according to density of gases, and in that case would there be a layer of methane around the planet? I just want to know if we live under a fart blanket.

Posted: 19 Jul 2018 06:36 PM PDT

How would all the moons discovered around Jupiter affect an ocean on the planet?

Posted: 19 Jul 2018 02:36 PM PDT

If the planet was solid of course. The recent discovery of 12 moons surrounding Jupiter created the thought of this question.

submitted by /u/WingoWangoJuango
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How do we perceive the color brown?

Posted: 19 Jul 2018 03:04 PM PDT

The color brown isn't part of the electromagnetic spectrum and usually results by mixing colors. Are there cones in our eye that perceived mixed signals as brown? Is it perceived later down the line at the occipital lobe due to the stimulation of multiple cones?

submitted by /u/rickbarr21
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Was the Truman Show delusion a thing before The Truman Show existed?

Posted: 19 Jul 2018 06:54 AM PDT

My understanding of this delusion is that it deals with someone who believes their whole life is a TV show. So, did this delusion exist before the movie? Or was it brought on by the movie? What was it called before the movie?

submitted by /u/j0n5n0w91
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Ion distribution within a superconductor?

Posted: 20 Jul 2018 01:44 AM PDT

Learning more about superconductors, I'm curious when the capacitor is charged and the double layer is formed, and when it discharges, are the number of positive ions equal to the negative ions?

Is there ion-uniformity when the capacitor charges or discharges? In-terms of the motion of ions, and alignment when forming the double layers.

submitted by /u/9tothe9
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What is the highest frequency laser, and what challenges exist for making a higher frequency laser?

Posted: 20 Jul 2018 01:24 AM PDT