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Saturday, September 24, 2016

[Physics] when a star dies the explosion creates heavier element like gold and platinum. Is it possible to estimate the amount of a perticular element a star will make when it dies?

[Physics] when a star dies the explosion creates heavier element like gold and platinum. Is it possible to estimate the amount of a perticular element a star will make when it dies?

[Physics] when a star dies the explosion creates heavier element like gold and platinum. Is it possible to estimate the amount of a perticular element a star will make when it dies?

Posted: 24 Sep 2016 03:00 AM PDT

Is the exhaust from an ion thruster hot, reactive, or radioactive? Would it harm, say, a human hand?

Posted: 23 Sep 2016 11:27 PM PDT

I'm actually pretty shocked that I couldn't find any info on Google. From what I can tell, ion thrusters spit out propellant on the order of milligrams per second; low mass at very high speed. If you had your hand behind one, would this be more similar to a fan blowing dusty air at you or a shotgun loaded with sand-filled shells?

submitted by /u/king_aseg
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How does cutting smth work in a microscopic/atomic scale? Do we break the chemical bond btw the molecules (eg peeling a fruit)?

Posted: 24 Sep 2016 01:13 AM PDT

Do we break the chemical bond btw the molecules (eg peeling a fruit)? I know there might be different answers for different type of items, eg cutting a fruit/vegetable or cutting a meat, which is very different from cutting a wood. I think it would be different in chipping a iron ore?

submitted by /u/i_need_zzz
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How does hypoglycemia cause seizures?

Posted: 24 Sep 2016 06:19 AM PDT

navier stokes equation. 2 questions regarding it. basically, what is this proof about and why can it help?

Posted: 24 Sep 2016 04:47 AM PDT

going from this article

it states

The trouble is that no one has ever been able to prove that the equations don't sometimes 'blow up' and produce physically impossible results

and

Such a proof could lead to better aeroplane and boat designs, and improve weather prediction

so some questions.

  1. what does the first statement even mean? "prove" what about the equation?

  2. how come this proof will lead to what its stated by the second equation?

submitted by /u/Whatitsjk1
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Can brain damage alter what a person sees?

Posted: 24 Sep 2016 12:55 AM PDT

I know that our senses (eyes, ears, etc) just relay information to the brain, and the brain is what actually does the sensing (seeing, hearing, etc). So can damage to a specific part of the brain alter how the brain understands the data from our senses? Moreover, is it possible to change how the brain interprets the info from the eye for example, so as to create images that are not actually there?

submitted by /u/i_m_no_bot
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Why does facial skin is most likely to have pimple than elsewhere?

Posted: 23 Sep 2016 09:26 PM PDT

For example i don't have a pimple on skin of my forearm but got some on my forehead :)

submitted by /u/n_tvshn
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Why did we develop anxiety as an evolutionary advantage and why do so many people suffer from it today?

Posted: 23 Sep 2016 08:50 PM PDT

Evolution is survival of the fittest; so why/how is anxiety a "positive" thing that we developed and kept so strongly throughout our evolution?

This is not a call for religion vs science, so please don't go there in this thread.

submitted by /u/etiks
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In what order do bones develop when a baby is in the womb?

Posted: 24 Sep 2016 02:54 AM PDT

What was the chemical composition of the Earth's atmosphere prior to the Great Oxygenation Event?

Posted: 23 Sep 2016 09:08 PM PDT

I assume it was mainly nitrogen. Water vapor would be common since there's evidence of water almost immediatly after the Earth's formation, but since it was a hot planet, then I assume much of it would be in gaseous form. Carbon dioxide and sulfur were probably present in high concentrations due to the high volcanic activity. However, I'm just assuming all of this- I couldn't find any studies about it.

submitted by /u/JasontheFuzz
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What happens to the dipol-inducing wave energetically during Rayleigh scattering?

Posted: 24 Sep 2016 01:40 AM PDT

As far as I understand Rayleigh-Scattering happens when a EM wave hits a relatively small particle and induces a Dipol which emits a wave with the same wavelength. However, to induce that dipol some energy must be lost and therefore the color of the light would have to switch more towards the red spectrum? What am I missing?

submitted by /u/Doodlesulk
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Does the Leidenfrost Effect still apply to extreme temperatures that are too extreme?

Posted: 23 Sep 2016 11:28 PM PDT

For example: being near the point of lasers' focus at the National Ignition Facility in USA or near the temperature created by the Large Hardron Collider.
Just did a little reading and that stuff outputs insane amount of energy. LHC: 5.5 trillion K and NIF ~3 mil K

submitted by /u/Blobify
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What keeps sugar cubes together?

