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Please read this entire post carefully and format your application appropriately.

This post is for new panelist recruitment! The previous one is here.

The panel is an informal group of redditors who are either professional scientists or those in training to become so. All panelists have at least a graduate-level familiarity within their declared field of expertise and answer questions from related areas of study. A panelist's expertise is summarized in a color-coded AskScience flair.

Membership in the panel comes with access to a panelist subreddit. It is a place for panelists to interact with each other, voice concerns to the moderators, and where the moderators make announcements to the whole panel. It's a good place to network with people who share your interests!

You are eligible to join the panel if you:

  • Are studying for at least an MSc. or equivalent degree in the sciences, AND,

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  • Choose exactly one general field from the side-bar (Physics, Engineering, Social Sciences, etc.).

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Ideally, these comments should clearly indicate your fluency in the fundamentals of your discipline as well as your expertise. We favor comments that contain citations so we can assess its correctness without specific domain knowledge.

Here's an example application:

   Username: /u/foretopsail
   General field: Anthropology
   Specific field: Maritime Archaeology
   Particular areas of research include historical archaeology, archaeometry, and ship construction. 
   Education: MA in archaeology, researcher for several years.
   Comments: 1, 2, 3, 4.

Please do not give us personally identifiable information and please follow the template. We're not going to do real-life background checks - we're just asking for reddit's best behavior. However, several moderators are tasked with monitoring panelist activity, and your credentials will be checked against the academic content of your posts on a continuing basis.

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Stickied post

We are an international team led by the Max Planck Institute for extraterrestrial physics (MPE) in Garching, Germany, in conjunction with collaborators around the world, at the Paris Observatory-PSL, the Universite Grenoble Alpes, CNRS, the Max Planck Institute for Astronomy, the University of Cologne, the Portuguese CENTRA - Centro de Astrofisica e Gravitacao and ESO.

Our observations are the culmination of a 26-year series of ever-more-precise observations of the centre of the Milky Way using ESO instruments. The observations have for the first time revealed the effects predicted by Einstein's general relativity on the motion of a star passing through the extreme gravitational field near the supermassive black hole in the centre of the Milky Way. You can read more details about the discovery here: ESO Science Release

Several of the astronomers on the team will be available starting 18:30 CEST (12:30 ET, 17:30 UT). We will use the ESO account* to answer your questions. Ask Us Anything!

*ESO facilitates this session, but the answers provided during this session are the responsibility of the scientists.


I read that Parker's theory about the existence of solar winds was met with controversy since the predominant consensus back then was that space was a complete vacuum.

So how did they explain auroras (that are caused by charged particles carried by solar winds interacting with our magnetosphere)?


EDIT: Wow thanks for all of the answers and the support, this is my most popular post yet and first time on trending page of this sub! (i’m new to reddit)

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There are never too many cooks in the kitchen! Sign up for Reddit Gifts CookBook exchange by August 19th and share the love!


So first let me say I am so excited to find this page, I’ve been looking for something like this for a long time.

So the universe started x number of years ago (13.6 billion?) and so that is the limit of what we would be able to see. Ultra deep field I believe saw up to around 13.2? Billion light years away (essentially 13.2 billion years into the past).

And I believe it would have been the same story if it was pointed at a completely different part of the sky. And also would be the same if someone way out there had one pointing at us.

Which would make not only everywhere the center, but everywhere also the edge (of the observable universe).

So my question/confusion comes in, because doesn’t that mean that the universe was that big that long ago?

Or even more, what if (theoretically) you leap frogged the telescopes, and we saw 13 billion light years away (13 billion years into the past) and then put a telescope there pointing in the same direction, and so on?

I feel like I’m making an incorrect assumption somewhere.


A very bright quasar was found to be obscuring hundreds of galaxies.

Quoting from the article:

the quasar’s light is so bright that it has obscured hundreds of galaxies clustered around it.

In their new analysis, the researchers estimate that there are hundreds of individual galaxies in the cluster, which, all told, is about as massive as 690 trillion suns. Our Milky Way galaxy, for comparison, weighs in at around 400 billion solar masses.

The team also calculates that the quasar at the center of the cluster is 46 billion times brighter than the sun.

What does this mean in practice? How far away would you have to be for the light not to be unbearable?


I've looked everywhere and this is driving me crazy, so hopefully someone here can help me.

