General Relativity

Firstly, I’ll start off by saying that I don’t know anything about this theory. I do know that it states that mass curves spacetime, and acceleration is due to the apparent motion of particles along that line.

Einstein Field Equations

$G_{\mu \nu }+\Lambda g_{\mu \nu }=\kappa T_{\mu \nu }$

I will have to question:

• What is the abstract of this theory?
• What is $G$?
• What is $\mu$?
• What is $\nu$?
• What is $\Lambda$?
• What is $g$?
• What is $\kappa$?
• What is $T$?

Answers

• $G_{\mu \nu }$ is the Einstein tensor
• $g_{\mu \nu }$ is the metric tensor
• $T_{\mu \nu }$ is the stress-energy tensor
• $\Lambda$ is the cosmological constant
• $\kappa$ is the Einstein gravitational constant

Now I have to ask:

• What is a tensor? A: A tensor is a multidimensional array of numbers, in the order o
• What is the Einstein tensor?
• What is the metric tensor?
• What is the stress-energy tensor?
• What is the cosmological constant?
• What is the Einstein gravitational constant?

Answers

• The Einstein tensor is a tensor defined as $G_{\mu \nu }=R_{\mu \nu }-\frac{1}{2}{g}_{\mu \nu }R$
  • It is also known as the trace-reversed Ricci tensor (or Ricci curvature tensor)
  • It is used to express the curvature of a pseudo-Reimannian manifold

Now I have to ask

• $R_{\mu \nu }$ is the Ricci curvature tensor
• $R$ is the scalar curvature