Posted: 23 Sep 2016 03:45 PM PDT

Or a better question: what's the difference between regular loose sugar and sugar cubes?

Something has to keep the sugar cubes... Well, cubes.

I know it has to be some kind of humidity, but is it water?

submitted by /u/sexy_tangerine
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What are the latest developments concerning prime numbers?

Posted: 23 Sep 2016 02:31 PM PDT

This topic seems to be researched by many - any new stuff?

submitted by /u/b4b
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If you were to reflect a photon between two perfect mirrors endlessly, would it eventually run out of energy from exertion of radiation pressure?

Posted: 23 Sep 2016 11:28 PM PDT

If you were to reflect a photon between two perfect mirrors endlessly, would it eventually run out of energy from exertion of radiation pressure? And what would happen to the photon once that occurred (since a perfect mirror can't absorb a photon)? Surely a photon can't just keep endlessly transferring momentum to the 2 mirrors?

submitted by /u/fagdgadfsgafg
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Does time gradually change and distort in a regular way between the quantum scale and the universe's scale?

Posted: 23 Sep 2016 08:37 PM PDT

Is that part of relativity as well?

submitted by /u/filmdc
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Where does charge come from?

Posted: 23 Sep 2016 10:58 PM PDT

I know that electrons have negative charge and protons have positive charge, and that opposites attract and the same charge repels, but where does charge come from? The spin of the particles? What makes positive charge different from negative charge?

submitted by /u/spmurgemag
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Does the amount of fusion change as a star evolves?

Posted: 23 Sep 2016 03:49 PM PDT

I'm researching the fusion processes in stars and am hitting some snags. I can't seem to find information on the amount of fusion that occurs in stars outside our own.

-How does fusion scale with radius and mass? I assume gravity is sucking in the hydrogen around it to give it a supply, so how can I scale that amount with the size and/or mass of a star?

-When a star starts fusing helium and creates layers of elements (like a Red Giant that has a hydrogen shell around a helium core), does the outer shell fuse more, equal, or less hydrogen than its previous form?

Basically, I'm kind of looking for some kind of equation for fusion based on the classification of a star. It doesn't have to be extremely specific, or perfect, per class. I just need some kind of starting point. I feel like I keep hitting dead ends with my hunches.

Thanks everyone! :)

submitted by /u/Darknuke
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Why do people think that everything is contained within π? Where did this idea come from and is there any logic or proof for it?

Posted: 23 Sep 2016 08:05 PM PDT

For the statement that everything is in π to be true, this would also mean that π is in π. A sort of π'ception would occur creating a repeating number making π a rational number. This raises additional questions: *Is π definitely a irrational number? *Is there any proof that it is? *How do we know that π doesn't? *How do they even calculate π?

submitted by /u/marnoch
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In theory, is gravity, as we know it, ubiquitous among the universes in the multi-verse theory?

Posted: 23 Sep 2016 06:28 PM PDT

Was thinking about the multi-verse theory - with infinitely differing timelines and matter, is gravity and the way it functions consistent among universes? Or can gravity function infinitely different ways in all these universes? Obviously this isn't known, but what is the prevailing theory?

submitted by /u/pengdrew
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Is an inertial dampener entirely science fiction? Or is there a theoretical way to actually make one?

Posted: 23 Sep 2016 08:02 PM PDT

When astronauts go into space, is there a certain area where they immediate feel Zero G, or do they gradually feel less and less gravity on their way up?

Posted: 23 Sep 2016 09:04 PM PDT
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Friday, September 23, 2016

If I put a flashlight in space, would it propel itself forward by "shooting out" light?

If I put a flashlight in space, would it propel itself forward by "shooting out" light?

If I put a flashlight in space, would it propel itself forward by "shooting out" light?

Posted: 23 Sep 2016 05:18 AM PDT

A woman with a long history with major chemical corporations told me yesterday that CO2, Diamonds and Pencil Lead were Organic, is she right?

Posted: 23 Sep 2016 06:12 AM PDT

Now to Clarify I work with this woman, L (chemist with history at major chemical producers)

I'm in the IT Department, we had dinner last night with another colleague (PhD environmental biology). Now during the meal they were chatting chemistry and L's work history and such, I wasn't paying full attention because I don't know anything about chemistry.

