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Wednesday, August 29, 2018

What are the technological hurdles that need to be overcome in order to create a rotating space station that simulates gravity?

What are the technological hurdles that need to be overcome in order to create a rotating space station that simulates gravity?

What are the technological hurdles that need to be overcome in order to create a rotating space station that simulates gravity?

Posted: 29 Aug 2018 03:10 AM PDT

I understand that our launch systems can only put so much mass into orbit, and it has to fit into the payload fairing. And looking side-to-side could be disorientating if you're standing on the inside of a spinning ring. But why hasn't any space agency even tried to do this?

submitted by /u/PhyrexianOilLobbyist
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Why isn't atmospheric CO immediately oxidised to CO2 by oxygen in the air?

Posted: 29 Aug 2018 05:50 AM PDT

Is oxygen just not a powerful enough oxidising agent?

submitted by /u/SpaceSpheres108
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If you were traveling forward as fast as a bullet, what would happen if you shot a bullet towards the direction you were heading?

Posted: 28 Aug 2018 11:01 PM PDT

Does Hawking Radiation violate Baryon Number conservation?

Posted: 28 Aug 2018 08:17 AM PDT

Since Hawking Radiation doesn't consider the types of particles that entered the black holes, doesn't that mean at some point baryon number conservation is violated?

Since Hawking Radiation is an explanation of quantum effects, shouldn't it be in agreement with current quantum theory?

As far as I know Hawking Radiation and Baryon Number Conservation are both generally accepted, but how can they be reconciled?

submitted by /u/Anaklusmos
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Ask Anything Wednesday - Engineering, Mathematics, Computer Science

Posted: 29 Aug 2018 08:12 AM PDT

Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Engineering, Mathematics, Computer Science

Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical /r/AskScience post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...".

Asking Questions:

Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions.

The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit /r/AskScienceDiscussion , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists.

Answering Questions:

Please only answer a posted question if you are an expert in the field. The full guidelines for posting responses in AskScience can be found here. In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for /r/AskScience.

If you would like to become a member of the AskScience panel, please refer to the information provided here.

Past AskAnythingWednesday posts can be found here.

Ask away!

submitted by /u/AutoModerator
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How can the speed of light be constant?

Posted: 29 Aug 2018 06:57 AM PDT

Sorry, this is just a collection of thought, and I dont have any hard facts to back me up, but I have thought a lot about it.

The speed of light is constant and is used in a few equations such as E=MC2. My ultimate question is that if speed is relative then would physics change at near light speed?

If you are in a car moving 10 m/s north, and you pass another car moving at 9 m/s then relative to you the car is moving at 1m/s south. So by the same logic if you are standing on earth looking at a star, and rocket were to speed towards that star at 1000 m/s then to the person on earth the light is moving at the speed of light. However to space ship moving directly towards the star the light would be moving at the speed of light plus 1000 m/s, the speed of the ship.

If there is something in there that is logically unsound then here is another example.

Speed is defined as distance traveled over time. However, as you approach the speed of light time and distance dilate. Due to this dilation we can assume that time and space are relative, and as such speed (which time and space make up) is also relative.

Do I have some form of a misunderstanding? If speed is relative then we can assume that the speed of light is relative. If that universal constant isn't constant relative to another position then would physics act differently where that speed is different?

Again, sorry about how this might have not made much sense. I am not sure how to explain it better.

submitted by /u/sontath
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Alternatives to the Linde-Process for producing nitrogen?

Posted: 28 Aug 2018 02:33 PM PDT

I know about the Linde-Process but are there any other (cheeper) processes to get pure nitrogen out of the air and how do they work (industrial not lab. scale)?

I can't find much in the internet about the membran-process. How does it work and do you know good sources?

Thanks for your answer!

submitted by /u/druef99
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Do the Strong and Weak Forces have a field like Gravitation and EM?

Posted: 28 Aug 2018 09:43 AM PDT

Can anyone point me to an explanation of the greenhouse effect written by a physicist?

