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Tuesday, December 3, 2019

Can you cross the beams of a uv laser and an infrared laser to make visible light?

Can you cross the beams of a uv laser and an infrared laser to make visible light?

Can you cross the beams of a uv laser and an infrared laser to make visible light?

Posted: 02 Dec 2019 09:09 PM PST

The underlying reason I was thinking about this is that I vaguely recall when I was taking an acoustics class in college that there was a concept of two soundwaves of different frequencies overlapping and creating another frequency. I am likely getting that part wrong, but whatever the concept was it made me wonder if the same could be true for light.

submitted by /u/SKRuBAUL
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Is there any molecules is space? I mean in the vacuum part of the space?

Posted: 03 Dec 2019 03:52 AM PST

I've learnt that there's absolutely nothing between us and the moon or basically anything till we reach their atmosphere and I'll be honest I just came up with this question out of the blue right now but I am curious, is there really nothing in space?

submitted by /u/sugondese_beh
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Can a sha512/md5 hash be reverse engineered that it can produce the original file?

Posted: 03 Dec 2019 05:44 AM PST

Sand that’s beneath the sand at the deepest part of the ocean - is it wet too or is it dry due to some kind of intense pressure barrier?

Posted: 02 Dec 2019 10:33 PM PST

Is 'dopamine fasting' legit? What's the science behind it?

Posted: 03 Dec 2019 04:26 AM PST

"Proponents of dopamine fasting believe that we have become overstimulated by quick 'hits' of dopamine from things like social media, technology and food. They say that by deliberately avoiding these common stimulants – which we see as pleasurable activities – we can decrease the amount of dopamine in our brain. Then, after the fast, when we re-engage with these stimulants, we enjoy them more and our lives feel better."

submitted by /u/chernya
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With the power of interferometry and the like, is there still any advantage to constructing extremely large single-dish radio telescopes?

Posted: 02 Dec 2019 11:14 PM PST

Science Discussion Series: We are a panel of scientists working on the biology of music and language, here to chat with you about how our brains accomplish the amazing feat of communicating through speech and music! Let’s discuss.

Posted: 03 Dec 2019 08:03 AM PST

Can anyone explain nuclear reactor breeding ratios? And a few other questions.

Posted: 03 Dec 2019 03:05 AM PST

I'm currently working on a mod for a video game (Factorio) which overhauls how nuclear energy in the game works. Partly I'm doing this because the game makers saw fit to make solar power seem like a better option for power at scale, and partly because if I end up being able to get people interested in nuclear energy, then all the better. I want to teach with my mod, but teach to a crowd that is mildly curious and utterly ignorant, so I am starting them off with crayons instead of 3d modeling software.

I've hit something of an understanding wall, where my google-fu and existing knowledge are insufficient to get me over the next hurdle of understanding. My mod is designed to have 3 reactors available for use by the player:

Tier 1: 500MWe (2GWth) LWR. Assume this is one of the very first gen I light water reactors. Inefficient, not many best practices or improvements. Only 25% efficient overall. Huge material cost due to vast amounts of concrete and steel needed to construct the pressure/biological safeties.

Tier 2: 1GWe, 33% overall plant efficiency. This is to be either a Gen III+ or IV sodium fast reactor design. Because of how the game works, much of the beauty of it being a breeder reactor design will have to be moved from the reactor core itself to the fuel reprocessing cycle. I assume oxide or metal fuel. Fundamentally, it doesn't seem like sodium fuel rods are that different from LWR rods, apart from the specifics of engineering them (material choices, shape, pins instead of pellets, separating u235/pu239 from u238 so that you get better breeding, etc).

Tier 3: 1.5GWe, 45% overall efficiency. This is meant to be a thorium fueled molten salt reactor (no I don't think it's the godsend some people think, but I do think it's a decent idea worth exploring, I eagerly await results from China and India). Two-fluid design such that it gets a breeding ratio > 1. This reactor will be the first (in the game) to use a high-temp gas for the turbine loop instead of steam. It will also feature an online fuel reprocessing facility built into the reactor site itself.

