Energy density in Stress Energy Tensor

In summary, energy density in the stress-energy-tensor refers to the amount of energy stored in a system per unit mass, with T00 representing the energy density. In a 4x4 matrix, the time dimension is typically numbered as 0 instead of 4. Energy density can be mathematically defined as energy per unit volume.
  • #1
shounakbhatta
288
1
Hello,

I am new to this, if somebody could help me:

The energy density in stress-energy-tensor is the amount of energy stored in a given system per unit mass. The T00=energy density.

In a 4x4 matrix, we generally start with 1,1. Why it is 0,0?

Secondly, what does energy density mean mathematically? I am unable to get over the concept.

Thanks,

-- Shounak
 
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  • #2
It's common (but not universal) to number the time dimension as 0 instead of 4 (x, y, and z or other spatial directions would be 1-3). It doesn't make a big difference either way.

Energy density = energy per unit volume.
 
  • #3
Ok, thanks a lot.
 

Related to Energy density in Stress Energy Tensor

1. What is energy density in the stress energy tensor?

Energy density in the stress energy tensor is a measure of the amount of energy per unit volume stored in a given region of space. It is a component of the stress energy tensor, which is a mathematical object used in the theory of general relativity to describe the distribution of energy and momentum in space-time.

2. How is energy density in the stress energy tensor calculated?

The energy density in the stress energy tensor is calculated by taking the time-time component of the tensor and dividing it by the square of the speed of light. This gives the amount of energy per unit volume in a given region of space.

3. What is the significance of energy density in the stress energy tensor?

Energy density in the stress energy tensor is significant because it is related to the curvature of space-time according to Einstein's field equations. It also plays a crucial role in understanding the behavior of matter and energy in the universe, particularly in the study of gravitational fields.

4. How does energy density in the stress energy tensor relate to dark energy?

Energy density in the stress energy tensor is thought to be the source of dark energy, which is a hypothetical form of energy that is believed to be responsible for the accelerating expansion of the universe. Some theories suggest that dark energy may be related to the vacuum energy density of the stress energy tensor.

5. Can energy density in the stress energy tensor be negative?

Yes, energy density in the stress energy tensor can be negative in certain situations. This is due to the fact that the stress energy tensor can have components that represent both energy (positive) and momentum (negative). In general relativity, negative energy density can contribute to the overall curvature of space-time.

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