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

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• AskScience AMA Series: I'm Paul Sutter, astrophysicist, amateur cheese enthusiast, and science advisor for the upcoming film UFO. Ask Me Anything!
• What causes our stomach to rumble when we are hungry?
• What causes the gas pump to stop when your tank is full?
• How are solar activity and galactic cosmic rays correlated?
• what influence does the coriolis effect have at the equator?
• Do mirrors have "focal lengths"?
• Is there another material - synthetic or not - that collects and magnifies light (e.g. telescopes, hand lens) better than glass?
• 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?
• What's the origin of the CMB anisotropy and are quantum fluctuations real or not?
• Do atomic nuclei rotate?
• 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?
• Why can't soundwaves bounce off each other?
• Is it possible to generate visible light by oscillating a permanent magnet?
• Forces acting on 2 free particles in space?
• Are there massive fish deaths whenever there are lightning storms over the ocean?
• What makes central Africa so mineral and jewel rich?
• Is there anything like a 'sound mirror'?
• Does gravity prevent terrestrial planets from gaining larger amounts of mass?
• After seeing this picture of Saturn as taken by Cassini, wondering why, exactly, the pole is shaped like a hexagon?
• 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?
• Is there any evidence of animals getting sore muscles after they exercise too much?
• When you plastically deform an object does its modulus of elasticity remain the same if you stretched it again from its new length?
• How does sweat cool us down if it’s the same temperature as our bodies?

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 [link] [comments]

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 [link] [comments]

What causes the gas pump to stop when your tank is full? Posted: 27 Aug 2018 07:19 PM PDT submitted by /u/PlayfulKatieJ [link] [comments]

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 [link] [comments]

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 [link] [comments]

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 [link] [comments]

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 ​ submitted by /u/skydivingbigfoot [link] [comments]

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 [link] [comments]

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 [link] [comments]

Do atomic nuclei rotate? Posted: 28 Aug 2018 02:58 AM PDT If so, how rapidly? submitted by /u/spauldeagle [link] [comments]

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 submitted by /u/TacosArePeopleToo [link] [comments]

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 [link] [comments]

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 [link] [comments]

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 [link] [comments]

Are there massive fish deaths whenever there are lightning storms over the ocean? Posted: 27 Aug 2018 01:34 PM PDT submitted by /u/CaptainHummus [link] [comments]

What makes central Africa so mineral and jewel rich? Posted: 27 Aug 2018 12:16 PM PDT submitted by /u/Schnitzenium [link] [comments]

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 [link] [comments]

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 [link] [comments]

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 https://www.reddit.com/r/Damnthatsinteresting/comments/9am2dp/amazing_high_resolution_image_of_saturn_taken_by/?utm_source=reddit-android submitted by /u/DeusIncognito [link] [comments]

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 submitted by /u/atoteca [link] [comments]

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 [link] [comments]

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 submitted by /u/Y-Woo [link] [comments]

How does sweat cool us down if it’s the same temperature as our bodies? Posted: 27 Aug 2018 06:37 PM PDT submitted by /u/MissionCow [link] [comments]

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