Posted: 28 Aug 2018 09:28 AM PDT

This is a crosspost from askphysics, but since they're a fairly small sub, I was hoping it would be ok to share it here.

https://www.reddit.com/r/AskPhysics/comments/9b06wd/physics_of_greenhouse_effect/

I'm having difficulty understanding how greenhouse gases (GG) "trap" infrared radiation (IR). As I understand it, carbon dioxide (CO2) absorbs IR in a few narrow bands of wavelengths (4.3 and 15 micrometers). A CO2 molecule that absorbs a photon will vibrate until it can emit a photon of its own.

A few questions for those of you who've studied thermodynamics;

  • do GG's increase global temps via vibration, or emission?

  • if vibration, how long is the time between absorption and emission?

  • if emission, do emitted photons leave a molecule in a consistent direction, or are their vectors completely random?

  • do the absorbed and emitted photons have identical wavelengths?

Thanks to all who take the time to help explain...

submitted by /u/adoomedman
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What actually happens to a Guitar string on a physical level that results in a different note playing after being tightened?

Posted: 28 Aug 2018 09:23 PM PDT

How many vertebrates are there on earth?

Posted: 28 Aug 2018 09:04 AM PDT

I'm trying to find an estimate of the total number of vertebrate animals on earth--not species, but population of individual vertebrates.

I can only find various sources (1,2) that estimate subsets of vertebrates (for instance, livestock chickens is estimated to be 19.6 billion alone)3, and many more that get into individual subsets, but I'm hoping to find something that estimates all vertebrates from lower chordates to primates.

Sources:

1 https://en.wikipedia.org/wiki/Lists_of_organisms_by_population

2 https://www.npr.org/sections/thetwo-way/2011/11/03/141946751/along-with-humans-who-else-is-in-the-7-billion-club

3 https://www.fastcompany.com/3031945/a-massive-global-map-of-where-all-the-cattle-pigs-and-other-livestock-live

submitted by /u/fidler
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As gamma waves became CMB, at what rough time in the Universe's history did they red shift through visible light?

Posted: 28 Aug 2018 07:40 AM PDT

This has bugged me for years. I am perfectly content with CMB as evidence for the big bang and all that, but, given that gamma waves were simply shifted down into longer wavelengths, this raises the implication that at some point, everywhere you looked, it would have been violet. Then indigo, then blue, etc.

Do we have any idea when this might have happened in the Universe's history? Even approximately?

submitted by /u/Perigeesus
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How does airplanes and helicopters behave with respect of Earth once they take off?

Posted: 28 Aug 2018 01:10 PM PDT

I can't wrap my head around how a flying object, like an airplane or helicopter, behave once in flight with respect of the Earth. Let me explain: consider a flight from Frankfurt to Capetown, almost straight north-south route: does the plane flight in a straight north-south line or does it need to "correct" because the earth is actually "escaping" under it, thus flying in an oblique line from the initial point of view? Does it "feel" earth rotation? Does it need to point towards the position of Capetown at the time of take-off or at the time of landing?

Similarly, if an helicopter simply takes off and stays up indefinitely, does it stays over the same point? I expect the answer being yes; in this case, is it due to some sort of drag from the atmosphere or because helicopter and earth are actually in the same system and are tied together?

Sorry for: question being eventually stupid, me being a little drunk and English not being my language.

submitted by /u/tekanet
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Why was the transistor such an important breakthrough?

Posted: 28 Aug 2018 02:20 PM PDT

What makes it a necessary part of computers and how does it work?

submitted by /u/DefaultPlayer99
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What is healthier for the phone battery?

Posted: 28 Aug 2018 10:33 AM PDT

Don't know where to ask it, so might as well put it here.

Lets say my smartphone needs to be constantly connected for a long period of time to the computer, even though the battery is already full. In this case what would be better in preserving the battery in the long run, leaving the screen turned on or off? Is there even a difference?

submitted by /u/PinkiePieYay2707
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Tuesday, August 28, 2018

AskScience AMA Series: I'm Paul Sutter, astrophysicist, amateur cheese enthusiast, and science advisor for the upcoming film UFO. Ask Me Anything!

