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Laser in a box

  1. Jul 8, 2010 #1
    If you could build a box with a reflective inside that no light could escape. If somehow you put a laser in the box and fired the beam and then shut off the laser what would happen? Would the beam continued to bounce off of the insides of the box or would the beam dissipate somehow? If it does dissipate, where does the light go without an escape point?

    I personally think that it would dissipate, I don't however have a clue where the energy goes. It becomes a different form of energy obviously, but what... got me.
  2. jcsd
  3. Jul 8, 2010 #2
  4. Jul 8, 2010 #3
    Makes sense. So heat then would be the end of the life cycle for light. If heat is the result of the expenditure of light, wouldn't it make sense then that Cold, or the absence of heat would be the result of the expenditure of heat? If so we could theorize that the cold throughout the universe is the result of this process?

    An interesting question this brings up is, does Cold in itself have an undiscovered life cycle that possibly initiates the heat life cycle (cosmic perpetual motion?)?

    Another would be on the other side of the spectrum, could this mean that once all the fuel is used, no more universe?
  5. Jul 8, 2010 #4
    Heat is (usually atomic) motion.
    The concept of cold as a corollary is of no mathematical use.

    Look up entropy - that's of more use to you as a concept here.
  6. Jul 8, 2010 #5
    Then the universe as we know it is limited to amount of fuel it has to use (matter). We began as noting and based on this we will end as nothing? Interesting idea.
  7. Jul 8, 2010 #6
    I don't totally buy that because I don't really believe in time but I'm willing to agree that it's a part of the puzzle.
  8. Jul 8, 2010 #7


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    1] The walls are not 100% reflective; some of the light will go into the walls and rfadiate as heat.
    2] There is a laser in the box that has parts that are not reflective. They will very quickly absorb stray light and heat up.
  9. Jul 8, 2010 #8


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    This does not follow.
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