I'm curious as to why light bends during refraction. I understand that when it travels from one medium to another, its speed changes, which is responsible for the refraction. What I don't understand is why this change in speed causes the light to change directions. Why wouldn't the light just pass through the medium, heading in the same direction, but at a slower (or faster) speed?

Wikipedia gives the following analogy: "Imagine a marching band as it marches at an oblique angle from a pavement (a fast medium) into mud (a slower medium). The marchers on the side that runs into the mud first will slow down first. This causes the whole band to pivot slightly toward the normal (make a smaller angle from the normal)."

In this case, why must light (the marching band) change it's course of motion because of the new angle cause by the slowing down of one side? Why doesn't the light just keep heading straight, but have a weird slant in the front instead of a straight line?

I hope this makes sense, please ask if I need to clarify anything. Thanks for the help in advance.


Manufacturers of these GTLS (gaseous tritium light source) watches love to claim that they are completely harmless because the beta decay of Tritium cannot penetrate intact skin. They never mention the X-ray emission caused by bremsstrahlung - the reaction between the phosphorus and tritium.

Having an always-on low energy x-ray source strapped to your wrist can't be safe... can it?


Assuming the power and technology to actually do it, are there enough gas molecules in the various orbit distances to be collected, compressed, and used as thrust to maintain speed and attitude to continuously hold orbit forever? I know the satellite's orbit and mass would matter a lot, but is it even possible at any scale?


I've read that magnetism in elements like iron - is caused by lone electrons in orbitals that spin in 1 direction and that magnetism is merely the cumulative effect of these electrical charges moving through space with 1 spin.

But according to Hund's rule, the electron configuration of many elements with 4 valence electrons such as Carbon or Silicon also have their outer orbitals filled with electrons spinning in only 1 direction.

So why are elements like Iron magnetic but not elements like Carbon or Silicon?


For so long I have been trying to find explanation to why speed of light is speed limit.

The answers that I get are: "Because time stops" or "You would need infinite energy to reach speed limit" or "You can only reach 99.99% of speed of light", other explanations that are formula-a-like contain constants like Planck length or vacuum permittivity which again contain c. I have been stuck in this loop for a long time and I would be very grateful if someone could explain why speed of light is maximum speed limit give me some directions to some videos for graphical explanation or some literature with some formulas that I could plug in numbers.


For instance, you put alcohol in room temperature 'boiler' and then just run the thing through condenser. Wouldn't the alcohol just vaporize making the distillation happen only slowly?


How do hatchbacks compare with sedans when it comes to induced drag? Which is more aerodynamic, and why?


I would assume that ''strange behaviour in animals'' has been studied for quite a while, but not as psychopathologies.

I tried to do some googling and the earliest book I could find is ''Origins of Madness: Psychopathology in animal life(1979)'' by J.D. Keehn, but I'm not sure if this is the earliest instance of it.

Sorry, I'm not sure if this falls under biology or psychology.

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I spent a weird amount of time the other day observing the color of rain filled clouds, and so I was wondering, why are rainy clouds dark grey, when in fact it’s conformed of water droplets which are transparent. I thought maybe it had to do with the temperature of the water, but hot water is just less clear than cold water, not darker in any way; so, why are those clouds so dark? Is it because of the way it refracts light? I would really love an answer to this question because it truly does intrigue me deeply.


Also, is there any real difference between a helium nucleus and an Alpha particle?


Most questions answer this in terms of conductive material such as aluminum vs. rubber etc. What about air? What about a vacuum?

I recently bought Corona Dope for an electric fence project that was shorting out, and I was wondering wtf that stuff is made of that it stopped the shorts between two contacts that were arcing in just air. Is this material more resistive than air?


I know that animals like horses and cows have different bacteria in their GI tracts due to only eating plants and no meat, which is why their manure can be used as fertilizer. If humans eat a strictly vegan diet long enough, do their GI tracts adjust the bacteria in the same way?


Obviously we can distinguish between hot or cold, but what exact physical quantity do our bodies "measure" or sense? For example, temperature, thermal capacity, heat flux, heat rate, etc.

I don't think we sense temperature, because a metal at room temperature will feel colder than a nonmetal at room temperature.

What thermal quantity do we sense when we touch things?

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By "difficult" I mean requiring an inordinate amount of computation. If given both an encrypted and unencrypted file/message, is it reasonable to be able to recover the password that was used to encrypt the file/message?

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