Quasi-local mass as a measure of the gravitational energy?

In summary: In general relativity, gravitation is seen as a consequence of the curved spacetime instead of a force in classical mechanics. If so, how can we talk about its energy without considering it as a force field?In summary, the conversation discusses the topic of quasi-local mass or quasi-local energy and questions why it serves as a measure of gravitational energy. It also raises the issue of how to talk about gravitational energy in the context of general relativity, where gravity is viewed as a result of curved spacetime rather than a force.
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Steve Rogers
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TL;DR Summary
How can we talk about the gravitational energy without considering it as a force field?
I'm self-studying the mathematical aspects of quasi-local mass, or quasi-local energy (e.g. Hawking energy), and a fundamental question has been lingering in my mind for a long time: why does quasi-local mass provide us with a measure of the gravitational energy? In general relativity, gravitation is seen as a consequence of the curved spacetime instead of a force in classical mechanics. If so, how can we talk about its energy without considering it as a force field? Thank you.
 
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Steve Rogers said:
quasi-local mass, or quasi-local energy
Please give a specific reference for where you are getting this from. Without a specific reference we do not have a valid basis for discussion.
 
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  • #3
PeterDonis said:
Please give a specific reference for where you are getting this from. Without a specific reference we do not have a valid basis for discussion.
Hello, a quick reference for this topic can be found on arXiv, as follows.
https://arxiv.org/abs/1510.02931

I guess the term "quasi-local mass" is more familiar to people working on mathematical relativity or mathematical physics, such as Shing-Tung Yau and Robert Geroch.

Thank you for replying.
 
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Steve Rogers said:
a quick reference for this topic can be found on arXiv, as follows.
Thanks for the reference. Can you point out which particular part of it is the basis for your question?

Steve Rogers said:
why does quasi-local mass provide us with a measure of the gravitational energy?
 
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1. What is quasi-local mass?

Quasi-local mass is a measure of the gravitational energy contained within a finite region of space, rather than at a single point like the traditional concept of mass. It takes into account both the mass and the energy of the gravitational field within that region.

2. How is quasi-local mass different from traditional mass?

Traditional mass is a measure of the amount of matter contained within an object, while quasi-local mass takes into account the gravitational energy associated with that matter. This means that the quasi-local mass of an object can change depending on its location and the surrounding gravitational field.

3. What is the significance of quasi-local mass in general relativity?

In general relativity, quasi-local mass is important because it allows us to understand the gravitational energy contained within a finite region of space. This is crucial for understanding the dynamics of objects in the presence of strong gravitational fields, such as black holes.

4. How is quasi-local mass measured?

There are several different methods for measuring quasi-local mass, including the use of geometric quantities such as the area and circumference of a surface, as well as the use of physical quantities such as the energy density of the gravitational field. However, these methods are still being developed and refined.

5. Can quasi-local mass be negative?

Yes, it is possible for quasi-local mass to be negative. This can occur in certain situations, such as when the gravitational energy of a region is greater than the mass contained within it. However, negative quasi-local mass is still a topic of ongoing research and its implications are not yet fully understood.

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