I have tier 1 pretty locked down. Documentation about how LWRs work is widely available, even to noobs like me. Tiers 2 and 3 are where I hit a few brick walls. With that, here is my wall of questions. You can pick and choose, answer them a few at at time, however you prefer. I just do better if I list everything I don't know because you can possibly save yourself a lot of time, or point out something I'm not considering. Note: None of these reactors are meant to generate anything but power. No weapons proliferation considerations.

  • In a thermal reactor, U238 seems to release around 1.68 TJ/Kg, and U235 seems to be closer to 80 TJ/Kg. Are these numbers sane / close?

  • In a fast reactor, U238 seems to release around 80.6TJ/Kg, and U235 releases around 79.6TJ/Kg. Sane numbers? For both thermal and fast, I'm happy with a sum energy output of the entire fuel cycle, rather than the energy for just the initial isotope fission.

  • I need some help wrapping my head around how best to represent breeding ratios. If I have a breeding ratio of 1.3, then I generate 30% more Pu239 (assuming u238 is what's being bred) than I burn. But...where does that go? When does it get burned? It's not as though the Pu239 that gets bred magically contains 30% more energy. And, it's not as though the reactor suddenly goes prompt critical because too much Pu239 gets bred (I assume this can happen, but operators and engineers work hard to ensure it doesn't!) Do I represent this with a higher fuel burnup rate between refueling? I'm really scratching my head on what to do with this one.

  • On the topic of burnup rates, it seems like 3% is a decent rate for LWR (sort of a median rate), 15% is decent for sodium fast reactors (upper end of the range), but I can't find anything for molten salt reactors. Some places claim 100% burnup, but that's impossible even with online reprocessing. I assumed 80%, but do you know a better number? Are my LWR/Sodium reactor numbers sane/in the right ballpark?

  • Similar to the breeding ratio above, does the burnup number already factor in any breeding ratio? If so...I haven't done calculus in a decade. I'm not up to solving the differential equation(s) for the relation between burnup and breeding ratio (if there is one). Is there an approximation that would be 'good enough' rather than precise? (think newtonian physics vs general relativity)

  • How much fuel (mass) is loaded in a typical LMR and MSR? I can't seem to find any data. The nearest ton, or even 10-tons would be fine. I try to scale the recipes in-game to take a reasonable amount of material. I can't find any data like I can with LWRs.

Thanks for your time and consideration.

submitted by /u/mytwentythredditid
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In strong nuclear force interactions, is there attraction or repulsion between a color and the anti-particle of another color?

Posted: 02 Dec 2019 02:27 PM PST

So, say a red quark and an anti-blue quark. Or a green quark and an anti-red. Would there be attraction or repulsion? Or no force at all?

submitted by /u/donovanBast
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How can you tell composition of minerals?

Posted: 02 Dec 2019 10:15 PM PST

How do people identify minerals just by looking at certain rocks or knowing their source? I guess that comes with experience but do we have a resource where one can reference stuff that they find in natural world to figure out their composition?

submitted by /u/NonElectricalNemesis
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If we found an organism claimed to be an alien, what would be the biological markers we could check to verify it is extraterrestrial, as opposed to a hitherto unknown terrestrial species?

Posted: 02 Dec 2019 06:13 AM PST

Why does Neurofibromatosis type 1 (NF1) only affect the nervous system and the skin (both deriving from the ectoderm)?

Posted: 03 Dec 2019 01:20 AM PST

Neurofibromin 1 is a protein encoded by the the tumor suppressor gene NF1 which negatively regulates the activity of Ras. Mutation of this gene are associated with type 1 Neurofibromatosis, an autosomal dominant disease. By controlling the expression of neurofibromin 1 protein in the various tissues no particular discrepancies are observed: the neurofibromin 1 protein is expressed approximately on the same quantity in all tissues. Whereas Neurofibromatosis type 1 causes problems such as coffee-milk spots, Lisch's iris nodules, freckles and multiple neurofibromas, how is it possible that only nervous system and the skin are affected?

