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Monday, May 8, 2017

Is the phrase, a star that shines twice as bright but half as long a true statement?

Is the phrase, a star that shines twice as bright but half as long a true statement?

Is the phrase, a star that shines twice as bright but half as long a true statement?

Posted: 07 May 2017 11:14 PM PDT

What controls the brightness of a star?

submitted by /u/RoskoJ
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Do gas giants like Jupiter and Saturn have a "surface" somewhere down there?

Posted: 07 May 2017 01:40 PM PDT

The way I imagine it now is a moon sized super dense core surrounded by massive amounts of gas. I've always been confused about this.

submitted by /u/GordonSemen
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Why do matches stick to a magnet after being burnt, but not before?

Posted: 08 May 2017 07:16 AM PDT

Is two identical ball shape but with different weight will fall a the same speed in air ?

Posted: 08 May 2017 03:14 AM PDT

Is there agreement that birds evolved 135 Ma ago?

Posted: 08 May 2017 03:13 AM PDT

In this NYT article, they say:

The 10,000 species of flying birds have tinkered only slightly with the design perfected over 135 million years ago, when Mesozoic birds evolved the modern flight stroke.

I'm curious how they know so precisely when birds evolved. When I looked on Wikipedia I found two articles on bird fossils dated to the 135 Ma range. I'm quoting Wikipedia here but on we go. Wyleyia is known by a single worn humerus. Gallornis is known by a femur and a humerus. Is that enough to build consensus on the origin of birds? How is this grouping of birds defined? Are birds continously present in the fossil record form 135 Ma on?

Because I heard in a lecture a couple of years back that the origin wasn't that certain and that avians only really bloomed agree the KT mass extinction.

submitted by /u/WhyYouShouldCare
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If you fire a bullet out of a gun, and simultaneously drop a bullet to the ground, they will land at the same time?

Posted: 07 May 2017 04:49 PM PDT

I was listening to Joe Rogan taking to Neil DeGrasse Tyson. They were discussing snipers & the curvature of the Earth. Then Joe says "If you are holding a bullet in your hand & drop it, and fire a gun at the same time, they will both hit the ground simultaneously" (paraphrasing)

Is that true? That seems outrageous! How does that work?

submitted by /u/OberonClone
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Is there a Universal Allergen? Some substance which causes an allergic reaction in EVERYONE?

Posted: 07 May 2017 05:16 PM PDT

Graphene has an ultrahigh electron mobility, how does that effect the current capacity?

Posted: 08 May 2017 04:59 AM PDT

Considering how graphene's electron mobility could reach to (200,000 cm2 V −1 s−1) could that lead to higher current flow? Can graphene carry magnitudes of current more than copper at a significantly low weight(considering the 1atom thickness x area x Density)?

Considering how 1kA of current is carried by large(volume) and heavy bus bars, I can imagine graphene doing the same with a significantly lower weight.

submitted by /u/9tothe9
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In all of history, which species had the least total members?

Posted: 07 May 2017 03:44 PM PDT

I've been wondering lately which species, current or extinct, had the least total number of members throughout history. It's a pretty difficult thing to just try to search for online, because the only stuff that comes back is stuff about currently endangered animals. In fact, I made a reddit account (this one) just to ask someone this question.

If you think about all the weird, obscure endemic species that have existed, some of them must have not had very many members of their species. Things that evolved in tiny, closed-off ecosystems (ie, Movile Cave) wouldn't have had the same numbers as things that exist/ed widely. For example, some cave-dwelling centipede that only ever has been found in one single cave may have only ever historically had a few hundred thousand members ever to exist, whereas krill has probably had quadrillions over history.

So, does anyone know any specific species that fit this bill? Or is this a dumb/unanswerable question? What is, in effect, the rarest creature of all time?

submitted by /u/Mr_Brumbo
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If the core of the sun is 15,000,000 K, why is the surface temperature only 5,772 K?

Posted: 07 May 2017 11:38 PM PDT

What is it that keeps the surface of the sun much cooler than the core of the sun? Why do the convective and radiative zones of the sun not transfer this heat to the surface?

submitted by /u/Flandardly
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What do storm clouds do that make them darker compared to regular, lighter clouds?

Posted: 07 May 2017 11:38 AM PDT

If I soak paper in saturated salt water, will the paper conduct electricity?

