Heat flow components of Stress/Energy Tensor

  • Thread starter Thread starter TerryW
  • Start date Start date
  • Tags Tags
    Heat flow Physics
TerryW
Gold Member
Messages
222
Reaction score
20
Homework Statement
Show that the Trace of the Heat Flux Stress/Energy Tensor is zero
Relevant Equations
T(heat) = q^i u^j + u^i q^j
I'm pretty sure I understand why q^i u^j + u^i q^i is the stress component (i \neq j) of the Heat Flux Stress/Energy Tensor but I can't think of, or find any explanation for why q^i u^i + u^i q^i = 0.

I found one reference in Lightman, Press, Price and Teukolsky - Problem Book in Relativity and Gravitation which just says
"Since q^α u_α = 0 (heat flux is spacelike in comoving frame)" but what does that really mean from a physics point of view?

Can anyone help?TerryW

PS - Preview doesn't seem to be working at the moment
 
Last edited:

Thread 'Initial conditions for orbits around a wormhole'

Hi, I had an exam and I completely messed up a problem. Especially one part which was necessary for the rest of the problem. Basically, I have a wormhole metric: $$(ds)^2 = -(dt)^2 + (dr)^2 + (r^2 + b^2)( (d\theta)^2 + sin^2 \theta (d\phi)^2 )$$ Where ##b=1## with an orbit only in the equatorial plane. We also know from the question that the orbit must satisfy this relationship: $$\varepsilon = \frac{1}{2} (\frac{dr}{d\tau})^2 + V_{eff}(r)$$ Ultimately, I was tasked to find the initial...
View full post »

Thread 'Help to convert units of a simple formula'

The value of H equals ## 10^{3}## in natural units, According to : https://en.wikipedia.org/wiki/Natural_units, ## t \sim 10^{-21} sec = 10^{21} Hz ##, and since ## \text{GeV} \sim 10^{24} \text{Hz } ##, ## GeV \sim 10^{24} \times 10^{-21} = 10^3 ## in natural units. So is this conversion correct? Also in the above formula, can I convert H to that natural units , since it’s a constant, while keeping k in Hz ?
View full post »

Similar threads

Heat Flow Through a Truncated Cone
Replies
3
Views
4K
I do not understand stress energy tensor for fluids
Replies
6
Views
2K
Transforming Stress-Energy Tensors in Different Frames
Replies
5
Views
3K
A Thermal stresses in the stress tensor
Replies
4
Views
871
Stress-energy tensor for a rotating sphere
Replies
1
Views
3K
I Question about Stress-Energy Tensor: A First Course in GR
Replies
8
Views
2K
Chemistry Show that book levitation by absorption of heat violates 2nd law
Replies
13
Views
2K
Continuum mechanics, physical interpretation of terms in balance eq.
Replies
9
Views
2K
What Are the Steps to Solve Faraday Tensor and Index Notation Problems?
Replies
22
Views
3K
How Is Heat Flow Calculated in a Constant Temperature Quasistatic Process?
Replies
14
Views
3K

Hot Threads

Recent Insights

Back
Top