Question about Relatavistic mass

  • Context: Undergrad 
  • Thread starter Thread starter DHF
  • Start date Start date
  • Tags Tags
    Mass
Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
4 replies · 1K views
DHF
Messages
247
Reaction score
32
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?
 
Astronomy news on Phys.org
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.