But basically it came up that anything that contains Carbon is organic. So, being curious I asked L if a diamond would be organic. She says yes, anything that contains carbon is organic. I ask if there's a difference between the term "organic" to a chemist as opposed to a biologist, she replies that "organic is just a Marketing term" but doesn't really answer my question and just acted a bit condescending about the fact that I don't have a chemistry background.

I asked a friend of mine who took high school chemistry and he said he'd never heard of it and that I should ask her if CO2 is organic, she says it is...

So my question, because she was rude and I wasn't interested in asking again, is

Is the term Organic meaning anything with carbon in it a term only used as such in chemistry?

I had learned that organic meant that it was an organism, that it had lived at some point or another.

TL;DR: My coworker told me that any carbon containing compound is organic, but I always learned that organic meant that it was once living.

submitted by /u/SevFTW
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Why does silver have a really high coefficient of friction with itself, but low when it has friction against other materials?

Posted: 22 Sep 2016 02:26 PM PDT

How can polarizations other than linear and circular exist?

Posted: 22 Sep 2016 07:31 PM PDT

I'm specifically curious about elliptical polarization. If my understanding of this is correct (and it may not be) photons must travel with their e and b fields perpendicular to eachother and to the direction of travel. This would make circular polarization equivalent to a rotating (along the axis of propagation) photon and linear polarization equivalent to a non-rotating photon. I was also under the impression the ratio of the e and b fields is a constant.

How are elliptical polarizations possible? Are one or more of the above incorrect?

submitted by /u/AlohaItsASnackbar
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What are the advantages of solid state waveguide lasers over diode lasers?

Posted: 23 Sep 2016 01:24 AM PDT

I've been hearing a lot of talk about waveguide lasers in the past years, but in what cases are they better than diode lasers? You need a diode laser to pump them anyway, right?

submitted by /u/medsl
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Could a beam of positrons directed at an atomic structure eventually cause the atoms to break apart due to electron/positron annihilation?

Posted: 22 Sep 2016 11:23 AM PDT

Can someone explain the octet rule?

Posted: 23 Sep 2016 01:16 AM PDT

I just attended a chemistry lecture about electrons and the periodic system (Basically just repitition). Long story short: My teacher either both denied and confirmed the octet rule in a span of about 10-15 minutes, or I have completely misunderstood the octet rule.

We were talking about potassium and its electron configuration and we determined that the configuration is 2,8,8,1. Then he asked if anyone could tell him why the N shell electron didnt stay in the M shell, since there technically is space for it. I said that valence shells cannot have more than 8 electrons (which, to my understanding, is the octet rule). He said that this was wrong. A while later we'd gone onto valence electrons, and since I was still convinced that there can be cannot be more than 8 valence electrons, I brought this up. At that point he said that valence shells can hold between 2-8 valence electrons, but no more, and denied saying otherwise.

I still don't understand what I've mistaken about this. Can someone clear this up?

submitted by /u/LegendaryZioke
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Do spherical harmonics, used to describe the electron distributions of atomic orbitals, find other uses in fields other than physics/ chemistry?

Posted: 23 Sep 2016 08:11 AM PDT

I feel like they would be used in areas of engineering (such as propagation of waves on a spherical surface?) but I couldn't find anything to go on. Maybe I'm wrongly interpreting what they actually are. The wikipedia pages don't shed any light on their history/ 'discovery'.

submitted by /u/Appaulingly
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What is the Quantum Field Theory?

Posted: 23 Sep 2016 08:05 AM PDT

Could the Chicxulub asteroid impact possibly have pollinated nearby planets/moons through panspermia?

Posted: 22 Sep 2016 08:56 PM PDT

In accelerators are elementary particles created from the energy of the collision or the proton somehow breaking apart?

Posted: 23 Sep 2016 02:57 AM PDT

(edit: When I mean "breaking apart" that the proton is "busted" into its constituent bits?)

submitted by /u/SubnetDelta
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Why do planets and moons tend to have orbits within a single plane, whereas some galaxies are relatively globular?

Posted: 22 Sep 2016 02:46 PM PDT

Is it possible to have a magnet where 100% of the domains point towards the same direction?

Posted: 22 Sep 2016 10:40 AM PDT

Like how you can reorganize which direction the atoms in a screwdriver face with a magnet. Is it possible to reorganize all of the atoms such that every atom faces towards the same direction? Can it occur naturally?

submitted by /u/coatstain
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How dangerous is it to handle Tritium?