Posted: 08 May 2017 03:14 AM PDT

Hi there, I'm using Makey Makeys for this project where people can "hear" art by touching it. Currently, I am using graphite pencil and creating pencil-art by coloring in, which connects to the makey makey. But it gets tiring to keep coloring with 5B pencils for so long.

Would soaking paper in salt water conduct electricity? (Paper will be dry later)

submitted by /u/TheGuyfromRiften
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Is the strong force stronger between proton and proton than proton and neutron? If not, is it easier to eject a proton from the nucleus than a neutron?

Posted: 07 May 2017 12:37 PM PDT

Can a beta radiation source change, so that it radiates for example gamma radiation?

Posted: 08 May 2017 02:00 AM PDT

How do we know that Earth has a liquid outer core, but solid inner core?

Posted: 07 May 2017 03:03 PM PDT

How does a computer processor generate heat?

Posted: 07 May 2017 04:30 PM PDT

Are songs on the outside of a vinyl more detailed than those closer to the rotation axis?

Posted: 07 May 2017 01:39 PM PDT

Since the rotational speed doesn't change, the linear speed on the outer part of a vinyl is greater, right? So more information is being within a given time. Y'know, the needle will meet more "bumps" in one second when it's far from the rotation axis than when it's closer. Does this mean the music is more detailed?

submitted by /u/Narcotle
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In a two-block system, the two blocks collide forming an inelastic collision. If kinetic energy is conserved how does the velocity of the center of mass remain the same?

Posted: 07 May 2017 12:07 PM PDT

Edit: Not conserved*

submitted by /u/Th3_l3uster_
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Would a box with walls made of superconductors have zero magnetic field inside of it?

Posted: 07 May 2017 01:23 PM PDT

If you constructed a small box made of superconductors which completely sealed the inside of the box, would the inside have zero magnetic field even when a magnet is brought near the outside?

submitted by /u/ohpl
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At an atomic level, what is happening when you wet a paper towel and it becomes weak and breaks easily?

Posted: 07 May 2017 09:17 AM PDT

What causes light to refract and why is it so predictable?

Posted: 07 May 2017 04:13 PM PDT

I've read that light as an electromagnetic wave interacts with electrons in the material making them oscillate. The oscillating electrons then emit EM radiation (with a phase delay) which the initial wave interferes with. However I'm not quite sure how this results in the predicable behavior described by Snell's law.

submitted by /u/AntePantePp
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Massive black hole event horizon vs small black hole event horizon. Why are they different?

Posted: 07 May 2017 10:55 AM PDT

Why can you theoretically cross the event horizon of a large black hole relatively unscathed, but cannot approach a small black hole's horizon without being destroyed beforehand? Shouldn't the forces felt be the same at the event horizon, hence that's why it's the horizon?

submitted by /u/BobHopeWould
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Why do areas like western Scotland and Norway have such fragmented coastlines?

Posted: 07 May 2017 09:22 AM PDT
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Sunday, May 7, 2017

Do rainbows also have sections in the infrared and/or ultraviolet spectrum?

Do rainbows also have sections in the infrared and/or ultraviolet spectrum?

Do rainbows also have sections in the infrared and/or ultraviolet spectrum?

Posted: 06 May 2017 10:58 AM PDT

If iron loses its magnetism at around 1400°F, how is the earths core magnetic?

Posted: 07 May 2017 05:42 AM PDT

After reading a comment in another thread about heavy metals in our solar system I saw a comment stating that our core made of mostly molten iron is why we survive solar radiation (due to its magnetism).

Im not sure why I never queationed this before, but as an amateur blacksmith, I regularly heat iron up to a non magnetic temperature in order to quench and harden it.

Also I know there is supposed to be nickel in the outer core which is also a non magnetic metal.

So I did some research and found that it was believed to be cause by the dynamo effect caused by the swirling plasma within the core, but from my experience with plasma most of which comes from my home made arc furnace and of course the occasional plasma cutter (neither of which I have ever noticed creating any type of magnetic field), I dont quite understand how it alone, even if it were swirling, could create such a large magnetic field since the magnetic field of the earth is several hundreds of miles from the core. I also wondered how such a field were able to penetrate the miles of ferrous materiels found above it so easily while not magnetizing them.

