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Relativity on an Atomic Scale

  1. Sep 4, 2009 #1
    Can you think about relativity in terms of the motions of atoms as they are subject to intermolecular forces? Is time moving slower for the atom which is accelerating with respect to another? Or, would the macroscopic averaging negate the individual motion of the atoms?

    Or, is this a ridiculous question to be asking?
  2. jcsd
  3. Sep 4, 2009 #2


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    The determining factor is velocity. When an object is hot the molecules it consists of move faster. The molecules in the highest accuracy time measuring devices are cooled to close absolute zero. (The main reason for that, I think is to make the spectrum as narrow as possible)

    Acceleration of molecules relative to each other does not elicit relativistic effects; it's relative velocity that counts. When molecules in a sample have (averaged over time) a larger velocity than the lab it is located at, then for those molecules less proper time will elapse than for the lab.

    A very, very farfetched scenario (but in principle possible):
    You have a sample of a radio-active isotope with a short half-life, and you want to prolong the life of the sample. Heat it up to plasma temperature and beyond, and if you get it so hot that the nuclei reach relativistic velocities the life will be significantly prolonged. Containing that plasma might be tricky, though.

    Last edited: Sep 4, 2009
  4. Sep 4, 2009 #3


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    There are relativistic effects at the atomic scale, but not in ways that you are thinking of. Relativistic corrections for high atomic orbitals, such as the d and f orbitals, are routinely considered. Furthermore, why do you think http://math.ucr.edu/home/baez/physics/Relativity/SR/gold_color.html" [Broken]?

    Last edited by a moderator: May 4, 2017
  5. Sep 4, 2009 #4
    Absolutely you can think about relativity when looking at a collection of atoms that feel forces (you *generally* have to also deal with quantum mechanics too). Anyway, even if a macroscopic object is just sitting on a table, the atoms are moving with respect to each other, so they will indeed each have their own Lorentz frame: They will not generally agree on distance and time measurements of events they might witness, which includes seeing time dilation. However, as mentioned in the previous post, the non-relativistic approximation is often good enough for these situations because the relative speeds of the atoms are not high enough. Inside the atom, relativistic effects become very important, though.
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