Einstein-Hilbert Action Derive from Christoffel Symbols and Quadratic Lagrangians?

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In summary, Landau's book "Classical Field Theory" demonstrates how the Einstein-Hilbert action can be obtained by integrating by parts and using the divergence theorem. This leads to a Lagrangian that is quadratic in the metric and its first derivatives. By imposing the constraint \mathcal{g}+1 =0, the Lagrangian becomes quadratic in the derivatives and fields and can be evaluated using a Functional integral. However, the last formula presented in the conversation is not clear and may need to be edited.
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Kevin_spencer2
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In Landau's bok "Classical Field Theory" pages: 372-373-374 they manage to get the Einstein-Hilbert action (after integrating by parts and use divergence theorem)

[tex] \mathcal L = \int dx^{4} \sqrt (-g) g^{ik}(\Gamma^{m}_{il}\Gamma^{l}_{km}-\Gamma^{l}_{ik}\Gamma^{m}_{lm}) [/tex]

from this and definition of 'Chrisstoffel symbols' the Lagrangian would be quadratic in the metric and its first derivatives , if we impose the constraint:

[tex] \mathcal{g}+1 =0 [/tex] (does it has any physical meaning??)

and a Qadratic Lagrangian in the derivatives and fields can be evaluated by means of a Functional integral.
 
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Please clean up and edit. The last formula makes no sense.
 

1. What is Einstein action?

Einstein action is a mathematical concept developed by Albert Einstein in his theory of general relativity. It is a mathematical expression that describes the curvature of space-time caused by the presence of matter and energy.

2. How does Einstein action relate to general relativity?

Einstein action is a fundamental component of general relativity. It is used to describe how the presence of matter and energy affects the curvature of space-time, which in turn determines the motion of objects in that space-time.

3. Can you explain the equation for Einstein action?

The equation for Einstein action is S = ∫R√-g d^4x, where S is the action, R is the Ricci scalar curvature, g is the determinant of the metric tensor, and d^4x is the volume element. This equation is used to calculate the total action of a system, which is related to the curvature of space-time.

4. How does Einstein action differ from Newton's laws of motion?

Einstein action and Newton's laws of motion are two different ways of understanding the behavior of objects in the universe. Newton's laws describe the motion of objects in a flat, non-curving space-time, while Einstein action takes into account the curvature of space-time caused by matter and energy.

5. What are some practical applications of Einstein action?

Einstein action has many practical applications, such as understanding the behavior of objects in strong gravitational fields (such as near black holes), predicting the motion of planets and other celestial bodies, and helping in the development of technologies such as GPS systems.

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