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.
  • #1
Steve Rogers
9
2
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.
 
Physics news on Phys.org
  • #2
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.
 
  • Like
Likes vanhees71, Steve Rogers and Vanadium 50
  • #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.
 
  • Like
Likes vanhees71
  • #4
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?
 
  • Like
Likes vanhees71

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

What is quasi-local mass in the context of general relativity?

Quasi-local mass refers to the concept of measuring the gravitational energy contained within a finite, bounded region of spacetime, rather than at a point or over an entire spacetime. This is important in general relativity because it allows for a more precise understanding of how mass and energy are distributed and how they influence the curvature of spacetime within that region.

How does quasi-local mass differ from ADM and Bondi masses?

ADM (Arnowitt-Deser-Misner) mass and Bondi mass are measures of the total gravitational energy of a spacetime at spatial and null infinity, respectively. Quasi-local mass, on the other hand, is defined for a finite region of spacetime, providing a localized measure of gravitational energy. This makes quasi-local mass particularly useful for analyzing systems where the energy is not uniformly distributed or where the region of interest is not asymptotically flat.

Why is quasi-local mass important in understanding gravitational waves?

Quasi-local mass is important in the study of gravitational waves because it allows scientists to quantify the energy carried away by these waves from a localized region. By understanding how gravitational energy is distributed and radiated, researchers can gain insights into the dynamics of astrophysical processes, such as black hole mergers, that generate gravitational waves.

What are some common methods or definitions used to calculate quasi-local mass?

Several methods and definitions have been proposed for calculating quasi-local mass, including the Hawking mass, the Bartnik mass, the Brown-York mass, and the Wang-Yau mass. Each of these definitions has its own advantages and limitations, and they are often chosen based on the specific properties of the spacetime region being studied and the type of physical insights sought.

Can quasi-local mass be negative, and what would that imply physically?

In general relativity, the concept of negative quasi-local mass is theoretically possible, though it is typically associated with exotic matter or energy distributions that violate certain energy conditions. If a quasi-local mass were found to be negative, it could imply the presence of such exotic matter or unusual spacetime geometries. However, in most physically realistic scenarios, quasi-local mass is expected to be non-negative.

Similar threads

Back
Top