AskScience AMA Series: I'm Paul Sutter, astrophysicist, amateur cheese enthusiast, and science advisor for the upcoming film UFO. Ask Me Anything!

AskScience AMA Series: I'm Paul Sutter, astrophysicist, amateur cheese enthusiast, and science advisor for the upcoming film UFO. Ask Me Anything!

Posted: 28 Aug 2018 04:01 AM PDT

Hey reddit!

I'm Paul Sutter, an astrophysicist and science advisor for the film UFO, starring Gillian Anderson, David Strathairn, Alex Sharp, and Ella Purnell. I am not nearly as beautiful as any of those people, which is why I'm here typing to you about science.

The film is about a college kid who is convinced he's recorded an alien signal. I helped writer/director Ryan Eslinger, plus the cast and crew, make sure the science made sense. And considering such topics as the Drake Equation, the fine-structure constant, 21cm radiation, and linear algebra are all (uncredited) costars in the movie, it was a real blast.

I also briefly appear in one scene. I had lines but they didn't make the final cut, which I'm not bitter about at all.

Besides my research at The Ohio State University, I'm also the chief scientist at COSI Science Center here in dazzlingly midwestern Columbus, Ohio. I host the "Ask a Spaceman!" podcast and YouTube series, and I'm the author of the forthcoming Your Place in the Universe (which is like Cosmos but sarcastic and not a TV show). I do a bunch of other livestreams, science+art productions, and TV appearances, too. I also consult for movies, I guess.

I'll be on from 2-4pm ET (19-21 UT), so AMA about the science of UFO, the science of the universe, and/or relationship advice. As I tell my students: my door is always open, except when it's closed.

submitted by /u/AskScienceModerator
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What causes our stomach to rumble when we are hungry?

Posted: 27 Aug 2018 08:02 AM PDT

I understand that it means we are hungry but why does it rumble? My 10 second rumble made me question it

submitted by /u/PeterP1227
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What causes the gas pump to stop when your tank is full?

Posted: 27 Aug 2018 07:19 PM PDT

How are solar activity and galactic cosmic rays correlated?

Posted: 28 Aug 2018 05:21 AM PDT

I'm reading a book on space environment and I came across an interesting fact:

"The GCR flux is seen to be dependent on the solar cycle, with GCR rate being highest at solar minimum."

But no explanation as to why. Does anyone know why this happens?

Book in question is Alan C. Tribble The Space Environment Implications for Spacecraft Design Princeton: Princeton University Press, 2003. Print

submitted by /u/Vetalurg
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what influence does the coriolis effect have at the equator?

Posted: 27 Aug 2018 10:50 PM PDT

http://www.hisiasafaris.com/en/blog/safaris/equator-and-coriolis-effect-kenya

I was doing some reading and came across this article which claims that a match placed in water will have different effects based on where you are standing in relation to the equator.

on the equator the match will not move.

to the south and the match will spin to the left

to the north and the match spins to the right.

1) is it correct to attribute this spinning to the coriolis effect or is it something else

2) the match isn't magnetic so this isn't related to the poles so what is making the match spin?

submitted by /u/armored-dinnerjacket
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Do mirrors have "focal lengths"?

Posted: 28 Aug 2018 06:28 AM PDT

I don't know how to put it better than asking if mirrors also can have different "focal lengths" like lenses – in some mirrors my face looks a bit wider, as if the mirror was a bit more wide angled, and sometimes it looks a bit narrower, as if my face was seen through a tele lens.

submitted by /u/Benniisan
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Is there another material - synthetic or not - that collects and magnifies light (e.g. telescopes, hand lens) better than glass?

Posted: 28 Aug 2018 06:46 AM PDT

What would happen if two people, tied together by a rope, were falling, and the lower of the two people started pulling on the rope? Would the lower person fall slower, the higher faster, or neither?

