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Given the energy momentum tensor of a mass in a general frame, how does one derive the energy momentum tensor in the rest frame?

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  • $\begingroup$ Are you asking about the energy-momentum $4$-vector $p^{\mu}$? or the stress-energy tensor $T^{\mu \nu}$? $\endgroup$ – Triatticus May 27 '18 at 3:17
  • $\begingroup$ I meant $T_{\mu\nu}$ $\endgroup$ – physics_2015 May 27 '18 at 5:27
  • $\begingroup$ There is no guarantee that such a frame exists. Its existence depends on what you mean by "a mass." $\endgroup$ – Ben Crowell May 27 '18 at 14:25
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In the rest frame the momentum vanishes. The momentum density is $T^{i0}$ and the total momentum is the space integral of this. You need to find the Lorentz transformation that makes this quantity vanish.

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  • $\begingroup$ OK. Thanks. So, if I understand correctly, one has to transform the energy-momentum tensor to a one which has zero elements except $T_{\mu}0$. If so, how does one Lorentz transform $T_{\mu\nu}$? $\endgroup$ – physics_2015 May 27 '18 at 9:18
  • $\begingroup$ That is not what I wrote. You need the transformation for which $\int{dV T^{i0}} =0$. $\endgroup$ – my2cts May 27 '18 at 9:30

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