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Monday, May 23, 2016

Are things like peanut butter, cream cheese, jellies etc. considered a liquid or a solid?

Are things like peanut butter, cream cheese, jellies etc. considered a liquid or a solid?


Are things like peanut butter, cream cheese, jellies etc. considered a liquid or a solid?

Posted: 22 May 2016 04:35 PM PDT

Do planetary orbits cause measurable "tides" on the surface of the sun?

Posted: 22 May 2016 02:39 PM PDT

Does this affect sunspots and solar storms when the planets line up?

submitted by /u/TheBlueCoyote
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When one stands on the moon, would the horizon appear to be closer, since the moon is so much smaller than earth?

Posted: 22 May 2016 11:40 PM PDT

Have we ever converted energy to mass?

Posted: 22 May 2016 11:17 PM PDT

If a disc was spun at 1 RPM, how large would this disc need to be in order for the edge of it to reach the speed of light?

Posted: 22 May 2016 09:53 PM PDT

Such a weird question, but I've been thinking about this for much longer than I'd like to admit.

submitted by /u/--lolwutroflwaffle--
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How can you have ohmic resistors if resistance causes heat increase and heat increase causes higher resistance?

Posted: 22 May 2016 12:44 PM PDT

So filament lamps are non-ohmic because if you increase the voltage across them then the charge carriers disipate more energy in the resistance of the lamp, causing it to heat up, increasing the resistance, and therefore reducing the increase in current with each increase in voltage. Therefore they are not proportional and therefore it is non-ohmic.

With an ohmic resistor, surely as current passes through the resistor, the resistor heats up and increases in resistance just like with the filament lamp and therefore not ohmic because the resistance is changing?

Or am I missing something?

submitted by /u/Spacecow60
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Could a fiber-optic cable be modified to work as a periscope?

Posted: 22 May 2016 10:52 PM PDT

We were learning about fiber optics in school and my mind started wandering and it got me wondering…normally in a fiber optic cable the light from the incoming image ends up horribly distorted before it comes out the other end because of the amount of times it reflects of the inside "walls" of the cable, but if you could have a cable made of say a million or so cables within a cable, each cable could carry a unique signal or point of light like a pixel on a tv screen. So, if you could take an image and focus it into a small area using a lens (or series of lenses), an area probably close to the point where all the rays of light converge, you could then transfer the image through the cable and then do the reverse process on the other side where the image could be projected on to a screen.

I don't see why this wouldn't work, besides the construction challenges. To create a 1MP image would require a million individual (optically insulated) cables which would have to be very small. If they were, say 9μm in diameter, you could fit 1,000,000 of them in a 3mm2 area

Maybe it has already been done, and i think there could be many applications for this if it was economical to produce, not to mention the novelty factor, but i get the feeling that the cost to produce something like this would not be worthwhile in a world where everything is digital.

submitted by /u/TheRealFalconFlurry
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The Earth is an oblate spheroid, but what about the atmosphere? Does it fit the shape of the Earth or is it more perfectly spherical?

Posted: 22 May 2016 08:23 AM PDT

I was reading about how Everest is the highest point above sea level, but Mount Chimborazo is the farthest point on Earth from the center. Does the atmosphere fit these bulges in the Earth's shape? Or does it fit as a sphere around Earth? If the atmosphere is perfectly spherical, the air at the top of Chimborazo would be thinner than at the top of Everest, right?

submitted by /u/agoyalwm
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Do gravitational waves/gravitons have angular momentum?

Posted: 22 May 2016 08:46 PM PDT

Why can there not be an n=0 mode on a waveguide?

Posted: 22 May 2016 01:04 PM PDT

Take an elastic membrane for example.

http://people.seas.harvard.edu/~jones/ap216/lectures/ls_1/ls1_u8/ls1_unit_8104.gif

My physics notes say there has to be at least one oscillation in the x direction: why can it not be flat in the x direction, and a wave travelling down the z direction like normal?

submitted by /u/eebootwo
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What is the origin of the stellar types classification letters?

Posted: 23 May 2016 12:44 AM PDT

Hi everybody!

Does anybody know why the spectral types are called like that, i.e. O, B, A, F etc?

submitted by /u/ivanmarvin
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How did scientist succeed to create an acoustic black hole ?

Posted: 22 May 2016 08:34 PM PDT

Is it possible to know what color a material will be without actually seeing it?

Posted: 22 May 2016 11:58 AM PDT

If so, what details would you need to know?

submitted by /u/BLACKAP3RTURE
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How does the body cope with the presence of heavy metals in the circulation?