Posted: 22 Sep 2016 01:08 PM PDT

If tritium was spilled on exposed skin, is it an immediate trip to the hospital? For context, I'm asking the question because I recently purchased jewelry with tritium vials inside of it and was curious of the potential risks if the vial ever broke on me.

submitted by /u/PM_YOUR_NICOLAS_CAGE
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Why is the Cape floristic region so small, what makes it a separate floristic region from the rest of South Africa, and why are there no similarly small regions elsewhere?

Posted: 22 Sep 2016 08:06 AM PDT

Genetics: Is The Only Way for a Man to Make a Detectable Genetic Contribution Through Successive Generations is to Have a Son, and A Woman to have a Daughter?

Posted: 22 Sep 2016 10:10 PM PDT

In studying genetics, it seems there are basically three standard variables of significance. The most obvious is mutations that endow an organism with enhanced reproductive success. The other two variables, on the other hand, are about continuity: that is, two fairly permeant aspects, that while they reflect past mutations, act as the twin pillars of conservation and inheritance, namely: the y chromosome and mitochondrial DNA.

Men and women are often said to have different reproductive strategies. But, underlying that, is there a broader question? That is, for a women to be able to have made a detectable genetic contribution to her descendants in say, 6 generations, does not that require that she have daughters, who have daughters, who have daughters. That is, her largest genetic imperative rests on the reproduction of women more than sons if she is to maintain her detectable genetic signature in successive generations.

Is this not also true for men, who to maintain a detectable link to their descendants, require that they have sons, who have sons, who have sons, etc.

Men are related to each other on the test by virtue of their haplogroup. Women are related to each other by virtue of their mitochondrial DNA. Over a succession of generations, is if fair to say that the only way to really link people genetically to an identifiable ancestor is through these two stable genetic markers. Or at least, the most stable.

All other parties, such as a man who has a daughter or a woman who has a son, certainly also contribute genetic information to their progeny. But might we not interpret that contribution as a more haphazard process, as part of a wider 'genetic lottery' of random assortment that serves to 'play roulette' and, by chance, come upon the next, mutated haplogroup or mitochondrial group that produces outsized reproductive advantages?

We see a child as being a basically a 50/50 reflection of both parents. But, beyond the basic reproductive differences between men and women (men can have a thousand children, women only a dozen), does the sex of a child have a direct impact on the ability of the male or female to maintain a detectable genetic signature--in a sense, to more clearly reproduce its unique genetic markers?

submitted by /u/frizzyhairdude
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What impact does our diet have on climate change?

Posted: 22 Sep 2016 08:56 AM PDT

How much does our diet effect climate change? I've read avoiding beef makes a difference, what about pork and poultry/eggs? Is the impact of dairy cows the same as those I get my tasty steaks from?

submitted by /u/biscuitsncheese
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Does a van de graaf generator make you positive or negative?

Posted: 22 Sep 2016 03:44 PM PDT

I'm really hoping for some sources here if possible.

I've been taught using van de graaf generator that the belt is taking away electrons from the dome and whatever is in contact with the dome. Which I thought would leave the dome positive and you positive, making Hair repel from each other.

Recently some stuff I read said it was adding electrons to the dome, making it negative charge.

I've done research and seem to be finding both answers the more I dig, even while searching site:edu

Can any one help me out with an answer and a solid source where I can see this explanation.

Thanks so much

submitted by /u/fightsfortheuser
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Why are melanocytes found in the heart and bones?

Posted: 22 Sep 2016 09:36 AM PDT

I know the function of melanocytes in the epidermis, but why are they found in deeper tissues?

submitted by /u/5cience_mama
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What is "silicone" cookware made of? Isn't silicone a silvery, crystalline metal?

Posted: 22 Sep 2016 09:01 PM PDT

How do vibrations without changes in dipole moment occur?

Posted: 22 Sep 2016 11:16 AM PDT

I'm confused. Here's what's confusing me:

If a molecule only changes its vibrational state when it absorbs energy. And it can only absorb energy from radiation when it leads to a change in the molecule's dipole moment, how the shit do vibrations that don't lead to changes in the dipole moment occur?

I actually have more questions on this but I'll start here.

submitted by /u/NewToUni
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Thursday, September 22, 2016

Is arsenical iron or arsenical iron pyrites hazardous?

Is arsenical iron or arsenical iron pyrites hazardous?

Is arsenical iron or arsenical iron pyrites hazardous?