Then I started thinking about other things that cause magnetism like electro magnets and such and wondered if maybe our cold iron cored moon plays a role in our magnetism by reacting with surface metals which are cool enough to be more receptive to magnetism.

So I researched that and found that the moon has little to no magnetism and unlike earth, its magnetism is non polar so there is no way the moon is the culprit of our magnetism because if it were then it seems it would also have to have magnetic properties similar to ours, and it doesn't.

Which brings me back to my original question only revised, how is our inner core of Iron plasma magnetic, and why is important that it is Iron plasma as opposed some other form of plasma if the swirling truly does create the magnetic field somehow?

submitted by /u/callmecraycray
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What actually is happening when programs load?

Posted: 06 May 2017 05:19 PM PDT

When a program loads, what changes to allow the user to use it? Also, how can some programs detect and display how loaded they are, when it isn't fully loaded?

submitted by /u/TheGigaGamer
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Can you do 100 edits on a single (human) genome with CRISPR, or is the number limited ?

Posted: 06 May 2017 06:06 PM PDT

I'm interested in both theoritical limitations and practical ones. I can't seem to find something about it in the litterature.

This is a question that is in a context of eugenics : would it be possible for parents to edit as many genes as they want, or would too many just be impossible (too long, too much errors, ...) ?

submitted by /u/Prae_
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What is the oldest known species of bacteria?

Posted: 07 May 2017 06:28 AM PDT

For clarification - not classifications, the single oldest known life

submitted by /u/Ryutauro
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How much energy is needed to create fusion and how much is produced by it?

Posted: 06 May 2017 06:56 PM PDT

Don't need a specific answer and thanks in advance!

submitted by /u/DaArabianGamer
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Is there anything you can add to water that would raise it's freezing temperature?

Posted: 06 May 2017 10:49 AM PDT

There's lots of stuff to lower the freezing temperature, from salt to antifreeze, but is there anything that raises it?

submitted by /u/acEightyThrees
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How do scientists do accurate spectropolarimatery on distant stars if some wavelengths are largely absorbed by the atmosphere?

Posted: 07 May 2017 01:40 AM PDT

How can peat burn underground? upto two meters apparently; where does the oxygen come from in these conditions?

Posted: 06 May 2017 10:27 AM PDT

Is it true that in exothermic reactions mass in doesn't r e a l l y equal mass out?

Posted: 06 May 2017 07:32 PM PDT

I came across an idea in a documentary I watched a long time ago that when paper is burned, a very very very very small part of its mass is converted to energy.

submitted by /u/huhwhatimsorry
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Why is it that the photon, an uncharged particle, is the exchange particle for the electromagnetic force?

Posted: 06 May 2017 06:04 PM PDT

I know I'm just a lousy,uneducated undergrad but I feel like there is a specific reason for this.

submitted by /u/Hunter_P_K
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Why are most pain relievers also fever reducers?

Posted: 06 May 2017 01:03 PM PDT

Would a water pump work better with rigid lines, or soft lines?

Posted: 06 May 2017 10:52 AM PDT

Putting in a water pump for my camper. Would a water pump work better with PVC supply and return lines? Or, something softer? Like a garden hose, or just something spongy like clear tubing?

submitted by /u/SailingPatrickSwayze
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Why do most if not all modern languages read either left to right or right to left? Why do none read top to bottom or bottom to top?

Posted: 06 May 2017 03:16 PM PDT

Is it possible to see past an event horizon? If not, why?

Posted: 06 May 2017 03:23 PM PDT

How does beta decay work?

Posted: 06 May 2017 11:38 AM PDT

So at School I learned that when a radioactive element does beta decay one it's neutrons splits into a proton and an electron. So far so good right, unfortunately I got way too much spare time so I wondered. If a neutron is made out of three quarks just as a proton, then where does electron come from? That are three fundamental particles that turn into four. Nothing can be added or taken from the Universe so the electron must have been around somewhere right? I even asked my teacher but she couldn't explain it either. Thanks for your answers.

submitted by /u/Kuunib
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Help understanding a few things about the electron?