Posted: 28 Aug 2018 06:33 AM PDT

I've never taken a physics course before, so I simply don't have the background here to understand this. Logically, I would think that the lower person would briefly fall slower, the higher person would briefly fall faster, and the two would end up somewhere near the middle of the distance that was between them prior to the lower person pulling on the rope.

submitted by /u/Quixel
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What's the origin of the CMB anisotropy and are quantum fluctuations real or not?

Posted: 28 Aug 2018 05:42 AM PDT

Recently I've heard from various sources that virtual particles, vacuum fluctuations, quantum fluctuations, whatever you want to call them, are not real things and are merely mathematical tools; internal lines in Feynman diagrams and a perturbation expansion series. For example, this article makes the following statements (emphasis mine):

On vacuum fluctuations:

Thus the presence of a Gaussian distribution means that the value of the electromagnetic field in the vacuum state is not determined with arbitrary precision but has an inherent uncertainty. No temporal or spatial implications can be deduced. (The distribution itself is independent of time and space.) Thus it is misleading to interpret vacuum fluctuations as fluctuations in the common sense of the word, which is the traditional name for random changes in space and time. The vacuum is isotropic (i.e., uniform) in space and time and does not change at all.

On vacuum diagrams:

As a consequence, vacuum diagrams have no physical interpretation; in particular, they do not enter the formulas for vacuum expectation values (and hence vacuum fluctuations). The name comes from the form in which these diagrams are conventionally drawn, and doesn't point to anything bubbling in the vacuum.

In general:

In the following, I give precise definitions of many terms, telling what they really mean as part of the technical language used in quantum field theory. They have meaning only in this precisely defined context, and are meaningless otherwise. For example, virtual particles have a technical meaning in a discussion of Feynman diagrams, but not in stories where they are claimed to pop in and out of existence. Similarly, vacuum fluctuations have a technical meaning in a discussion of certain vacuum expectation values, but not in stories where they are claimed to describe a sizzling vacuum, or to cause a physical effect.

Ok, so everything I've read about space-time foam and fluctuations in fields is wrong, but then what's actually going on? And why is stuff like Quantum Fluctuations and Their Energy and The Quantum Origin of Large-Scale Structure out there? What's behind the anisotropy of the CMB if quantum fluctuations aren't real?

In The Quantum Origin of Large-Scale Structure, chapter 2 is titled Quantum Fluctuations during Inflation and starts off with the following:

In this chapter and the next, we discuss the primordial origin of the temperature variations in the CMB. The main goal will be to show how quantum fluctuations in quasi-de Sitter space produce a spectrum of fluctuations that accurately matches the observations. The reason why inflation inevitably produces fluctuations is simple: as we have seen in the pre- vious chapter, the inflaton evolution φ ( t ) governs the energy density of the early universe ρ ( t ) and hence controls the end of inflation. Essentially, φ plays the role of a local clock reading off the amount of inflationary expansion remaining. Because microscopic clocks are quantum- mechanical objects with necessarily some variance (by the uncertainty principle), the inflaton will have spatially varying fluctuations δφ ( t, x ) ≡ φ ( t, x ) − ̄ φ ( t ). These fluctuations imply that different regions of space inflate by different amounts. In other words, there will be local differ- ences in the time when inflation end δt ( x ). Moreover, these differences in the local expansion histories lead to differences in the local densities after inflation. In quantum theory, local fluctua- tions in δρ ( t, x ) and hence ultimately in the CMB temperature ∆ T ( x ) are therefore unavoidable. The main purpose of this chapter is to compute this effect. It is worth remarking that the the- ory wasn't engineered to produce the CMB fluctuations, but their origin is instead a natural consequence of treating inflation quantum mechanically.

So on the one hand, we have people saying that the vacuum is static and eternal and absolutely does not undergo fluctuations in time and space and that's all just a bunch of pop-sci rubbish the public has been misled with, and other people saying that it fluctuates in time and space and we can even see these fluctuations because inflation expanded microscopic quantum fluctuations to cosmological scales and that's the origin of the tiny temperature fluctuations observed in the CMB and why it looks like this and why it has this power spectrum.

