Questions about the vacuum

Discussion in 'Physics & Math' started by Magical Realist, Oct 7, 2012.

  1. Magical Realist Valued Senior Member

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    Is the space in between atoms a vacuum? Why not? Also, is the temperature of a perfect vacuum absolute zero? How can it not be?
     
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  3. eram Sciengineer Valued Senior Member

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    i think electron orbitals fill those spaces.

    Not including all that QFT, electromagnetic radiation does contribute to the temp of a vacuum. There is no place in this universe that is at abs zero, for that would be thermodynamically impossible.
     
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  5. Magical Realist Valued Senior Member

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    I see. Would photons and neutrinos also qualify as "fillers" that negate a perfectly vaccuous space? As far as infrared radiation, what is it heating up if there are no atoms around to be heated up anymore? Can heat exist in pure nonmaterial field-like form like light does?
     
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  7. Neverfly Banned Banned

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    http://en.wikipedia.org/wiki/Vacuum_energy
     
  8. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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    Maybe we should start by defining what "vacuum" means. My guess is that you have a non-technical definition in mind, which simply won't suffice when talking about quantum mechanics.

    Categorically, "vacuum" doesn't mean "empty". This is a classical definition that, like so many other classical definitions, doesn't survive quantum intuition. Of course, "temperature" is another classical word that has a bit of a different meaning in quantum mechanics.

    I've forgotten most of the QFT that I used to know, but I would say that vacuum means the absence of real particles. This doesn't mean that virtual particles may not be present: for example, if your universe consists of two atoms of opposite charge, the universe will be populated with virtual photons that are emitted by one atom and absorbed by the other---virtual photons mediate electromagnetism. So even though the universe is empty, apart from the two atoms, any little corner of the universe (which doesn't contain the atoms) will still contain virtual photons. To complicate matters, you can have vacuum-to-vacuum transitions: this means a virtual electron-positron pair is produced from the vacuum, and eventually annihilate back into the vacuum. This effect is real, and can be measured.
     
  9. eram Sciengineer Valued Senior Member

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    Do QFTs explain why fundamental particles can decay into one another?
     
  10. OnlyMe Valued Senior Member

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    QFT — Quantum Field Theory, predicts how they will decay, but I don't think it actually explains why, at least not fundamentally why.
     
  11. eram Sciengineer Valued Senior Member

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    this is the bizarre idea behind particle physics, though it seems like the only explanation.
     
  12. alansteve777 Registered Member

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    Yes,

    I think same. The space between atoms should fill with electrons. Electron is not a particle it is charge density means all the charge is not concentrated at once.
     

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