Posted: 22 May 2016 07:42 AM PDT

When I did my Osteopathy undergraduate degree many years ago, I recall learning that molecules with a molecular mass greater than six kilo-Daltons could not pass through the basement membrane of the kidney, which meant that heavy metals such as mercury and lead (and other nasties such as DDT) could not be excreted, and were consequently stored in the liver until death. Yet, in the 19th century, hatters were driven mad by mercury. (Hence, the behaviour of the Mad Hatter in 'Alice in Wonderland.'). For this to happen, I assume at least some of the mercury must have not been stored but have been free-floating in the circulation and made its way to the brain. Can anyone throw some light on this?

submitted by /u/Vincent_Black_Shadow
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Why are frozen-then-thawed bananas so sweet?

Posted: 22 May 2016 07:41 AM PDT

We peel and freeze bananas for smoothies. I accidentally let one thaw. It's predictably mushy, but also unbelievably sweet. Where does all that sugar come from?

submitted by /u/daveberzack
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Sunday, May 22, 2016

What is the earliest song in human history that we are not only aware of, but have some idea of how it sounded?

What is the earliest song in human history that we are not only aware of, but have some idea of how it sounded?


What is the earliest song in human history that we are not only aware of, but have some idea of how it sounded?

Posted: 21 May 2016 11:14 PM PDT

I don't mean the earliest that modern society is simply aware of once existing through references or mentioning in early history, but the earliest song that we could at-least make an honest educated attempt of recreating the sound of. This could mean ancient sheet music of some form, or other means of accurately guessing how it sounded in person.

A separate question on a similar note; Do we have any idea when humans (or our non-human ancestors) first started making music recreationally?

submitted by /u/AcclimateToMind
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What is the square cube law?

Posted: 21 May 2016 06:45 PM PDT

I'm sure it's been said but explain it to me like I've never heard a word of anything remotely scientific and I'm brain dead.

submitted by /u/Johnnyze
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Is there a speed a cell phone can go to not receive wifi or cell signal anymore?

Posted: 21 May 2016 04:49 PM PDT

If I am moving at near the speed of will I still get lte?

submitted by /u/MutatedGamer
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What exactly does a blast cap do?

Posted: 21 May 2016 11:14 PM PDT

From what I hear large explosions can be pretty difficult to detonate (such as C4). I hear physical force, raising temperature and a flame doesn't set it off (although I may have heard wrong). What does a blasting cap do to make something detonate?

submitted by /u/CanYouDigItHombre
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Is there a pattern in the mersenne primes?

Posted: 21 May 2016 07:42 AM PDT

I saw a numberphile video on Mersenne primes, and I found out that sometimes 2 to the N - 1 is sometimes a prime. So I was wondering if there is a relationship between the Exponents, N, in Mersennes. Please explain in simple terms.

submitted by /u/mindfrom1215
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What would happen if a single atom of, let's say carbon, hit you at (1/2)c?

Posted: 21 May 2016 11:51 AM PDT

This question was inspired by a question from a few weeks ago about a tic tac at (1/100)c. I want to know if it would vaporize you or just punch a very small hole out of you.

submitted by /u/Ehvasion
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If you were to open a can of soft drink inside a zero-gravity space station, what direction would the bubbles leave in?

Posted: 21 May 2016 10:09 AM PDT

A friend was asking me the other day and after thinking for a bit i wasn't too sure.

submitted by /u/Marshmallo_man
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Why do we give pressors in patients with shock?

Posted: 21 May 2016 11:53 AM PDT

If increasing systemic vascular resistance (SVR) increases the afterload, doesn't that reduce stroke volume?

submitted by /u/xanderq
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Why don't we go straight up or down to exit the solar system?

Posted: 22 May 2016 01:36 AM PDT

If our solar system is on a linear plane, with everything orbiting the sun on a relatively flat field, why don't we just go straight up or down to exit the solar system? Why can't we just "hop" an asteroid fields?

I don't post here often, but I figured this is the best place to get an answer.

submitted by /u/Snooshii
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How do T-cells know which cells they've already inspected?

Posted: 21 May 2016 10:21 PM PDT

From what I understand, T-cells are constantly traveling in the body, inspecting cells by looking for antigens. If they're self antigens, then the T-cell doesn't attack, whereas if they're non-self, they attack. My question is how does a T-cell know when it just inspected a cell? Does the T-cell leave something behind on the cell to mark it as checked or does the cell itself present something on its surface to indicate that it has just been checked? If there is no such system, then what prevents the T-cells from being stuck in a loop, and just inspecting the same cell over and over?

submitted by /u/EmpiricalMind
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If you were to make a hole all the way through to the mantle, what would happen?

