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Heat without mass?

  1. Sep 30, 2011 #1
    In "Into the Universe with Stephen Hawking," when describing the early universe prior to, and seconds after the start of TBB, Hawking says it was an ultra hot 'fog' of energy. No light yet existed, so no IR radiation, and no mass existed until the energy cooled down and formed nearly equal amounts of subatomic particles and their 'anti' counterparts.

    I don't understand how it could be "hot" if there was no mass and no light. Isn't heat basically just the sum kinetic and potential kinetic energies of the mass in a system?
    Last edited: Sep 30, 2011
  2. jcsd
  3. Sep 30, 2011 #2


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    Light is only as small and relatively low-energy section of the EM spectrum. I doubt the early universe had any EM below gamma rays.

    It was far too hot for matter to form. Matter did not condense out of energy until after tens of thousands of years of cooling.

    But the early universe was packed wall-to-wall with high energy photons, making it very hot indeed.
  4. Sep 30, 2011 #3


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    I think the OP's question was relating to the nature of temperature, which is defined as the average kinetic energy of particles. If there are no particles, there no temperature strictly speaking, just energy density.
  5. Oct 1, 2011 #4
    Exactly. So no one has answered my question. How can it be "ultra hot" when it has no matter?
    Is Hawking just making eroneous statements because he's trying to dumb it down to laymen terms?

    On a side note;
    the same program stated the "Milky Way is 6,000 billion miles wide."
    6,000 billion miles = 6 trillion miles. That's approximately one lightyear. He's off by an order of 100,000. Nice editing.
    Last edited: Oct 1, 2011
  6. Oct 1, 2011 #5
    well heat is energy related to the vibrations in the particles of matter, but energy can be traveled through light, to my knowledge. It has to do with radiation I think. Maybe you should refer to Neil Borh's model the the hydrogen to get a better understanding. I'm a bit confused myself on this matter. I'm just suggesting that energy can travel through light at that constant speed which creates heat on matter. I'm not sure though. I went over this type of stuff breifely, but you need to take at least a few weeks for serious study to understand this stuff I think. well, it may just take a few days, but the point is that it's not easy to understand.
  7. Oct 1, 2011 #6
    I find this very interesting to think about. this may be a bit off topic but a guy with last name leplace suggested that the planets were formed due to gas condensing. I'd like to believe that was false, because I've thought about the begining of the solar system in terms of the sun being something completely different that exploded and created a bunch of matter that litterally expanded and then traveled back to the sun, because of the sun's gravity and only the planets were left, because each individual gravitational force the planets exerted canceled out with one another, allowing a solar system to work.
  8. Oct 1, 2011 #7
    I'm not clear on what you're trying to state Raybesto, but as far as I've ever seen all forms of radiation are created by matter and it's actions and decay. Which stills leaves me asking "how" can there be heat, let alone radiation, without mass.
    BTW I understand subatomic particles have mass but are not "matter," so my question uses the term mass.
  9. Oct 1, 2011 #8
    you should read about niels bohr. He explained that energies are converted through photons I think. Then Plank expanded on it, etc.
  10. Oct 1, 2011 #9
    I'm saying that a photon of light carries energy at the speed of light and is conserved which heats matter. where heat is the energy of the vibrations of the particles and atoms.
  11. Oct 1, 2011 #10
    As I originally wrote, I agree with that definition of heat, and as I quoted Hawking of saying, the early U had no particles nor atoms. Only an "ultra hot fog of energy."
  12. Oct 1, 2011 #11
    Yea but if heat is due to the radiation of energy traveling at the speed of light, then the "ultra hot fog of energy" is radiation that can be converted into heat where "hot" might simply be a suggestion that the energy has a big potential for heat. You should ask like a physics teacher about this too. They may give other answers then you could come up with your own! :)
  13. Oct 1, 2011 #12
    It seems we're stuck on light and radiation, but as I've pointed out, Hawking stated that, "...in the early U there was no light and no matter." And radiation is created by actions of particles of matter and their decay.
  14. Oct 1, 2011 #13
    yea this is a stumper for me. haha
  15. Oct 1, 2011 #14
    im sure it all boils down to the big bang theory one way or another. lol
  16. Oct 1, 2011 #15


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    twisted, I answered this in post 2.

    "Light" is very low energy. The EM spectrum has no upper bound. There would have been forms of EM with energy levels the likes of which will never again be seen in our old, cool dark universe.

    They are energy. Energy is heat.
  17. Oct 1, 2011 #16


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    That's quite an error. It's interesting to note however that up until recently the British used one billion to denote 10^12 as opposed to Americans 10^9. So if he was talking about the thickness of the universe he may have been correct (otherwise still out by a factor of 100).
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