I tried to consult the scientific literature about it not finding the answer to this question. If someone had the answer could you please also send me the link where it is explained?

submitted by /u/coledoco
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Since the Earths orbit is elliptical shouldnt the seasons be slightly shorter or longer?

Posted: 02 Dec 2019 11:25 PM PST

Does the elliptical orbit cause a sort of "slingshot" effect that increases acceleration? I've noticed that spring and fall seem to last a bit longer but that could be due to geographical location (Massachusetts)

submitted by /u/lilyungxrist
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Why doesn't the proton in a hydrogen atom have energy levels like the electron does, or does it?

Posted: 02 Dec 2019 07:39 PM PST

I recently learned about the 3D solution to the Schrodinger equation for hydrogen and it was all focused on the electron. The proton experiences the same potential so it seems like it would have the same solution but with a different mass and radii (distance to the barycenter of the atom?).

submitted by /u/LittleJohnnyNations
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Why do Mercury and Venus spin slowly, but not the Earth?

Posted: 02 Dec 2019 09:38 PM PST

So, Mercury and Venus have long days and short years because they're close to the sun.

Why don't we have a similarly long day? Or even, why did the ratio of day to year jump to drastically?

submitted by /u/Ormith
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I have a cube of copper with a wire coming out of both sides. If I connect the cube to a source of power, what pattern would the electrons make in the cube as it flowed across?

Posted: 02 Dec 2019 05:17 PM PST

Is the y male chromosome dominant over x or are they codominant?

Posted: 02 Dec 2019 09:54 AM PST

Does Inverse Compton-Scattering result in reflection and refraction?

Posted: 02 Dec 2019 08:05 PM PST

While thinking about what happens during reflection/refraction I've come across Fermat's principle then Hugyen's principle and some papers. It appears to me that reflection and inverse compton scattering are the same thing. Is this true?

submitted by /u/actinotroch
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What causes the delay in between contamination by ionizing radiation and the severe symptoms?

Posted: 02 Dec 2019 07:13 PM PST

I was reading about the effects of radiation after rewatching the Chernobyl HBO series was wondering why is there a latency period where you seem fine before the harsher symptoms settle. Couldn't find any satisfactory explanation while searching. Was hoping you could help.

Sorry if this is the wrong flair, wasn't sure which to use...

submitted by /u/JackMcSnek
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Why do stars expand?

Posted: 02 Dec 2019 08:11 AM PST

So the way I understand it, the size of a star is stable due to an equilibrium between gravity pulling matter in, and nuclear fusion pushing matter out.

I'd like to know:

1) How/why does the star switch fuel source to Helium (when it wasn't being fused before)?

2) Why does this transition result in the star expanding?

3) How is this new process maintained after the expansion, stabilizing into a new steady state of Helium consumption (specifically, how is it stable at a larger radius)?

Also, i feel if i could see a free energy diagram for Hydrogen/ Helium fusions, that'd go a long way to help the explanation. So bonus פpoints if you can link em!

submitted by /u/SymphoDeProggy
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Monday, December 2, 2019

Do ants that get lost(accidentally get on my backpack) get adopted by local colonies?

Do ants that get lost(accidentally get on my backpack) get adopted by local colonies?

Do ants that get lost(accidentally get on my backpack) get adopted by local colonies?

Posted: 02 Dec 2019 02:13 AM PST

What part of your brain gets activated when you "talk to yourself"?

Posted: 01 Dec 2019 10:43 AM PST

Why aren't the bows of submarines pointy??

Posted: 01 Dec 2019 03:14 PM PST

Wouldn't a pointed bow cut through the water better?

submitted by /u/unbeatable_101
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Could there possibly be black holes that formed from collapsing dark matter?