Posted: 22 Sep 2016 05:46 AM PDT

I'm a science teacher and geology is not my strong suit. I just found a very old geology kit containing an immense amount of different types of rocks. However, one caught my eye: Arsenical iron. I looked around online and could not find this rock and if it was hazardous. I know arsenic is dangerous. Any help would be appreciated. Additionally just found primary and secondary uranium ore. Are these particularly dangerous? These are fairly big samples like size of a golf ball each.

submitted by /u/onwisconsin1
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Could an atomic bomb explosion be seen by someone standing on the moon?

Posted: 21 Sep 2016 04:17 PM PDT

What is the origin of human sexual fetishes? Why can some be so particular and even self-harming?

Posted: 21 Sep 2016 04:12 PM PDT

I can understand why humans would find things sexually attractive from an evolutionary standpoint, but some fetishes do seem out there and confusing. Some even self-harming. Like, cannibalism, BDSM, scat, castration, etc.

What led the human species to originally develop such fetishes?

submitted by /u/Josh_From_Accounting
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Does Diffusion Require Energy?

Posted: 21 Sep 2016 07:42 PM PDT

Does the process of diffusion affect the net energy of a system?

If so, is there a temperature at which diffusion will stop happening (above absolute zero)?

submitted by /u/tinkoh
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Does a neuron undergo multiple depolarizations within the same action potential?

Posted: 21 Sep 2016 05:46 PM PDT

I am challenging an exam question in a medical program for a physiology course.

During an action potential, the membrane "depolarizes", eg. crosses the threshold potential for a given neuron resulting in an action potential (becoming less "polar".

After hyperpolarization of the cell during the relative refractory period, the membrane would technically become less polar again as it approaches the resting membrane potential of the cell.

I realize this does not represent the conventional definition of depolarization when referring to an action potential, but based on technicality of definition of depolarization, isn't the membrane becoming less polar after the hyperpolarization of the membrane?

submitted by /u/Squidmaster2013
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Does the Radius of the Sun Oscillate Over Time?

Posted: 22 Sep 2016 04:49 AM PDT

As the title states, I viewed a video of the Sun earlier today and noticed what appeared to be major oscillations of its size over time, basically the Sun would appear to expand and then contract again.

I understand that this could be camera oscillations but I was wondering, would it be able to do that over even a small length of time like a day?

I understand star's will expand and contract over millions, perhaps billions of years based on activity and cool down and warm up respectively but on a time scale of days, doesn't seem right to me.

Help me /r/askscience, you're my only hope, Google isn't helping at all.

submitted by /u/WinOSXBuntu
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[Physics] Why do Materials sound the way they do?

Posted: 21 Sep 2016 02:22 PM PDT

How does the mass and molecular crystalline structure affect the way a material or an object sounds/vibrates?

submitted by /u/Relaxel
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What is the importance/usefulness of calculating earths capacitance?

Posted: 21 Sep 2016 02:37 PM PDT

In my physics lecture today we calculated the capacitance of the Earth as a nested spherical shell. I understand that the earth works as a capacitor as we ground things in the earth such as a home. The question I have is what else is the capacitance of the earth used for? Are there useful calculations involving it?

submitted by /u/coldjungles
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[ASTRONOMY] Did galaxies form at roughly the same time throughout the observable universe?

Posted: 21 Sep 2016 11:57 AM PDT

The farthest observed galaxy is 13.2 billion light years away. This puts it's formation at around 480 million years after the big bang. The Milky Way (to my understanding) is estimated to be 13.2 - 13.4 billion years old.

Does this mean that the energy that coelesced into the matter that formed the galaxies was spread throughout the universe in a relative instant? Was this due to expansion of space itself (faster than the speed of light?) How can galaxies be around the same age, yet be 13.2 billion light years away from eachother?

Sorry for so many questions, this has been on my mind for a while.

submitted by /u/SumthinCrazy
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Can we deduce any properties of an element from its emission spectrum?

Posted: 21 Sep 2016 05:07 PM PDT

Are people with nut allergies allergic to the rest of the plant?

Posted: 21 Sep 2016 01:30 PM PDT

Could for instance someone allergic to hazel nut react to a leaf from a hazel tree?

submitted by /u/Kogster
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If single-letter variable names are intolerable in programming, why are they the standard for formulas?

Posted: 21 Sep 2016 10:34 AM PDT

I have a BS & MS in CS, but I've been out of the academic world for some time. Recently while reading some lecture slides I was surprised to find how high the mental load of parsing long formulas written in the usual greek alphabet is when you aren't working with them daily anymore.

