Question about Relatavistic mass

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Discussion Overview

The discussion revolves around the concept of relativistic mass, particularly in the context of objects moving at relativistic speeds. Participants explore whether the increase in mass is a real physical quantity and its implications for gravitational effects, as well as the relationship between mass, energy, and inertia in the framework of relativity.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions whether the mass gained by an object moving at relativistic speeds is "real" and if it would exhibit gravitational effects similar to a star if it attained such mass.
  • Another participant suggests that the answer to the "real" nature of mass depends on the definition of "real," asserting that it is measurable like any other quantity.
  • It is noted that in General Relativity (GR), gravity is not solely derived from mass but from the stress-energy tensor, indicating that the gravitational influence of the probe could vary based on circumstances.
  • Participants discuss the notion that the increase in mass in relativity serves as a measure of energy and inertia, rather than a direct measure of gravitational influence.

Areas of Agreement / Disagreement

Participants express differing views on the nature of relativistic mass and its implications for gravitational effects, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

The discussion touches on the definitions of mass and energy in relativity, the role of the stress-energy tensor in GR, and the implications of these concepts for understanding gravitational interactions, but does not resolve the complexities involved.

Who May Find This Useful

This discussion may be of interest to those studying relativity, gravitational theory, or the conceptual foundations of mass and energy in physics.

DHF
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I am trying to get my head abound something and I am hoping you guys can shed some light on this for me.

When discussing objects moving an relativistic speeds, its often mentioned that as an object approaches the speed of light, it gains mass.
My question is: is this mass real? If you somehow managed to impart enough energy on a probe to move it fast enough that it has the mass of a star, would that probe have the same gravitational pull of a star? Or is the increase in mass simply something we use to discuss how much kinetic energy the object contains?
 
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DHF said:
My question is: is this mass real?

That depends on the definition of "real". It is as real as any other measurable quantity.

DHF said:
If you somehow managed to impart enough energy on a probe to move it fast enough that it has the mass of a star, would that probe have the same gravitational pull of a star?

There is no reasonable answer because the source of gravity in GR is not mass (no matter which kind of mass) but the stress-energy-tensor. Depending on the circumstances the probe can have the gravity of a stars or not.

DHF said:
Or is the increase in mass simply something we use to discuss how much kinetic energy the object contains?

In relativity it is in fact a measure of the energy. In it's original meaning it is a measure of the inertia.
 
Thank you very much for the clarification.
 
Thank you, reading it now.
 

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