Posted: 01 Dec 2019 07:07 PM PST

If the universe is infused with dark matter, would it not have become "clumpy" due to gravity, just like normal matter did (forming superclusters, galaxies, stars, etc)? And therefore, would there not be black holes that formed as clumps of dark matter collapsed, with very little matter nearby?

submitted by /u/SurprisedPotato
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Does the brain send signals consistently to keep a muscle in the same state?

Posted: 01 Dec 2019 10:59 AM PST

When I, for example, hold one arm straight to the side, does the brain continuously give the signal to keep the muscle extended or does it just make the arm extend once and it will stay extended until a different signal comes in?

submitted by /u/Cathrandir
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If The Strait of Gibraltar was dammed up, how long would it be until the Mediterranean dried up?

Posted: 02 Dec 2019 06:20 AM PST

Is remembering a dream the same mechanism as remembering something in real life?

Posted: 01 Dec 2019 11:13 AM PST

For example, why is my memory so bad when it comes to dreams but not as bad with real life experiences?

submitted by /u/cristianthechinch
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Do some animals get rabies more often?

Posted: 01 Dec 2019 02:03 PM PST

I have read of both raccoons and bats getting rabies a lot. Is there something that makes them more likely to contract rabies? And if so why?

submitted by /u/evahgo
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How do axes of orbit for planetary bodies and their natural satellites work?

Posted: 02 Dec 2019 05:05 AM PST

​

For the Earth and the Moon, the ratio of mass between the Moon and the Earth is so weighted on Earth's side that the moon goes in orbit around the centre of mass of the Earth. However, suppose that we have two bodies that are similar in mass and size. Is it possible for a configuration to exist where there is an imaginary centre of orbit that lies on a straight line between the two planets' centre of gravity that they both orbit around, on opposite sides?

How would orbits of planets and large satellites work? Is there a reason for our solar system only containing natural satellites that are much lighter than their orbital planet?

submitted by /u/nesnotna
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Is temperature affected relativistically?

Posted: 01 Dec 2019 03:26 PM PST

So I'm no expert, but I've got an interested amateurs understanding of relativity. But it occurred to me I've no idea how these concepts related to temperature. Temperature is some measure of the speed of particles in a substance, so it seems it must be affected by relativity but how does it work out? Does this mean there's an absolute maximum temperature governed by C, and are there other relativity effects in play too? Or is temperature something defined in a way that makes these questions irrelevant?

submitted by /u/that_nerd_guy
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Can anyone explain to me, in layman's terms, what is meant by DeSitter, Minkowski, and anti-DeSitter space?

Posted: 02 Dec 2019 01:22 AM PST

I like to watch physics videos and listen to physics audiobooks that aren't necessarily made for physicists, but explain things like CPT symmetry, Bell's inequality, etc. in a way that most people would understand.

Usually I can at least understand the concept without fully understanding the actual equations behind it. But when I try to look up anything about DeSitter, Minkowski, and anti-DeSitter space, all the results are written in equations, and I haven't been able to find a simple explanation of these concepts.

Without dumbing it down too much, can someone help me understand what these terms actually mean?

submitted by /u/cscott024
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Why don't we define units of length and time in terms of Planck length and Planck time?

Posted: 01 Dec 2019 07:13 AM PST

Just historical reasons?

Technically this is closer to linguistics than physics but it relates more to the practise of physics than to the practise of linguistics so I have it flaired as physics.

submitted by /u/Hyolobrika
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Why does mustard almost always list its calories as 0 on food labels? Surely it has some calories, yes? If so, what's the real number?

Posted: 01 Dec 2019 03:18 PM PST

How do donated organs remain viable without blood flow?

Posted: 01 Dec 2019 09:45 AM PST

If someone sustains a heart attack, the muscle is damaged b/c of no oxygenated blood flow. When a heart is removed for donation, there's also no blood flow. Icing helps how? What is the window of viability? If the organ is implanted at the far end of the window, is there some substantial damage that might heal?

submitted by /u/NuclearExchange
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Is there a classification system for biological viruses?

