Gravitational Effect from Relativistic Mass: Answers & Questions

[stefanbanev]

TL;DR Summary

Does relativistic mass make a proportional gravitational effect on observer it flies by?

Does relativistic mass make a proportional gravitational effect on observer it flies by? Does 1 ton (resting 1 ton) of lead moving relatively observer at some speed close enough to C may appear as a micro black hole? What abort Hawking radiation in this case? Does it mean that we may convert any mass to energy via Hawking radiation simply by speeding up such mass fast enough? How relativistic mass contributes to total mass of observable universe? ~13.8+ billion light years away any proton must have ~infinite mass relatively Earth' observer; does it meant that universe has an infinite mass relatively Earth' observer?

 

[Ibix]

Does relativistic mass make a proportional gravitational effect on observer it flies by? Does 1 ton (resting 1 ton) of lead moving relatively observer at some speed close enough to C may appear as a micro black hole?

No. Speed is relative. You are currently moving at 0.999999c relative to a high energy cosmic ray, so according to it you have a huge relativistic mass. Do you feel like a black hole?

How relativistic mass contributes to total mass of observable universe?

It doesn't. The concept doesn't translate simply to the case of curved spacetime, even if one persists in using it in special relativity.

This kind of misconception is one of the reasons that relativistic mass has been a deprecated concept for decades. Popsci sources have not caught on, sadly.

 

[Ibix]

...that said, with a lot of caveats, a mass moving relative to you does deflect your path more than a naive Newtonian calculation would suggest. The last time this came up, @pervect suggested:

the Olson and Guarnio paper, "Measuring the active gravitational mass of a moving object ",

I believe you get up to a factor of 2 "greater mass" from something approaching the speed of light. This is not relevant to your cosmological example.

 

[pervect]

Summary: Does relativistic mass make a proportional gravitational effect on observer it flies by?

Does relativistic mass make a proportional gravitational effect on observer it flies by?

It winds up having more than a proportional effect, if one measures the effect by the velocity induced by the relativistic flyby. See for instance Olson, D.W.; Guarino, R. C. (1985). "Measuring the active gravitational mass of a moving object". In the ultra-relativistic case, the moving mass induces nearly twice as much veloicty change as a slower-moving object with the same energy . ( Energy a synonym for relativistic mass that I greatly prefer to use).

Does 1 ton (resting 1 ton) of lead moving relatively observer at some speed close enough to C may appear as a micro black hole?

No. Whether an object is a black hole or not is a different question than asking how much velocity a relativistic flyby induces in an observer. Being a black hole is a frame-independent property, so an object that is not a black hole in it's rest frame is not a black hole in any frame.

What abort Hawking radiation in this case? Does it mean that we may convert any mass to energy via Hawking radiation simply by speeding up such mass fast enough? How relativistic mass contributes to total mass of observable universe? ~13.8+ billion light years away any proton must have ~infinite mass relatively Earth' observer; does it meant that universe has an infinite mass relatively Earth' observer?

The accretion disk of a black hole radiates much of the energy of infalling matter away before the matter reaches the black hole, without any need for hawking radiation, which is a tiny quantum effect.

Basically, as dust falls into the black hole, it speeds up, and collisions between the dust particles heat them up, causing them to radiate energy away.

To do this to an object effectivel, one might have to break it up into pieces, first, so the pieces can hit each other.

The "mass of the observable universe" isn't really well defined. One could come up with a coordinate dependent figure by insisting that one use the standard cosmological coordinates, but one wouldn't get the same number in other coordinates.

 

[stefanbanev]

... without any need for hawking radiation, which is a tiny quantum effect.

"Tiny" for normal BH not for micro BH. The BH with 1-ton of resting mass would evaporate in seconds (if not microseconds), converting all its mass into energy with 100% of efficiency. Well, it would be a quite spectacular manifestation of "tiny" effect ;o)

Regarding to ultra fast non-zero-mass particles with speed above some C*0.99999999999... threshold which may make such particles heavy enough to make a noticeable tide-effect on observer, long before that it becomes a femto/yocto-BH which evaporates. So, it implies that the energy/speed for non-zero-mass particles has an upper limit because of Hawking radiation. Pls correct me if I'm wrong...

 

[PAllen]

Something moving ultrareletivistically relative to you does not appear like or become a BH. Full stop. Your whole premise is simply false.

 

[PeterDonis]

Something moving ultrareletivistically relative to you does not appear like or become a BH. Full stop. Your whole premise is simply false.

And with that, this thread is closed.