Posted: 06 May 2017 06:39 AM PDT

Ok so first off, in school the electron is treated as if it has a specific radius. Obviously this isn't a proper representation of an electron because you can't properly define it. I was looking into electromagnetic dipoles and found that the magnetic dipole moment of an electron can be explained to be the consequence of its "spin", which is analogous to the spinning of a sphere in classical mechanics but isn't the same. I read that you can't treat it classically because an electron is really zero-dimensional and is a point-like particle and so doesn't have an axis on which to spin. So my question is basically which is it? Does an electron have a "size" or is it point-like?

Also as a side note, could someone tell me if the way I visualise an electron probability cloud is in any way accurate? So let's say you can be 70% sure that the electron is within a certain radius and 30% certain that it's within a larger radius. Can you treat it as though it's properties are spread out so that 70% of its properties (e.g mass, charge) are within the smaller radius and 30% effect the larger radius? Kind of like the electron is a cloud of gas which is more concentrated in the centre and therefore has more interactions there than further out.

I hope I've described myself properly. If I haven't please just ask for clarification. Anyway, thanks a lot in advance for any replies! :)

submitted by /u/Fellainis_Elbows
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Why does water, once being left for a long time (say overnight ), have lots of tiny bubbles in?

Posted: 06 May 2017 11:23 AM PDT

Through what process is the nucleus of an atom split when an atom bomb goes off?

Posted: 06 May 2017 05:07 PM PDT

Can you create a sonic boom underwater?

Posted: 06 May 2017 02:49 AM PDT

For fluids, higher velocity means lower pressure, but what happens when you change your reference frame to be the faster moving particles?

Posted: 06 May 2017 02:05 PM PDT

My Fluids professor showed a video of a ping pong ball sort of being "sucked" into a faster moving stream of air due to the lower pressure field resulting from the higher velocity. But what if your reference frame is one of the faster moving particles? My thought process is that relative to this particle, the air outside of the stream will be moving faster, so the lower pressure will actually be outside of the air stream. So then wouldn't that mean a tiny ping pong ball inside the air stream would actually get "sucked" or pushed out of the stream instead of into it like we have seen it do?

submitted by /u/AtheistPanda21
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Does water still expand if it is frozen in a vacuum?

Posted: 06 May 2017 09:02 AM PDT

How is the grain inside those "Magic Bag" pads affected by repeated exposure to microwaves?

Posted: 06 May 2017 07:15 PM PDT

I'm referring to these dingusses, which are essentially glorified water bottles. They are actually filled with grain, such as oats.

But what happens to the grains after repeated passages in the microwave, say about 100 times? They don't seem to burn ... why is that? And is that cumulative microwave exposure changing the materials inside in any way?

submitted by /u/Gargatua13013
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Saturday, May 6, 2017

Can you explain the logical leap from gravity to holographic principle?

Can you explain the logical leap from gravity to holographic principle?

Can you explain the logical leap from gravity to holographic principle?

Posted: 06 May 2017 02:04 AM PDT

I am already aware of the math behind (classical) thermodynamics, special relativity and quantum mechanics. How does gravity change the picture?

submitted by /u/thetimujin
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Do Reptiles have Jet Lag?

Posted: 05 May 2017 02:27 PM PDT

Hello there,

Right now I'm sitting on my studies and a question popped up that neither me nor any of my colleagues was able to solve. The thing is this: I read about the pineal gland(releases melatonin which is important for the sleep cycle/circadian rythm etc.) which is directly activated via the absence of light in lower vertebrates, while higher vertebrates possess the suprachiasmatic nucleus, that is concerned with innervating the pineal gland. Is this only because of the different organization of e.g. humans/reptiles, or is there a functional difference and if so, does this affect jet leg? I found an article (http://animals.howstuffworks.com/pets/pets-suffer-jet-lag.htm) where it is stated that dogs and cats suffer less jet lag than monkeys for example, but this does not quite answer my question. Why I specially ask about reptiles is that some of them possess the so called 'third eye' and the fact that they are somewhat dependend on the sun.

I hope I was able clearly state my question. If not feel free to ask, I'll do my best to clarify what I mean.

submitted by /u/5ong6
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Does the human body have 3 of anything?

Posted: 05 May 2017 02:15 PM PDT

Edit: A few of you have picked up on this.. yes I'm asking because we are mirrored left to right and have 2 of some organs.

submitted by /u/OllieSDdog
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How do we know it's 'quantum' uncertainty, and not uncertainty in measurements or interference from unknown factors?