And then to confuse matters further there's stuff like this claiming to be a simulation of the gluon field in the QCD vacuum in a volume of space of 2.4 by 2.4 by 3.6 fm.

And then there's this paper by Qingdi Wang, Zhen Zhu and William G. Unruh titled How the huge energy of quantum vacuum gravitates to drive the slow accelerating expansion of the Universe that says the following:

Thus the energy density fluctuates as violently as its own magnitude. With such huge fluctuations, the vacuum energy density ρ vac is not a constant in space or time. Furthermore, the energy density of the vacuum is not only not a constant in time at a fixed spatial point, it also varies from place to place. In other words, the en- ergy density of vacuum is varying wildly at every spatial point and the variation is not in phase for different spatial two spacial points quickly goes up to the order of 〈 T 00 〉 itself as their distance increases by only the order of 1 / Λ. (For more details on the calculations and how the energy density fluctuates all over the spacetime, see Appendix A.) As the vacuum is clearly not homogeneous, equa- tion (10) is not valid as it depends on a homogeneous and isotropic matter field and metric. Therefore a new method of relating vacuum energy density to the ob- served Hubble expansion rate is required.

Can anyone please help clear up my massive confusion on this topic? I've no idea who to believe at this point and it just feels like people are talking about very different things without making it clear they're talking about different things, that physicists are abominably bad at explaining things, or that there's some deep and fundamental divide in the field of physics that I wasn't previously aware of.

submitted by /u/Peter5930
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Do atomic nuclei rotate?

Posted: 28 Aug 2018 02:58 AM PDT

If so, how rapidly?

submitted by /u/spauldeagle
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What measurable effects has the Panama Canal had on the ecosystem around it? Between migratory routes, aquatic wildlife moving from one body of water to the other, etc?

Posted: 27 Aug 2018 12:19 PM PDT

Why can't soundwaves bounce off each other?

Posted: 27 Aug 2018 05:06 PM PDT

If sound is made of molecules moving to create a pressure wave, is it not reasonable to assume some air molecules of opposing wavefronts will

1) Collide with each other and bounce off instead of propagating their respective wave.

2) Pass by each other without interacting and creating the next wave after colliding with the molecules behind the ones they just missed? Could this help explain superposition? The wave "bypassed the barrier" and made a wave behind it.

submitted by /u/yosimba2000
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Is it possible to generate visible light by oscillating a permanent magnet?

Posted: 27 Aug 2018 04:11 PM PDT

As the title says, if I where to theoretically spin or otherwise oscillate a permanent magnet at a very very high frequency (for example 500 THz), could visible light be generated? Would enough light be created to detect with the naked eye? Is this something that could realistically be constructed?

submitted by /u/fogh1
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Forces acting on 2 free particles in space?

Posted: 28 Aug 2018 05:29 AM PDT

If two charged particles are in space, do only two forces exist between them; electrostatic force and gravitational force? Suppose they are oppositely charged, then will they be attracted (due to G force) or repelled (due to electrostatic force)?

submitted by /u/FluffyCat10
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Are there massive fish deaths whenever there are lightning storms over the ocean?

Posted: 27 Aug 2018 01:34 PM PDT

What makes central Africa so mineral and jewel rich?

Posted: 27 Aug 2018 12:16 PM PDT

Is there anything like a 'sound mirror'?

Posted: 27 Aug 2018 10:43 PM PDT

I was thinking that since mirrors reflect light waves, there could be an equivalent to reflect sound waves.

I hope this is not a stupid question and the answer is not too obvious that I'm ignoring it.

submitted by /u/clumsy_cactus
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Does gravity prevent terrestrial planets from gaining larger amounts of mass?

Posted: 27 Aug 2018 07:11 PM PDT

I was researching the largest stars in the universe. Presumably, those stars also have solar systems. What would those planets look like? Could we just scale up our solar system to match with the larger star?

submitted by /u/ForcedRonin
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After seeing this picture of Saturn as taken by Cassini, wondering why, exactly, the pole is shaped like a hexagon?