Posted: 22 May 2016 05:57 AM PDT

Lets assume you have a magic heat-proof drill of a ludicrously powerful shaped charge or laser or something that will make a hole, say, a couple of meters wide straight down all the way through the crust where I am in the UK.

Would you get an instant volcano? Would the results be different if it were under the ocean, where the crust is thinner (or have I got that backwards?). I suspect the planet doesn't just deflate like a balloon...

submitted by /u/ReCursing
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Would the night sky have appeared much brighter in the time of the dinosaurs?

Posted: 21 May 2016 09:59 AM PDT

Given that the universe is expanding, and that apparent brightness of celestial bodies is governed by the inverse square law, would there have been a noticeable difference in the brightness of the night sky during, say, the early Jurassic Period?

submitted by /u/T_at
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Do we burn more calories when ill?

Posted: 22 May 2016 04:19 AM PDT

Ill is a vague term, so lets specifiy a few common types of Ill:

  • item 1 Head cold: Cough, Runny nose/sneezing.
  • item 2 Flu: Aches/Pains, Fever, Vomiting
  • item 3 Stomach Flu: Abdominal pains, Diarrhea, Vomiting

Some of these may cause short term weight loss, but thats probably through minimised calorie intake, and expulsion of liquid, but do we also use more calories to enhance the immune response and fight the infection? Or is the immune system under constant stress and it just tailors the response to a specific event?

submitted by /u/Scalextrix
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Does spacetime spin around a black hole? Not just the matter, but spacetime itself. If so, what IS spacetime and what does it mean for it to spin

Posted: 22 May 2016 05:32 AM PDT

Also, why does lots of gravity make a person falling into a blackhole seem to be frozen in time from the perspective of an outside observer.

submitted by /u/badbrownie
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Is it possible for Jupiter to get enough mass through asteroid impacts to ignite fusion? How much more mass would it need? Is there any evidence of binary systems forming this way?

Posted: 22 May 2016 12:55 AM PDT

Is the time between introduction of an antibiotic and emergence of resistance to said antibiotic longer for fully synthetic antibiotics vs. antibiotics based on natural product?

Posted: 21 May 2016 10:18 AM PDT

I was just wondering if emergence of antibiotic resistance can be correlated to the origin of the drug.

Eg, does resistance emerge quicker with the natural based Beta Lactams or Macolides vs. fully synthetic Fluoroquinlones or oxazolidinones.

My thoughts are resistance would already exist for natural products so emergence could spread rapidly, compared to fully synthetic molecules, because resistance genes/mutation exists within the gene pool already; but that is of course just my hand-waving nonsense conjecture.

submitted by /u/darkstar000
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Is light it's own element? What is a particle of light made of?

Posted: 22 May 2016 06:39 AM PDT

Why does light decay?

Posted: 22 May 2016 05:48 AM PDT

How common has muscular hypertrophy been, historically?

Posted: 21 May 2016 06:30 PM PDT

In modern times muscular hypertrophy is relatively common as athletes and enthusiasts have developed lifting and dietary regimens which support that physique.

How common was muscular hypertrophy in each era, decade, or century? What caused the popular rise in hypertrophy as a fitness goal? What caused the rise in plausibility of attaining a hypertrophic physique?

submitted by /u/ADudeLikeAnyOther
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Why does the stress-strain graph of a material round off as it breaks?

Posted: 22 May 2016 04:20 AM PDT

This diagram shows that after the Ultimate Tensile Stress is reached, the stress reduces and the extension increases until is breaks.

http://206.214.218.178/~stressindicators/smartbolts/wp-content/uploads/sites/4/2015/08/Fundamentals-of-Basic-Bolting-1024x543.png

Surely though, as something breaks its cross-sectional area reduces until it reaches zero, at which point it has disconnected. Therefore the stress (Force / Area) would increase?

And so the graph should tend towards infinity at the maximum extension?

submitted by /u/Spacecow60
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If mountains can only form on plate boundaries, why are there so many mountain ranges in North America?

Posted: 21 May 2016 10:21 AM PDT

According to this map, the boundaries of the North American plate stretch from the Pacific coast to the mid Atlantic, and everything I've read about mountain formation seems to indicate that mountain ranges can only form on plate boundaries, so how did the Rocky Mountains and the Appalachian Mountains form?

submitted by /u/Norcon72
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What happens when one whips cream?