A fictional example,

If one would never consider it acceptable to write code with variable names such as:

int a = (r * (b - d)) ^ l;

Why is it standard practice to write formulas such as:

 Ω = (β(μ - ε))^σ

And not using descriptive names such as:

reactionSize = (timeBias * (initialValue - currentValue)) ^ userBias

Is there a practical benefit to representing concepts in such a hyper-concise way or is it more than just a long-standing convention?

submitted by /u/the320x200
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Are there any external factors (stressors) that can hasten or delay the maturing of the brain's prefrontal cortex?

Posted: 21 Sep 2016 10:52 AM PDT

From what I understand, the prefrontal cortex does not fully develop until the age of about twenty-five. So, for example, if a teenager experiences something stressful (pregnancy, war, prison), could it hasten or delay the maturing of his/her prefrontal cortex?

submitted by /u/TeaCozyDozy
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What causes the specific amount of neurotransmitters to be present in an axon terminal?

Posted: 21 Sep 2016 12:12 PM PDT

In class, we were discussing how an action potential can result in the release of inhibitory neurotransmitters (we found it perplexing that the action potential was an excitatory response that results inhibition). However, we figured out that the action potential was just releasing the neurotransmitters that were present in the axon terminal, the action potential wasn't itself an inhibitory message.

So, what is the cause of those neurotransmitters being present there to begin with? What regulates whether or not there will be a certain amount of inhibitory neurotransmitters rather than excitatory, and ect?

submitted by /u/feynmannerdfighter
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How is it that rapid fluctuations of light levels can trigger siezures?

Posted: 21 Sep 2016 07:33 AM PDT

Like when you go to a lazer light show there are trigger warnings, or whenever lights switch on and off super fast

submitted by /u/CptSnowcone
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Why are face transplants so rough?

Posted: 21 Sep 2016 10:21 AM PDT

This might seem like kind of a brash question, I don't mean it to be. It seems like with all the advances in plastic surgery, facial transplants should be more convincing than they currently are. What are the reasons it's so difficult to make a convincing facial transplant?

submitted by /u/Tom_Haley
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Are Ice Ages a phenomenon exclusive to Earth?

Posted: 21 Sep 2016 10:01 AM PDT

Since from what I understand the exact cause of Ice Ages occurring, and the fluctuations within an Ice Age itself are likely tied to the Earth's climate, would a more "stable" planet be less prone to cyclical changes like these?

submitted by /u/Sleelan
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Are drug-resistant bacteria evolving to become more immune to destruction in general, or does adaptive resistance to current drug treatments expose new vulnerabilities?

Posted: 21 Sep 2016 05:29 AM PDT

I definitely agree that the growing resistance to antibiotics is a major problem for humanity (a constant, never-ending struggle in my understanding), but hearing an expert answer this question will help me get a better grasp of how major we are talking, and I couldn't get Google to return search results that were specific enough to the question I want to explore.

To help clarify what I'm asking: In a world with countless entities competing over finite resources, it is extremely difficult (if not impossible) to gain a benefit without incurring some type of partially offsetting cost. The cost obviously doesn't completely negate the advantage gained from the benefit (because if it did then we wouldn't even notice an acquired net-benefit), but there has to be some opportunity cost to the evolved defensive mechanisms observed in drug-resistant bacteria (unless one of my assumptions is wrong).

Is the problem that we don't understand the relevant physiological mechanisms well enough yet to identify new vulnerabilities that can be exploited, or are drug-resistant bacteria evolving to become objectively less vulnerable to attack?

Thank you in advance for your time!

submitted by /u/Commodore_Obvious
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Can I have some help understanding the intuition behind Poynting's Theorem?

Posted: 21 Sep 2016 08:57 AM PDT

I understand that Poynting's theorem is basically the work-energy theorem of electromagnetics, and I understand how it's derived, but I'm having difficulty wrapping my mind around the intuition. The theorem is usually expressed in the following terms: "The amount of work done per unit time on charges by the electromagnetic force is equal to the decrease in energy stored in the magnetic and electric fields in some charge and current configuration within some volume, minus the amount of energy that flows out through a surface bounding the volume" My confusion lies in the latter half of the explanation...the bit about electromagnetic energy flowing out through the surface. This refers only to electromagnetic radiation, does it not? I realize the Poynting vector can be applied to any magnetostatic configuration to describe the direction of the flow of power, but lets say for the example of a current carrying loop of wire (for simplicity lets pretend its a superconducting wire and no energy is being lost to any sort of internal resistance and the circuit bears no load) , where the net flux of the E and B fields through the surface are zero, this cannot possibly transport energy out of the bounding surface, can it?

submitted by /u/s1gmalol
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