Posted: 27 Aug 2018 02:20 PM PDT

If it's impossible for noble gasses to react to other elements. Then how does helium and hydrogen create high energy astronomical objects like the sun?

Posted: 27 Aug 2018 08:19 PM PDT

Is there any evidence of animals getting sore muscles after they exercise too much?

Posted: 27 Aug 2018 06:41 PM PDT

I have a generally lazy house cat, but I just got him a toy that he's been going nuts for. Running/jumping all over the place. I know if I'd gone from mostly sedentary to this amount of exercise, I would be sore the next day. Wondering if there any evidence of animals experiencing a similar feeling?

submitted by /u/christz9
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When you plastically deform an object does its modulus of elasticity remain the same if you stretched it again from its new length?

Posted: 27 Aug 2018 10:45 AM PDT

How does sweat cool us down if it’s the same temperature as our bodies?

Posted: 27 Aug 2018 06:37 PM PDT
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Monday, August 27, 2018

Do satellites, like the Hubble Telescope, get dirty?

Do satellites, like the Hubble Telescope, get dirty?

Do satellites, like the Hubble Telescope, get dirty?

Posted: 26 Aug 2018 09:49 AM PDT

I just saw a question asking about the remaining lifespan of the Hubble Space Telescope, and I was wondering if there is anything in space that causes satellites to get dirty, or rust, or otherwise deteriorate.

submitted by /u/Raiderboy105
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Are rates depression and anxiety on the rise (and if so, why)? Or are we just diagnosing it more because we’re more aware of it?

Posted: 26 Aug 2018 07:14 PM PDT

Why are tsunamis wave heights measured/described as being much taller than they actually seem to be?

Posted: 26 Aug 2018 08:36 PM PDT

What I mean is, for example, the 2011 Tohoku earthquake and tsunami in Japan. The tsunami had waves of up to 40.5m (133ft). That's just a little bit taller than the statue of liberty. But when I watch videos and clips of the tsunami making landfall, it doesn't seem anywhere near 40.5m tall. I literally imagine a wall of water the size of the statue of liberty when it's described like this (kinda like in the movies).

So how are tsumani wave heights actually measured?

submitted by /u/TheOneWithTheOne
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How high can insects fly? And why would they do it?

Posted: 26 Aug 2018 12:53 PM PDT

How do we calculate distances to celestial bodies?

Posted: 26 Aug 2018 01:26 PM PDT

How do we know that Andromeda is 2.5 million light years away? Is there any way we can tell that the light we are getting from Andromeda is 2.5 million years old?

Edit: I used Andromeda as just an example.

submitted by /u/Deat_h
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Are seemingly sealed surfaces also completely sealed at the molecular level, or do they leak?

Posted: 26 Aug 2018 12:32 PM PDT

For example, in a water bottle that is completely closed and sealed, do the walls leak water molecules at the microscopic level? Do molecules or atoms inside a container slowly get through the cracks between bonds of the container's material?

submitted by /u/PsychohistorySeldon
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How is RISC-V different from normal RISC?

Posted: 27 Aug 2018 01:39 AM PDT

I've heard that RISC-V is a open source architecture, how exactly is it open source and what are its benefits? How small is the processor and how small can it get? What is the performance like? Is it a big deal for general computing?

submitted by /u/socialmachan2
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Exactly how do you hook up new organs in the body to the blood vessels during a transplant?

Posted: 26 Aug 2018 03:04 PM PDT

Questions says it all. In cars if you replace the engine you have to also reconnect the wiring harness etc. How does this work with organs?

submitted by /u/IrohtheTeaBender
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How would a moon with a more elliptical orbit impact life on Earth?

Posted: 26 Aug 2018 12:01 PM PDT

What impacts would the moon having a significantly more elliptical orbit (similar to Pluto's) have on the rotation of the Earth, phases and tides?

submitted by /u/Pentastome
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How does a vine searching for and object to climb “know” not to wrap around itself?