Posted: 22 May 2016 03:27 AM PDT

Why does it change so drastically?

submitted by /u/TheMagicSumthing
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Why is there a hole in parachutes?

Posted: 22 May 2016 02:27 AM PDT

Surely the most amount of surface area on a parachute would be the best. Then why is it that most parachutes has a hole in the middle?

submitted by /u/RomanticApplePie
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Saturday, May 21, 2016

In a double slit experiment, is there a minimum necessary distance between the photon (or other particle) source and the slits in order to see interference?

In a double slit experiment, is there a minimum necessary distance between the photon (or other particle) source and the slits in order to see interference?


In a double slit experiment, is there a minimum necessary distance between the photon (or other particle) source and the slits in order to see interference?

Posted: 20 May 2016 07:57 AM PDT

If we put the laser/source right up against one of the slits, surely we wouldn't get two slit interference, no?

If there is a minimum distance here, does it depend on the type of particle? Also what happens if we reflect the photons off a mirror on their way to the slits? In this case, is the relevant distance the total distance or only the distance from the mirror to the slits?

Edit: after some googling, I think I'm asking about the wave packet dispersion relation, discussed here, especially Dominique's final equation.

I want to know a) if interference requires sufficient dispersion for the wave to cover both slits and b) if the wave hitting a mirror (pre-slits) is a measurement-style interaction that causes its Gaussian to become fairly narrow/well localized again, which might prevent the wave from covering both slits.

submitted by /u/Exlizard
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Would trees grow taller in reduced gravity?

Posted: 20 May 2016 02:59 PM PDT

I've seen forests where one tree can outgrow all those around it and stays on top. This suggests to me that the smaller trees have hit a maximum height that they don't grow past, despite a different species of tree that is able to grow taller under the same conditions. Is there physical or biological limits that halt a tree's growth once it reaches a certain height? And if you get rid of gravity, could that tree grow indefinitely tall?

submitted by /u/superhelical
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How scientifically legitimate is commercial DNA testing to identify ethnicity? 'biology'

Posted: 20 May 2016 03:16 PM PDT

There have been many different sites over the past few years claiming that they can do anything from determining if you are related to this or that famous person (which to me personally seems absurdly improbable) to determining your ancestry more broadly in terms of ethnicity and a general background.

I'd like to hear from a few geneticists, biologists or any related field on how credible sites like 23andme are and their accuracy when it comes to identifying your ancestors' background, their ethnicity and possibly even their nationality.

Thank you in advance.

submitted by /u/alezit
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Would shooting a grenade actually cause it to detonate?

Posted: 20 May 2016 03:07 PM PDT

Sorry in advance if this is the wrong sub, but it's something you always see in movies or video games, but how accurate is that? I know some explosives, like C4, will only detonate if the right detonator is used, is the same true for grenades?

submitted by /u/Something_Syck
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Was CMBR visible light in earlier periods of the universe?

Posted: 20 May 2016 03:37 PM PDT

If Cosmic microwave background radiation was once gamma but red-shifted to microwave, does this mean that at some point the photons we are receiving would have been within the visible spectrum of light in earlier period in the universe?

If so when?

submitted by /u/SamThePotato
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How does photooxidization work during the process of glass solarization?

Posted: 20 May 2016 08:51 PM PDT

Im trying to understand how ultraviolet light induced oxidization can cause electrons to...stop?

If gaps in the color centers are being filled with electrons, how is the color change based on the added electrons interaction with the light spectrum? Does the number of electrons in the gap influence the spectrum shift?

Is there any cheap way to test what acquired crystallographic defects have in the nonvisible light spectrum?

submitted by /u/Flatwoods
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Is it possible to halt a light beam with light?

Posted: 20 May 2016 09:36 PM PDT

I was reading about destructive interference, and I suspect that this might give some insight to my question, but I don't know if it totally answers it.

Basically if there are two lasers perpendicular to one another, could one beam act as a wall so that the other does not shine beyond it? If it is possible to do is it dependent on the actual wavelength of the light, or is it relative (as in a blue laser would block a red laser but not a green one)?

Thanks in advance!

submitted by /u/BearFluffy
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How do we know that massless particles really are massless, and don't just have masses far too small for us to detect?

Posted: 20 May 2016 12:56 PM PDT

Is there a limit to how big a plane can get and still be able to fly?

Posted: 20 May 2016 03:35 PM PDT

What are some interesting finite numerical sequences?