Posted: 01 Dec 2019 02:00 PM PST

I'm making a social media loosely themed around viruses and how they spread from person to person, but I'm kind of stuck. I want to include a system for classifying posts, but I can't think of a name for it. I want the name to be simple and easy to remember, such as subreddits, categories, or areas. "Classifications" would be too complicated, for example.

​ I should probably mention that they won't behave anything like subreddits. That's just an example

​

Thing is, I really want the name of them to be themed around viruses in some way. So is there a simple word used to classify viruses?

submitted by /u/homelesspancake
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Would be the dying sun ejected material massive enough to allow the formation of a smaller star, a.k.a red dwarf?

Posted: 01 Dec 2019 11:19 AM PST

*Ejecting

submitted by /u/ska4fun
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Where do dubstep "wub-wub" sounds come from?

Posted: 01 Dec 2019 04:48 PM PST

Could someone with audio engineering background give me a quick rundown on where do these sounds come from? Are they processed samples? Completely synthetic? Is there some magic behind them? Is there a reason why they suddenly emerged a few years back and haven't really been used prior?

I am putting "Computing" as a flair, since I assume it's all digital processing. Physics felt too broad of a category for something dealing purely with sound.

submitted by /u/QubaHQ
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Does earth’s gravity affect the electromagnetic waves or any other kind of waves (not sea related)?

Posted: 01 Dec 2019 04:38 PM PST

How is the age requirements do dosage for kid drugs determined?

Posted: 01 Dec 2019 04:05 PM PST

Little back story. I have a year and 8 month old boy, he's big for his size, not fat just big. Some Medicines have a 2 years and older requirement and I was wondering how that age was determined? There's no way they just turn 2, some magic happens and medicines are ok for them now.

Stupid iPhone: The title should say "How is the age requirement and dosage for kids drugs determined?"

submitted by /u/thegreatvirginchad
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Why do some planets adopt elliptical, rather than circular, orbits?

Posted: 01 Dec 2019 02:25 PM PST

Can two unstable particles be in an entangled state that causes their decay to be synchronized?

Posted: 01 Dec 2019 09:44 AM PST

My intuition is that this would require hidden variables to work, since the wave function does not contain enough information to predict when a particle will decay. Beause the decay time is not a property of the wave function there would be no part of the particle's wave function that could be entangled to ensure that they decay at the same time. But I could easily have overlooked something, so I'm asking to be sure.

submitted by /u/amaurea
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Why exactly does the smoke ring on smoked meats turn red?

Posted: 01 Dec 2019 02:28 AM PST

On smoked meats, the outer ring turns red when it's been smoked. And I was wondering why? The wood isn't red. The other parts of the meat doesn't turn red.

submitted by /u/Conn3ct3d
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Sunday, December 1, 2019

Do you weigh less at the equator because of centrifugal force?

Do you weigh less at the equator because of centrifugal force?

Do you weigh less at the equator because of centrifugal force?

Posted: 01 Dec 2019 02:14 AM PST

I am always confused be centrifugal and centripetal force. I am just going to state my thinking and help me point out the problem. At the equator your body is traveling fast in a circle and the inertia of your body makes you continue to move out-word, this is the centrifugal force. At the poles you are moving not at all or much slower in a circle so your inertia has less effect. With less out-word force the normal force, or your wieght, would have to compensate so you would weigh more. At the equator the centrifugal force lessons your weight ( not mass ) because it helps counteract gravity.

submitted by /u/HAMS-Sandwich
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Do animals sleepwalk like humans do?

Posted: 30 Nov 2019 12:57 PM PST

Does this have a documented answer?

submitted by /u/lAPPYc
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Do (long lasting) lava pools make any scientific sense? Or sense, for that matter?

Posted: 30 Nov 2019 01:09 PM PST

I have briefly recalled the game I played long ago, TES IV: Oblivion in which you get to enter demonic plains of said Oblivion. Those are always islands, surrounded by lava lakes, seas, also some smaller pools of lava on the exact islands.

