Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Einstein's relativity proves caloric theory?

  1. Nov 7, 2011 #1
    I am most certainly not right, though I'd like an explanation why my interpretation is wrong.

    Einstein's theory of relativity states that any body that looses energy also looses mass. Considering caloric theory states there is a fluid within every body that contains mass and transfers heat from one body to another, why wouldn't the unmeasureably small mass lost/gained in a heat transfer proccess be the caloric scientists used to talk about? Or better yet, wouldn't Einstein's relativity be a generalization of caloric theory?
  2. jcsd
  3. Nov 7, 2011 #2
    Intresting correlation but relativity doesn't say that and caloric theory is obsolete:


    For example, when a photon loses energy it does not "lose mass", nor speed for that matter. And two adjacent masses have less potential energy than two widely spaced masses....but have not "lost mass".

    Other than the fact that thermodynamic heat can change the kinetic energy of matter and energy also has gravitational effects (with mass
    and pressure) I don't know of much connection between relativity and heat.
    Last edited: Nov 7, 2011
  4. Nov 7, 2011 #3


    User Avatar
    Science Advisor
    Gold Member

    There is no actual proving or disproving involved here but you have made an interesting 'connection' between an ancient and a very modern concept.

    The temperature of a substance is certainly connected with the kinetic energy of its particles. There is a bit of a snag with trying to make to two ideas totally parallel, though. When you add energy to cause a change of state or internal Potential Energy, the caloric ideas break down a bit, I think - as they did at the time. Joule demonstrated how the caloric theory didn't account for the effects of friction etc. and brought in the idea of 'the mechanical equivalent of heat'. Relativity, of course, accounts for all this and ties up the loose ends which which caloric didn't explain.

    It's good when someone brings up something like this, though. It shows that you've been thinking. :smile:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook