Which term of the Einstein equation is larger?

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In summary, the discussion revolves around comparing the magnitudes of different terms in Einstein's field equations of general relativity, specifically focusing on how the curvature of spacetime interacts with energy and momentum. The analysis often highlights the dominance of the stress-energy tensor term in scenarios involving massive bodies, while other terms may become significant in extreme conditions such as near black holes or during cosmic events.
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TL;DR Summary
How different terms of the Einstein equation are important?
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https://en.wikipedia.org/wiki/Einstein_field_equations

If we study when the sun bent the light of the stars behind it, which above terms have the largest influence, and which can be neglected? (I think that the third term can be neglected for such phenomena.)

And what changes when we are close to a small black hole?

Probably the first and the second terms have different visualizations and meanings?

Probably these answers can be related to Baez's paper https://arxiv.org/pdf/gr-qc/0103044?

Probably they can be related also to Carroll's paper https://arxiv.org/pdf/gr-qc/9712019?
 
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Kinetic energy is ##m(v_x^2 + v_y^2 + v_z^2)/2##. Which term is largest?
 
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I don't think your question has an answer of the sort that you're looking for.
You are right that the ##\Lambda## term is negligible in the situations you are considering. Also the right-hand side of the equation is zero in these cases, which pretty much requires that the two ##R## terms are always the same size. But...

1) That's not one equation. ##\mu## and ##\nu## take on values from zero to three, so we're looking at a compact representation of 64 different equations (although because of various symmetries it's really just 2010).
2) The various terms in any one of those ten equations don't add to produce the light-bending effect. The overall shape of the spacetime is described by the metric tensor ##g_{\mu\nu}## which you see in the equation so these equations determine the value of the various components of that tensor.
3) These are differential equations - both ##R## and ##R_{\mu\nu}## are complicated functions of the derivatives of the various ##g_{\mu\nu}## values.

You've quoted two good sources, but you might be better off starting with https://preposterousuniverse.com/wp-content/uploads/2015/08/grtinypdf.pdf

[Edited to correct "20" to "10"]
 
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As was explained, cosmological term of ##\Lambda## be zero here. Once you have gotten metric tensor ##g_{\mu \nu}##, pass of light or geodesic is derived by its definition. So you should investigate how to get Schwartzshild metric ##g_{\mu \nu}## which tells us gravity around the celestrial body, which is BH or star does not matter. You may find in textbooks that Einstein equation in vaccum space where lights travel, ##R_{\mu \nu}=0##, and Newton's gravitation law as approximation are used for its derivation.
 
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Λ is zero...unless it's not.

Further, even if non-zero, it is negligible in most cases....but not all.

This is really unanswerable in the sane way my earlier message is unasnwerable.
 
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Nugatory said:
we're looking at a compact representation of 64 different equations
16, not 64. Given your existing correction I guess you were thinking of the Riemann tensor, which does have 64 components of which 20 are independent.
exponent137 said:
If we study when the sun bent the light of the stars behind it, which above terms have the largest influence, and which can be neglected?
In that case you'd be thinking of vacuum solutions, and the whole thing reduces to ##R_{\mu\nu}=0##, which you'd solve for ##g_{\mu\nu}##.

But if you're interested in gravitational lensing you'd probably already have the solution to this in mind, the Schwarzschild or Kerr metrics depending on how important the angular momentum of your lensing object is (negligible for the Sun, but maybe not for a black hole). You'd be interested in the geodesic equations, which describe the paths of free-falling objects in spacetime.
 
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exponent137 said:
If we study when the sun bent the light of the stars behind it, which above terms have the largest influence, and which can be neglected?
In the case you describe, all of the terms are zero.
 
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Nugatory said:
the right-hand side of the equation is zero in these cases, which pretty much requires that the two terms are always the same size.
No, it requires that (if we assume the ##\Lambda## term is negligible) both Ricci terms are zero. The simplest way to see this is to transform to the trace reversed form of the equation, which shows that we must have ##R_{\mu \nu} = 0## if ##T_{\mu \nu} = 0##.
 
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PeterDonis said:
No, it requires that (if we assume the ##\Lambda## term is negligible) both Ricci terms are zero. The simplest way to see this is to transform to the trace reversed form of the equation, which shows that we must have ##R_{\mu \nu} = 0## if ##T_{\mu \nu} = 0##.
Yes, that stronger statement is also true.
 
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FAQ: Which term of the Einstein equation is larger?

What are the main terms in the Einstein equation?

The Einstein equation, also known as the Einstein field equations (EFE), is a set of ten interrelated differential equations in general relativity. The main terms include the Einstein tensor (G), the stress-energy tensor (T), and the cosmological constant (Λ). The equation can be expressed as G = 8πGT/c^4 + Λg, where G is the gravitational constant, T is the stress-energy tensor, and g is the metric tensor.

How do we determine which term is larger in the Einstein equation?

To determine which term is larger in the Einstein equation, one must analyze the physical context and the specific situation being considered. For example, in regions of strong gravitational fields, such as near black holes or neutron stars, the Einstein tensor (G) can be significantly larger than the stress-energy tensor (T). In contrast, in the vacuum of space far from massive bodies, the cosmological constant (Λ) may become more significant.

Does the size of the terms change with different cosmic scales?

Yes, the size of the terms in the Einstein equation can change dramatically with different cosmic scales. On galactic scales, the stress-energy tensor associated with matter and energy density is often the dominant term. However, on cosmological scales, especially in the context of the expanding universe, the cosmological constant (Λ) may play a more prominent role, influencing the dynamics of cosmic expansion.

What role does the cosmological constant play in determining the size of the terms?

The cosmological constant (Λ) represents the energy density of empty space, or dark energy, and it can have a significant impact on the dynamics of the universe. In the current understanding of cosmology, the cosmological constant is considered to be a major contributor to the accelerated expansion of the universe. Its value can make it larger than the stress-energy tensor in certain cosmological models, particularly at large scales.

How does the presence of matter affect the terms in the Einstein equation?

The presence of matter affects the terms in the Einstein equation primarily through the stress-energy tensor (T). Matter and energy contribute to the curvature of spacetime represented by the Einstein tensor (G). In regions with high matter density, such as near stars or galaxies, the stress-energy tensor can be much larger than the cosmological constant, leading to significant gravitational effects. Conversely, in regions with low matter density, the cosmological constant may dominate.

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