Lava in the game is basically water, only it is scripted to damage you and obviously has a different texture. Otherwise you are free to swim in it as long as you can regenerate your hp fast enough. There are also plenty of other games where you experience exposed, long lasting lava pools.

Would that be possible on Earth? Wouldn't it just 'shell up' over time (upper layers got colder and toughen up)?

submitted by /u/ozbljud
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Does the consumption of high concentrations capsaicin interfere with our gastrointestinal microbiome?

Posted: 30 Nov 2019 10:25 AM PST

In clinical settings capsaicin has been used as both an antibacterial and antiviral. What are the effects on our microbiota?

submitted by /u/TheRevSev
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How come Nuclear Pasta is the strongest material on the universe?

Posted: 30 Nov 2019 04:42 AM PST

Can you pass/catch the flu virus to/from animals?

Posted: 30 Nov 2019 09:36 AM PST

Just a month or so ago, my mom and my grandma both got the flu (I'm guessing?) It may have been a severe cold but it lasted for maybe a week to a week and a half. After they get better my cat catches, what seems like, the same thing. He has snot running down his nose, he's drooling bc he can't breathe through his nose, he's lethargic, and he even had a little cough here and there. Fast-forward a few days after he's better and now I have flu like symptoms? But my symptoms have lasted almost 2 weeks now, they're better but not over. Maybe I sound dumb but I didnt think animals could catch most of human viruses? At least I've never seen it happen before. Thanks in advance for any answers anyone may have!

submitted by /u/Ditto_Ditto_Ditto
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How is this ice formation created on the ground?

Posted: 30 Nov 2019 12:41 PM PST

i.imgur.com/rLN8Fpr.jpg

Seems to occur on crust of mud, often where there's moss.

submitted by /u/emmazunz84
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Do environmental factors change the randomness in having a male/female in sexual reproduction?

Posted: 30 Nov 2019 07:41 AM PST

Question may sound a bit convoluted. i learned that the chances of giving birth to a male or female in sexual reproduction is always exactly 50/50. there is absolutely no way to control those chances in nature. that sounds hard to believe that something so important in nature is so random...

say you have a population of an animal. there are very few females, so reproduction rates are low, and competition among the many more males is extremely fierce and high. maybe this goes on for generations, could anything happen to the chances of having a male/female? maybe somehow, the chances of having a female increase so the population can grow in numbers faster and to alleviate competition. so maybe now the chances of males to females is a 35/65% chance... CAN this happen, DOES it happen? if so, how?

submitted by /u/NowItsKevin
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What is the flux gathering factor?

Posted: 30 Nov 2019 09:05 AM PST

Not sure if this is the right place to post this, but what is the flux gathering factor of a material or in a medium?

A google search only shows magnetic flux linkage - is that the same thing?

How would you calculate it in a medium subject to a uniform field?

Any help is appreciated.

submitted by /u/Raexyl
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Was The Far side of the Moon ever visible from Earth?

Posted: 29 Nov 2019 11:53 PM PST

How would a graviton enact an interaction with a photon near a black hole?

Posted: 30 Nov 2019 02:43 AM PST

So I was in class a couple of days ago and learned how the speed of information and causality is at c, (~300,000,000m/s). But I had a question regarding how photons would be pulled into a black holes event horizon if the speculated gravitons max speed is c. Say we have a relatively small black hole, and a photon is travelling near it, surely a graviton to enact an interaction between the photon and "attract" it to the black hole would have to catch up to the photon which would mean it travelling faster than c. And also, the information that there is a photon near the black hole would require time to be "processed", in which time surely the photon would already be outside of the black holes gravitational field, far before a graviton can be made aware of the photon to enact an interaction?

Thanks for responses in advance!

submitted by /u/JackTalle
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How do intestinal microflora adapt to dietary changes?

Posted: 29 Nov 2019 11:48 AM PST

When a person changes their diet, like when trying to lose weight by shifting away from processed foods to more whole foods, how does that affect the populations of different bacteria in their digestive tract? How long does it take for the populations to adapt?

submitted by /u/soylentbleu
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