Linked Questions

0
votes
1answer
131 views

The significance of the pressure term within the momentum-energy tensor [duplicate]

EDIT: this question is based around my notion regarding the possible role of potential energy in the momentum energy tensor T$_{\mu\nu}$, The answer below resolves the question and I have deleted ...
0
votes
1answer
171 views

In General relativity, what is the meaning of flow of $x$ momentum in $x$ direction or pressure in $x$ direction? [duplicate]

I found this interesting paper on Arxiv devoted to explaining Einstein's field equations in simple English. The author, JC Baez, does this by considering a group of small spherical balls in ...
1
vote
0answers
88 views

What are the dimensions of the stress energy tensor in relativity? [duplicate]

Can anyone tell me what the dimension of the stress energy tensor is? Also, if it represents energy density, will calling it kinetic or potential energy be appropriate?
2
votes
0answers
60 views

What component of the stress–energy tensor contains the kinetic energy of heat? [duplicate]

As I understand it, the component $T_{00}$ of the stress-energy tensor contains the energy density (which equals the mass density), $T_{0i}$ are the impulse flows (intuitively speaking, the velocities)...
0
votes
0answers
36 views

How are mass and density treated in general relativity? [duplicate]

Background: I am confused by how mass relates to the equations in general relativity. For example, given a certain mass density distribution, I am unsure how to express a system in terms of GR. ...
27
votes
7answers
3k views

Paradox regarding phase transitions in relativistic systems

The main question I would like to ask is whether quantities such as density are dependent on the frame of reference. I have searched several forums and the answer is somewhat controversial. Some ...
15
votes
1answer
5k views

What is the stress energy tensor?

I'm trying to understand the Einstein Field equation equipped only with training in Riemannian geometry. My question is very simple although I cant extract the answer from the wikipedia page: Is the ...
1
vote
1answer
2k views

Can heat energy be transformed into gravitational potential energy? [closed]

I was wondering it it could be done. I know that Heat is just kinetic energy due to vibration of molecules but is it possible for this transformation of energy?
4
votes
1answer
679 views

Components of the stress energy tensor

I am confused about what the components of the stress energy tensor actually represent and how they are representative of energy in spacetime. I have seen multiple questions on here, and have re-read ...
1
vote
1answer
528 views

Diagonal Stress-Energy Tensor

What does it mean if the stress-energy Tensor ($T_{ij}$) is a diagonal matrix? (i.e. the only nonzero components are density energy $T_{00}$ and pressure $T_{11}$, $T_{22}$, $T_{33}$). What can we ...
1
vote
1answer
682 views

Which form of Einstein's stress-energy tensor $T$ is physical, the covariant or the contravariant?

Using Einstein's Field Equations for a specific metric I am interested in, I have calculated the first diagonal term of the stress energy tensor $T$, which is the energy density. In my calculations, ...
1
vote
1answer
243 views

Does Newton's third law remain totally unchanged even in Einstein's theory?

Why Newton's third law remain unchanged still now in relativity theory (as for example that is why we feel weight due to equal but opposite reaction of the Earth's surface)?
1
vote
1answer
198 views

What exactly is a Stress-Energy tensor?

I am very new to physics and have recently come across the term stress-energy tensor. I am completely clueless as to what this is, and the Wikipedia page seems to confuse me even more. Can someone ...
1
vote
2answers
186 views

How does the general relativity describe the pressure?

The general theory of relativity describes the gravity as a geometrical feature (in very twisted geometry). That's comprehensible to me when the motion occurs and "the most straight" trajectory is to ...
2
votes
4answers
216 views

Visualization of $ dtdx$ and $dxdy$ term in metric tensor

For the sake of simplicity, lets take a 2+1 dimensional spacetime. Lets take the metric $$ds^2 = g_{tt}dt^2 + g_{xx}dx^2 + g_{yy}dy^2 + g_{tx}dtdx + g_{xy}dxdy$$ What is the visualization or ...

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