Math of relativistic mass different from that of rest mass ?

[koti]

To do that we would have to get into details like what are other constituents of alloy..

"The density of steel varies based on the alloying constituents but usually ranges between 7750 and 8050 kg/m3"

https://en.wikipedia.org/wiki/Steel

(not to mention it varies with temperature/pressure)

Being pedantic is an important feature for someone who tries to mingle with thought experiments like these but, common Besides, we already ditched the steel ball idea and went with Strange's alien abducted moon instead.

 

 

They won't. But, apparently, working out exactly what the gravitational effect of a moving object would be is non-trivial. Whenever this has come up on forums in the past the consensus view of those experts who could do the relevant math was always, "its complicated".

Strange...although the geometries become difficult due to "additional" energies I presume it is mathematicaly doable and there are no open questions as to how gravity behaves in these situations or is that not entirely accurate? Edited May 6, 2017 by koti

[imatfaal]

Analytic solutions of the Einstein Field Equations are pretty few and far between. We have them for the vacuum around the various sorts of black holes - which we can then use to approximate (sometimes very closely) other situations.

 

I do not know if - for example - if the black hole merger spotted by ligo was predicted by a solution to the equations or through massive modelling; I think it was the later.

 

So to answer your last question; yes solutions exist, but whilst we understand the tools with which to find the solution we do not yet have the skill to utilise them. Instead of solving the equations within a certain set of parameters we create models / simulations and run them a myriad of times to find out what should happen.

[Strange]

Yep, black hole mergers require massive simulations to understand their behaviour.

[imatfaal]

Yep, black hole mergers require massive simulations to understand their behaviour.

 

I don't think we even have a solution for close binary star system - and it was the loss of angular momentum (via gravitational waves) in a close binary that was the first indirect evidence of a new prediction of GR

[koti]

Are we dealing here with a similar math and probability complexity as in the case of strings where I've seen numbers like 10^-600 of how many possible solutions there are to string equations?

I wasn't aware that ligo might have been solely basing on modeling, I was convinced that gravity waves have to be inevitable as they are an intrinsic part of Einstein's equations.

I started this thread to get a better grip on where we currently are on gravity. I have some knowledge but I have obvious gaps in understanding of gravity. I don't want this to deviate into QM where the inconsistencies become definite but I want to understand where my and our gaps are exactly. The more I dig into this subject, the more I get a feeling that I'm looking at gravity as a point object from a distance where in fact when you get closer to that point, it is actually 3D object with texture and complexity previously not observable from a distance. I know I'm deviating here with this analogy into philosophy but I couldn't find a better way of explaining my concerns. I mean...couldn't it be that what we observe with GR and SR are just aproximations of some bigger picture as far as gravity is concerned?