Posted: 26 Aug 2018 10:20 AM PDT

I've seen a time laps video of a climbing vine and as it circles around searching for something to climb it seems to run into a chute from itself. Upon interacting with itself it simply disengages and continues its search for another object.

How does it recognize itself?

submitted by /u/Stellar1616
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Why do acids tend to be corrosive?

Posted: 26 Aug 2018 11:52 AM PDT

How does a computer actually 'turn on'?

Posted: 26 Aug 2018 08:33 AM PDT

I have seen things online, but they're all incomplete or outdated.

submitted by /u/riggycat
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Why is an object's temperature and black-body emitted radiation related by a power of four?

Posted: 26 Aug 2018 01:33 PM PDT

I've been getting into the fundamentals of satellite remote sensing and I have a question motivated out of pure curiosity. The Stefan–Boltzmann law describes that the amount of radiation an object emits is related to it's temperature. A small change in temperature, T, causes a huge change in radiation, M = k*T^4, where k is a constant. My question is, where does this fourth power come from? Is it related to Rayleigh scattering being inversely proportional to the inverse of the fourth power of radiation wavelength?

submitted by /u/gizable
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Can wild type insects make mistakes?

Posted: 26 Aug 2018 10:54 AM PDT

How tied to instincts are they? Do they sometimes do things that they shouldn't do according to instict, assuming there are no abnormal parameters? If you filmed an ant for a few weeks, would it sometimes trip over its own legs? (failure in hunt excluded from this question)

submitted by /u/fruitpunch-alien
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Why don’t the rings of Saturn and other big planets get pulled into the core by their massive gravitational force?

Posted: 26 Aug 2018 08:50 AM PDT

Is it possible to predict the appearance of a substance/material based on a few of its atoms?

Posted: 26 Aug 2018 05:42 PM PDT

For example, does an Aluminium atom appear to be silver and shiny? I'm assuming it all goes down to how a group of the bonded atoms are able to reflect and absorb visible light, but is there any way to predict it? If so, what would a Synthetic atom, say Oganesson 118, look like?

submitted by /u/ZeligD
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[Semiconductor] With Gallium being a popular compound semiconductor material for various electronic device applications, how come Gallium Oxide has only very recently (within the last year) garnered the attention of scientists as a prospective material for future electronics?

Posted: 26 Aug 2018 12:13 PM PDT

Gallium Arsenide and Gallium Nitride are commonly used compound semiconductors that have been of interest for a few decades. How come scientists didn't think to use Gallium Oxide until just recently? All you would have to do is just oxidize Gallium to make Gallium Oxide.

Now I understand in reality, it isn't as simple as Silicon oxidation, since a process like thermal oxidation will result in an amorphous oxide. So if thermal oxide is used to grow Gallium Oxide (amorphous), can that only serve as a dielectric? Is it a mandatory requirement that Gallium Oxide has to be in the crystalline form to act as a semiconductor? (I assume yes, because a crystalline structure is required for conductive paths for electrons/holes to flow.)

So then what was the breakthrough that brought scientists their attention to Gallium Oxide? Was it just that scientists finally figured out (maybe by accident?) how to grow Gallium Oxide in crystalline form?

If that was indeed the breakthrough, then should we expect research going into the growth of crystalline Silicon Oxide? (If crystalline Ga2O3 is possible, why not crystalline SiO2?)

​

​

submitted by /u/spacejockey8
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Does Space Debris affect the ISS?

Posted: 26 Aug 2018 10:23 AM PDT

Recently saw that there are roughly 15,000 pieces of space debris orbiting Earth. I know they pose threats for various satellites, but do they pose any threat to the International Space Station, and if so, how does the ISS avoid it?

submitted by /u/pdnaylor
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Why use the ideal gas constant in aqueous solution electrochemistry?

Posted: 26 Aug 2018 08:22 AM PDT

Why is the ideal gas constant (R = 8.3145 J/mol•K) used in the Nernst equation and Nernst-Planck equation when working out the electrochemistry of aqueous solutions, when aqueous solutions are not gases and rarely ideal?

submitted by /u/qaaqqaaq
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