Poll: A thought experiment.

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Jonluw

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May 23, 2010
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Hiya escapists.

A while back, I learned in school that photons can excite the atoms in a gas, and that those atoms will then proceed to emit photons of the same wavelength. This causes the gas to glow (provided that the photons are of a visible wavelength).

So I was thinking: What if you could encapsulate a gas - helium for instance - inside a container which, on the inside, is a perfect mirror (My physics teacher described it as White matter); and then somehow manage to excite the gas inside the container.
Would the gas continue to glow for eternity?

Edit: The Scrödinger's cat issue did bother me for a while, but I figure we should be able to predict the outcome of a situation, even if we may not investigate the outcome should the situation really occur.
 

Xpwn3ntial

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Dec 22, 2008
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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.
 

Voodoomancer

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It's impossible to answer, isn't it? If the gas is completely encapsulated in the perfect mirror, you can't see if its glowing or not, leading to a Schrödinger's cat situation.

[sub]... I think.[/sub]
 

GoldenRaz

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Mar 21, 2009
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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.
 

L4hlborg

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Well, eternity is a damn long time, but if you would somehow get your perfect mirror system to stay intact, not leak gas and have a light source in it, I think it would glow until the system is somehow broken. I might be wrong with this one, my knowledge on the subject is limited.
 

Lukeje

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Feb 6, 2008
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How are you planning on making a perfect mirror? Such a thing doesn't exist.
 

Voodoomancer

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GoldenRaz said:
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.
 

Jonluw

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Xpwn3ntial said:
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.
I didn't consider the fact that helium would eventually decay into hydrogen... But helium was just an example; let's consider the scenario if the gas was simple [sup]1[/sup][sub]1[/sub]H instead.

I'm interested in finding out how the photons would heat up the gas though.
 

Jonluw

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Lukeje said:
How are you planning on making a perfect mirror? Such a thing doesn't exist.
It's not like anyone's actually going to be able to perform the experiment. This is purely theoretical.
 

Sandernista

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Feb 26, 2009
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Yes, and no, as in: you wouldn't be able to see it. For hydrogen yes, but to such a minute degree it would be almost unnoticeable. (Then energy absorbed by the hydrogen from photons isn't that much).
 

Skorpyo

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May 2, 2010
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EDIT: Whoops! Wrong thread.

Well then, OT:

Perpetual motion is impossible. Eventually, the energy would be lost.
 

blue spartan 11

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Oct 13, 2009
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No. We will never know. Refer to the Schrodinger's cat experiment. As long as we can't see, we can't determine what is happening.
 

Xpwn3ntial

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Dec 22, 2008
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Jonluw said:
Xpwn3ntial said:
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.
I didn't consider the fact that helium would eventually decay into hydrogen... But helium was just an example; let's consider the scenario if the gas was simple [sup]1[/sup][sub]1[/sub]H instead.

I'm interested in finding out how the photons would heat up the gas though.
Assuming you don't have enough photons to make an explosion, then maybe.
 

Jack and Calumon

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Dec 29, 2008
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If you got it in a completely perfect vacuum then yes, it would stay glowing forever as that way the light will not deteriorate over distance. I'm pretty sure it's partly how Neon lights are done.

Calumon: Science makes my head hurt... :S
 

Dags90

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You wouldn't be able to excite the gas through a perfect mirror, because it'd be perfectly insulating.

Either the laws of physics apply and the question is moot, or the laws of physics don't apply and the question becomes absurd.
 

Jonluw

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May 23, 2010
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Jack and Calumon said:
If you got it in a completely perfect vacuum then yes, it would stay glowing forever as that way the light will not deteriorate over distance. I'm pretty sure it's partly how Neon lights are done.

Calumon: Science makes my head hurt... :S
Yes, it's how neon lights work; only in neon lights, the emitted photons escape from the neon-container (the tube), and the gas is excited with electricity. What I'm trying to achieve here, is that the photons do not escape, but do rather continue to "power" the gas, causing it to produce new photons to "power" it again.
 

Jonluw

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Dags90 said:
You wouldn't be able to excite the gas through a perfect mirror, because it'd be perfectly insulating.
That is indeed a problem for the practicality of the experiment; but it's irrelevant, because in this situation we're assuming that we have already somehow managed to excite the gas. The question is whether the gas would enter an everlasting cycle of excitation and emission, given the circumstances; not whether it would be possible to fulfill the circumstances stated in the experiment.
You most probably won't be able to aquire white matter either, for that matter.

Edit: I wonder though; would it be impossible for such white matter to conduct electricity?
 

Admiral Stukov

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Jul 1, 2009
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For a motherfrakking long time, yes, but nor for an eternity. We have the whole universe collapsing issue there.