Posted: 20 May 2016 11:33 AM PDT

Most "general interest" mathematical sequences we hear about are infinite. What are some finite mathematical sequences which are of general interest?

submitted by /u/GeneReddit123
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Why do we use Vega as the 0.0 for Apparent Magnitude of stars?

Posted: 20 May 2016 01:24 PM PDT

Can a photon only interfere with itself?

Posted: 21 May 2016 04:23 AM PDT

In the double slit experiment, if we turn down the intensity of the light such that only one photon is emitted at a time, there is still an interference pattern indicating the photon interfered with itself to produce the interference pattern. Therefore, is it true that photons can only interfere with themselves?

The reason I ask is that relativity says simultaneity is in the eye of the observer. So, if we have photons A and B, one observer might "see" them enter the slits at the same time while another would say one preceded the other and couldn't have interfered.

Therefore, would the only way for interference to happen is with a single photon always interfering with itself?

submitted by /u/BinaryHelix
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Do different wavelengths of electromagnetic radiation have different stabilities?

Posted: 20 May 2016 12:12 PM PDT

We all know that matter can be unstable or stable, hence things like high reactivity and decay. Would different types of waves such as a high energy gamma ray be more prone to decomposition compared to say visible light?

submitted by /u/Treebeardthegreat
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Why does biting something help deal with pain?

Posted: 20 May 2016 01:58 PM PDT

Like the phrase "bite the bullet", you would be given something to bite down on during certain procedures. Why does biting down on something help?

submitted by /u/nickrenfo2
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Best material/stuff to look at with a 400x microscope?

Posted: 20 May 2016 10:25 AM PDT

I am a science teacher looking for cool stuff to look at with my school microscopes. Highest magnification is 400x

submitted by /u/opivyfever
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What would be the effect of removing mosquitoes from the ecosystem?

Posted: 20 May 2016 08:35 AM PDT

CDC said that there have been >100 instances of Zika in the U.S. so far, which reminded me that there is a company, Oxitec, which has been marketing genetically modified mosquitoes that would eliminate mosquito populations through breeding in areas prone to mosquito-borne illnesses.

Is anybody familiar with the outcomes/results of these efforts to date in the places where they have been tested? Have mosquito populations been eliminated? Have relevant infection rates decreased? Has there been other observable damage to the surrounding ecosystem?

More broadly, how important are mosquitoes to their ecosystems? Does it vary significantly from place to place such that this is an impossible-to-answer question, or are there things we can say generally about the expected effects of using Oxitec's mosquitoes (or some other form of broad mosquito elimination) on surrounding ecosystems?

submitted by /u/skybelt
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Can silicon make the same sort of variety of compounds as carbon?

Posted: 20 May 2016 04:31 PM PDT

Since carbon and silicon are both in the same group, can silicon make the same variety of compounds as carbon? If it can, what properties do those compounds have in comparison to organic compounds?

submitted by /u/Popopopper123
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What specific type of continuum is the concept of Space-Time?

Posted: 20 May 2016 07:16 AM PDT

I know I'm out of my depth, but what label would be correct? For example, is it a homogeneous decomposable continuum?

submitted by /u/You_Lack_Hatred
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Where do photons "appear" from when an electron loses energy?

Posted: 20 May 2016 11:36 AM PDT

I'm learning about this currently, and I wasn't able to get a good answer as to where the photon comes from? My understanding is when the electron loses energy, it jumps down am orbit and the energy is released as a photon. Is the photon released from within the electron?

My knowledge is more than likely a very simplified way of how it works, and I was hoping it could be expanded on. Thanks:)

submitted by /u/cola5000
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I know we can move through time faster, but is there any way we could move through time slower?

Posted: 20 May 2016 07:46 AM PDT

I was thinking about time travel. If I get in a space ship and swing around a black hole or move at the speed of light, and I return to my original position in space say a year later (for me), I traveled through time at a different rate than everyone else and everyone I know and love will be much older or long gone depending on how fast I traveled.

Is there any way to do the opposite?

Imagine if you will... scientists create some sort of huge self-sustaining bio-dome with it's own atmosphere and the technology and fuel to sustain it for say 100,000 years. Would there be any way to send it somewhere and in a year when it returns (if it returns), 100,000 years would have passed for life in the bio-dome, and we could see the results of 100,000 years of evolution?

Trying to think of a scenario of how this could happen. The universe is expanding. Are some parts of the universe expanding faster than other parts? Would it be possible to say use a worm hole (assuming we could create and control one) to place an object in another part of space that was going faster through time than we are? Then (again with the worm hole), get it a year later? Any other possibilities?

submitted by /u/ckohtz
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