Poll: A thought experiment.

[Casimir_Effect]

Assuming you know what's going on inside then it depends on your definition of "glow". Photons will bounce around, get absorbed by electrons, and get emitted afterwards. But they will be emitted with a large range of frequencies depending on their energy, which will depend on a load of factors in itself. So if you define glow as you would an ember, ie. visible light being given off. Then typically no it won't glow forever. The 2nd law of thermodynamics requires that the system eventually reaches an equilibrium where the energy is spread evenly throughout the volume. The energy of a photon in this ensemble will not be in the visible wavelength region - unless the system was VERY energetic to begin with (initial conditions are the key to this gedanken experiment) - and any atomic excitations of the gas will not be of large enough magnitude to be followed by a continuous emission of higher, visible-band photons. Even if you allow for the occasional 2 or 3 photon absorption, this will be a rare occurance and so can not be called a continuous glow. In fact the human eye wouldn't even see/register it.

Short-answer: No, unless the amount of energy in the gas (ie. its temperature) is insanely high to begin with. But even then I'm not totally sure. The amount of energy required could be enough to increase the mass of the system to an amount greater than the Schwarzschild radius of the container, resulting in a black hole. The only thing that escapes from that is Hawking radiation, which you definitely can't see. This sort of problem is stupid. I need number to work things out. And motivation. And it's fucked the length of my pithy, short answer.

 

[GoldenRaz]

I doubt it. Wouldn't some of the light be converted into heat energy even though there are those perfect mirrors? Granted, my knowledge in physics is rather limited, but that's the first thing that comes to mind.

Well, that's just IR radiation then, isn't it. And if it's a perfect mirror, it will deflect that as well.

Sure, but if all the light is converted into heat, then that would mean that there's no more light and instead a lot of IR radiation. Which would mean that yes, the gas would eventually stop glowing.

But then again, since no energy is lost, wouldn't the IR radiation just cause the gas to be excited again?
Gah, this is complicated...

Another thought: this perfect mirror material, does it 'reflect' everything? Even the motion caused by the atoms colliding with it?
'Cause if it doesn't, some energy would disappear that way, causing the container to either vibrate or to heat up.

 

[GoldenRaz]

Gosh dang it to heck, I double posted.
Do ignore this to the best of your abilities.

 

[Lord Kloo]

With an unlimited supply of photons and energy this is theoretically possible however getting unlimited power/energy sources is very difficult..

 

[Veret]

To the people saying perpetual motion makes this impossible, consider the following:

A satellite is in a perfect orbit around the Earth. There is nothing it its way, no forces of friction (however negligible) or any other interference. According to Newtonian physics, it will remain in orbit--and therefore in motion forever. But it is also useless to us; if we try to harness this object's kinetic energy for use elsewhere, it will slow down and fall out of orbit. This is why the concept of "perpetual motion" is impossible: It seeks to harness an infinite source of energy. The glowing container is just like the satellite; it can keep going forever, but we can't ever do anything with it.

More on conservation of energy:

No. Eventually it would become particle soup and the helium would decay into hydrogen and deuterium with traces of tritium. The photons themselves would heat up this gas and cause the pressure inside to build up and eventually explode.

It couldn't explode. We aren't allowing any energy into the system (that is, the container and its glowing contents), because that would defeat the purpose of the experiment. Similarly, the magical mirror isn't letting any energy leave the system either, so we know that the total energy in the container is going to be exactly the same eleventy billion years from now as it was when we first started. If it didn't have enough energy to blow up then, how could it ever?

As for the actual answer to the original question, I...have no idea. Maybe? Given the impossible nature of the experiment, and Schrodinger factor, I really wouldn't know where to begin.

 

[gerbil234]

No. when a photon hits an electron it will cause the electron to become excited, jump to a higher energy orbital, and then let out the same frequency light when it jumps back down. However, we also have atoms in this gas, and when a photon hits an atom it is absorbed as heat energy. Heat is actually a measure of the kinetic energy of the molecules, not infrared radiation. So basically what would happen is eventually the glow would die out, but the gas would be hotter.

