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Particle vs energy frames

by bloby
Tags: energy, frames, particle
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bloby
#1
Feb7-12, 10:50 AM
P: 112
Hello.

Is there a way, as for the energy frame, to get the particle frame 4-velocity of a fluid from its energy-momentum tensor?
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Bill_K
#2
Feb7-12, 01:15 PM
Sci Advisor
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Bill_K's Avatar
P: 4,160
Well, you could look for a timelike eigenvector.
bloby
#3
Feb7-12, 03:11 PM
P: 112
Could you explain why?

Bill_K
#4
Feb7-12, 04:09 PM
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Bill_K's Avatar
P: 4,160
Particle vs energy frames

Quoting Wikipedia: "For a fluid in thermodynamic equilibrium, the stress-energy tensor takes on a particularly simple form
Tαβ = (ρ + p/c2)uαuβ + p gαβ where uα is the fluid's four-velocity."

And clearly uα is an eigenvector.
bloby
#5
Feb7-12, 06:01 PM
P: 112
Ok, but for a fluid out of equillibrium?
Bill_K
#6
Feb7-12, 06:13 PM
Sci Advisor
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Bill_K's Avatar
P: 4,160
Sorry, I misunderstood. In that case I don't know the answer. Maybe you need to be given more information than just the stress-energy tensor.


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