What happens to light trapped in a closed sphere?

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Discussion Overview

The discussion revolves around the behavior of light trapped in a closed, perfectly reflective sphere. Participants explore the implications of light's persistence within the sphere after the light source is removed, questioning whether the light remains visible or dissipates over time. The conversation touches on theoretical physics concepts and the nature of light in a confined space.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant, Mau, questions whether light remains visible in a closed sphere after the light source is removed, suggesting that it may continue to bounce around inside the sphere.
  • Mau compares the scenario to turning off lights in a room, wondering where the light goes if it cannot escape the sphere.
  • There is speculation about whether the light could be converted into heat or energy upon interaction with the sphere's walls, likening it to a bouncy ball losing energy when it hits the ground.
  • Another participant suggests that the light may ultimately be absorbed by the reflective surfaces of the sphere.
  • Participants express uncertainty regarding the fate of the light and whether it behaves differently than light from distant stars that reaches Earth.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the light remains visible or what happens to it after the light source is removed. Multiple competing views and uncertainties persist regarding the nature of light in this scenario.

Contextual Notes

The discussion includes assumptions about the properties of the sphere and the behavior of light, which may not be fully explored or defined. There are unresolved questions about the conversion of light to heat and the implications of light's behavior over time.

Who May Find This Useful

This discussion may be of interest to those exploring theoretical physics, particularly in relation to light behavior, energy conversion, and the implications of closed systems.

Mau
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Light's 'Life'

Hello everybody:
Let me first introduce myself. I am a Sophomore in High School that has a self-found interest in theoretical physics. I have never taken a formal physics class and I have only learned bits and pieces from random shows on PBS, readings on the Internet, and a few books. This means that my logic will probably be flawed somewhere because I only know a little bit - I have also made a few conclusions through my own thinking that may have been proven otherwise. I enjoy thinking about mind teasers and problems of the sort.

So, to get back to my reason for this post: I am interested in light and it's 'life.' I had an interesting problem enter my mind when I was thinking in looking back in time by going faster than light (theoretically impossible, I know).

The scenario is as follows: let us say that person A is inside a perfect sphere with a radii of 10m. The sphere's surface area is light, sound, radio proof - nothing can escape or get in. Now, we place a really bright light source in the sphere so that it lights up the entire sphere. Now, for some reason or another, the light source goes away extremely fast (in less than one nanosecond). The question on my mind is wether the sphere remains bright or goes dark?
The light cannot escape, so it cannot go anywhere and it must remain inside the sphere. It can defuse (I believe light gets wider the further it goes - like a flash light), but it'll just end up bouncing around in the sphere.

So what happens? To me it seems like that it would stay bright, but if I lock myself in my basement and then turn off the lights it goes dark. The light has to go somewhere. Where does the light go?

However, what if you replaced that light source with a some sort of gas. The gas would stay in the sphere and it could be detected depending on the type of gas.
The thing that troubles me the most is that when you put light from other stars into the picture. This light is traveling possibly thousands of light years and it still reaches our planet without turning into something else. How is this any different from the light just bouncing around in a 10m sphere?

If anyone could provide any insight to this question then that would be fantastic! It's a problem that has haunted my mind for a while now and I'm seeking an answer.

Thank you very much in advanced!
- Mau

P.S - If I have posted this in the wrong forum, feel free to move it.
 
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Thank you very much for that reply. It was a thought that had crossed my mind, but for some reason or another, I ignored it. :-)

One question remains: where does the light go? Does it become heat / energy? I am picturing light falling into a wall similar to how a bouncy ball falls towards the ground. As it keeps bouncing, it loses it's GPE and it's converted into heat stored into the ground (I believe I have that right).

Also, I'm sorry if this thread seems like a re-post of the one linked above. I had trouble searching for my question--there are no good keywords that I could think of.

- Mau
 
Welcome to PF, Mau, but when exactly did I say that you could move in with me?
Oh well... I guess there's room enough for both of us in the Zone, but you're going to have to pay half the rent.:biggrin:
 
Danger said:
Welcome to PF, Mau, but when exactly did I say that you could move in with me?
Oh well... I guess there's room enough for both of us in the Zone, but you're going to have to pay half the rent.:biggrin:
So this is what teachers mean by attention to details ;) :)
 
Right. And quit hogging the blankets.
 
GENIERE said:
Oh c'mon I was going to post that!

Mau said:
where does the light go? Does it become heat / energy? I am picturing light falling into a wall similar to how a bouncy ball falls towards the ground. As it keeps bouncing, it loses it's GPE and it's converted into heat stored into the ground (I believe I have that right).
I think all the light ends up getting absobed into the mirror.
 

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