Posted: 05 May 2017 12:09 PM PDT

Firstly, I don't mean to suggest that I don't believe the quantum interpretation. When I read articles about quantum mechanics, there is always a bit that says that a particle's position and velocity can't be measured to a certainty; there is always a random chance of finding either within a range, with probabilities determined by the wave function (as far as I can tell). For the sake of example, say we shot a particle at a given velocity, and then measure its position after a given period of time. If we determine the particle's velocity to be somewhere between 10 and 20 m/s, why interpret that as an indication of the particle's probabilistic nature, instead of assuming it's the effects of precision of the particle gun, the precision of the detector, the particle colliding with other particles on its way, etc?

submitted by /u/azamarahe
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How exactly does ATP allow a cell to do "work"?

Posted: 05 May 2017 11:00 AM PDT

How do electric vehicle batteries impact the environment? What are the elements used in creating them and how are they handled at the end of life cycle?

Posted: 05 May 2017 07:40 AM PDT

How is the area under sinc function (sine cardinal) and sinc square function finite but the area under absolute sinc function infinite when absolute sinc (x) is just the square-root of sinc square function?

Posted: 05 May 2017 11:57 PM PDT

∫ sinc (x) , (-∞,∞) = π

∫ (sinc x)2 , (-∞,∞) = π

∫ |sinc x| , (-∞,∞) = ∫ √(sinc x)2 , (-∞,∞) = ∞

I have seen mathematical proofs for it, but I don't understand how taking square-root of a function would make its area infinite from 3.14 units.

submitted by /u/lickmyspaghetti
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Why is particle production ~constant as a function of rapidity?

Posted: 05 May 2017 10:40 AM PDT

Hi all,

I'm currently brushing up on some HEP basics for an oral exam. One thing that I haven't been able to understand completely is why particles production is approximately constant as a function of rapidity in hadron collisions.

I've tracked down an old note of Feynman's which people usually point to about this: http://authors.library.caltech.edu/3871/1/FEYprl69.pdf ... I think that I understand what he's getting at when he discusses the Fourier transformation of the contracted field, but I don't see how to move from the ~constant particle Pz distribution to a multiplicity distribution that is ~constant as a function of y.

I know instinctively that this is true -- the ATLAS calorimeters are designed in a way that takes this into account, for instance. I'm just missing some conceptual link, and it'd be really awesome if someone could help me get all the way.

Thanks!

submitted by /u/WIZRND
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If the earth was a cube instead of a sphere, what would gravity be like at the edges?

Posted: 05 May 2017 08:47 AM PDT

What is the differences between a species group and a species complex in bacteria?

Posted: 05 May 2017 01:48 PM PDT

Examples of this are Enterobacter Cloacae complex and Streptococcus mitis group. What is the distinguishing difference between when you call a group of related species a complex or group?

submitted by /u/Jewronimoses
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Did the Earth have ice caps in the Mesozoic Era?

Posted: 05 May 2017 07:32 AM PDT

Portrayals of dinosaurs always seem to be in tropical/subtropical jungle. Was the entire earth like that or were there still areas with different climates?

submitted by /u/ErnstStavroBlowTree
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What is the difference between a magnetic monopole and charged elementary particle?

Posted: 05 May 2017 09:10 AM PDT

If an electron has no internal structure but it has an electric charge, what makes it not be a magnetic monopole?

submitted by /u/El_Skippito
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Why is there a huge difference in the nominal gdp of India and PPP gdp of India ?

Posted: 05 May 2017 04:28 AM PDT

Why do soils become less acid away from granite tors?

Posted: 05 May 2017 03:48 AM PDT

Hello. I'm writing an NVC habitat report and I've noticed that my Ellenberg factors indicate quite clearly a less acid pH as I progress from the upland tor to the lowlands. This is obviously due to the presence of shade loving, ubiquitous generalists in my species record as opposed to characteristic calcifugous moorland, but I'm not sure about the process itself. What is the factor or factors that cause a slightly less acid pH away from the granite tors? Is it simply a change in geology or is it the cause of the plants themselves? I was under the impression that plants accumulate hydrogen ions which make soils slightly more acid though.

submitted by /u/TaylorH93
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How is the FWHM of the quasi-elastic peak related to the diffusion of an atom in a solid in a quasi-elastic neutron experiment?

Posted: 05 May 2017 09:30 AM PDT
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