EDIT: Infrared radiation is also light, just not visible light. All radiation is a part of the electromagnetic radiation spectrum. The reason we use infrared to detect hot objects (like bodies) in the dark is because infrared light is so low energy that pretty much everything emits it at some level (just like steel will glow orange when it is hot enough, we will glow infrared at body temperature). An infrared display just "translates" the light into the corresponding energy pattern in the visible light spectrum for us (high energy infrared is shown as white, and low energy as red in many cases).

 

[thiosk]

It will not glow for ever. When light is absorbed, and then reemitted, the molecules are left in a different vibrational state--- that is, they're hot now. That energy is pulled away from the emitted photons, lowering their energy. For a true atomic gas, theres other mechanisms at work as well which make this not work for eternity, but now that I'm writing, I really should go back and take another look at that book on physical chemistry I have on that dusty shelf.

Your idea for the mirrored tube is in fact the basic principle behind an Integrating sphere [http://en.wikipedia.org/wiki/Integrating_sphere] which is a spectroscopic tool used for a few applications.

 

[Insanum]

Whenever someone posts a question like this, i always ask one back:

Does it matter?[/I]

No, that wasn't a poor science joke. I cant say i understand fully what you mean, but i dont think you can get a "perfect mirror", and so questions like this are pointless.

Same with a lot of philosophy - "If a tree falls...blah blah" - Does it honestly matter?

 

[Horseradish_5000]

While entropy will mean that the material used to create the capsule will eventually decay. Surely while the inner surface remains to be a "perfect mirror" no energy can escape the capsule. Therefore the gas shall eventually reach an equilibrium with photons being emitted and absorbed by the gas and if that equilibrium can sustain illumination the gas will continue to glow forever while the mirror is intact.

Though I hope that the mirror would be 2 way because if it can absorb energy but never emit it, that would be bad wouldn't it?

 

[Jonluw]

Whenever someone posts a question like this, i always ask one back:

Does it matter?[/I]

No, I'm pretty sure it doesn't matter. I think it's entertaining to think about stuff like this though. And in my mind; if it's entertaining, that validates my doing it.

Besides; does anything really matter?

 

[TheYellowCellPhone]

Sounds too much like a perpetual motion machine.

This guy does have a good point. Thinking of that, I do think it's impossible to last forever.

 

[Habakkuk]

Hang on a minuit, if we're thinking on a quantum level, doesn't that mean that it could potentialy last fo ever and not last forever at the same time?

 

[Insanum]

Whenever someone posts a question like this, i always ask one back:

Does it matter?[/I]

No, I'm pretty sure it doesn't matter. I think it's entertaining to think about stuff like this though. And in my mind; if it's entertaining, that validates my doing it.

Besides; does anything really matter?

Well asking redundant questions may not be what i call a form of entertainment, And i think a lot of philosphy is a lot of tosh, but thats just my opinion (honestly, (this isnt directed at the guy who quoted me btw) I couldn't give two shits if anyone quotes me telling me "im wrong[/I]").

Yes, Things matter. It depends entirely on perspective - If you look at the Grand Grand scheme of the universe, Perhaps we do not matter, the same way the fate of a small colony of ants in the middle of the jungle does not matter to us, However when you consider the exact scientific reason we are all here (and by that, i mean how you were concieved) and the fact that we're all here to do exactly that; somewhere[/I].

Anyways, Its Just gone midnight, im too tired & annoyed to explain anymore.

<color=white>Wonder how many people will still tell me im wrong, or ask smart arse retorhical questions like "oh, well if its a load of old tosh i guess you thing is a waste of space" and "You're an idiot, did you know that?" To these people i refer to my earlier statement.

 

[Jonluw]

No. when a photon hits an electron it will cause the electron to become excited, jump to a higher energy orbital, and then let out the same frequency light when it jumps back down. However, we also have atoms in this gas, and when a photon hits an atom it is absorbed as heat energy. Heat is actually a measure of the kinetic energy of the molecules, not infrared radiation. So basically what would happen is eventually the glow would die out, but the gas would be hotter.

I actually didn't consider the possibility that photons might hit the nuclei rather than exciting the electrons.

So what you're saying is that if a photon hits a protium (since I decided a while back that we'd be using protium rather than helium, so we wouldn't have to worry about decay) nucleus, the energy from the photon will be turned into heat?
Interesting. So we'd possibly end up with a container full of hot hydrogen, rather than glowing hydrogen.

 

[Jonluw]

Whenever someone posts a question like this, i always ask one back:

Does it matter?[/I]

No, I'm pretty sure it doesn't matter. I think it's entertaining to think about stuff like this though. And in my mind; if it's entertaining, that validates my doing it.

Besides; does anything really matter?

Well asking redundant questions may not be what i call a form of entertainment, And i think a lot of philosphy is a lot of tosh, but thats just my opinion (honestly, (this isnt directed at the guy who quoted me btw) I couldn't give two shits if anyone quotes me telling me "im wrong[/I]").

Yes, Things matter. It depends entirely on perspective - If you look at the Grand Grand scheme of the universe, Perhaps we do not matter, the same way the fate of a small colony of ants in the middle of the jungle does not matter to us, However when you consider the exact scientific reason we are all here (and by that, i mean how you were concieved) and the fact that we're all here to do exactly that; somewhere[/I].

Anyways, Its Just gone midnight, im too tired & annoyed to explain anymore.

<color=white>Wonder how many people will still tell me im wrong, or ask smart arse retorhical questions like "oh, well if its a load of old tosh i guess you thing is a waste of space" and "You're an idiot, did you know that?" To these people i refer to my earlier statement.

What I was getting at was that it doesn't matter that it doesn't matter. Why should the fact that something I'm having fun with doesn't matter bother me?

Edit: Well, it's too late in the night for me as well in any case.

 

[Wrists]

If all of the energy from photons emitted is returned to excite electrons to higher energy levels, then yes it could continue to emit light. As long as we agree that it could never work in practice, it could work in theory.

 

[beniki]

To the people saying perpetual motion makes this impossible, consider the following:

A satellite is in a perfect orbit around the Earth. There is nothing it its way, no forces of friction (however negligible) or any other interference. According to Newtonian physics, it will remain in orbit--and therefore in motion forever. But it is also useless to us; if we try to harness this object's kinetic energy for use elsewhere, it will slow down and fall out of orbit. This is why the concept of "perpetual motion" is impossible: It seeks to harness an infinite source of energy. The glowing container is just like the satellite; it can keep going forever, but we can't ever do anything with it.

This isn't a Newtonian problem though, but rather a quantum mechanics one. And even given your example, given an infinite amount of time the satellite would still degrade. Essentially tiny bits of material, be it wave radiation or eve whole atoms would break off eventually. It'd take forever, but nothing stays the same for eternity.

Although I'll admit that if the object was a solid lump of zero energy material, in a perfect orbit around a perfect gravitational mass, in a zero state of acceleration or decceleration... then a giant purple elephant would still randomly appear to knock it out of orbit

 

[Veret]

This isn't a Newtonian problem though, but rather a quantum mechanics one. And even given your example, given an infinite amount of time the satellite would still degrade. Essentially tiny bits of material, be it wave radiation or eve whole atoms would break off eventually. It'd take forever, but nothing stays the same for eternity.

Although I'll admit that if the object was a solid lump of zero energy material, in a perfect orbit around a perfect gravitational mass, in a zero state of acceleration or deceleration... then a giant purple elephant would still randomly appear to knock it out of orbit

Sorry, I should have clarified. The example I gave wasn't supposed to be a real satellite; it's a theoretical one that's not subject to everything you just listed. Hence, nothing in its way, no friction, etc. Clearly, we both know that such an ideal object--while completely impossible--would hypothetically orbit forever until it collides with Bertrand Russell's eponymous teapot somewhere between Earth and Mars, then mysteriously transfigures itself into a room-temperature superconductor. Point being, this is clearly a theoretical situation and we should just roll with it.

After pondering the problem a little longer, though, I think most of the EM radiation in the gas would eventually be converted into thermal/kinetic energy, since that's how these things usually end up. I think.