4 ms·
Something the general reader may not know: As late as ~2004-7, calculations of this type were impossible. It was a major achievement when numerical relativists
by ISL 10y ago
Something the general reader may not know: As late as ~2004-7, calculations of this type were impossible. It was a major achievement when numerical relativists were able to achieve a single orbit of a black-hole black-hole binary system.
Figuring out how to make it work was the culmination of decades of attempts at the problem. Improved computational power didn't hurt, but the major improvement was finding the right metrics in which to do the simulations.
- Analemma_ 10y agoTotally unrelated to anything, but I love the term "numerical relativists". I know it's actually a branch of computational physics, but it calls to mind postmodernists invading mathematics departments and claiming that theorems are socially constructed, and that maybe 2 > 3 under a Marxist-Leninist interpretation.
- lighttower 10y agoCan you say more about the 'right metrics'? Is this some sort of transformation akin to working in spherical or cylindrical coordinate systems?
- openasocket 10y agoFrom what I remember about numerically solving differential equations, your approximations will completely diverge from the actual solution near singular points in the equation, so you have to transform the problem to come up with a singular solution. I imagine the interaction of two singularities would result in some interesting singular points. Is that what you are alluding to when you say "finding the right metrics" or am I completely off base? In either case, could you link to one of those 2004-7 papers? It sounds like a fascinating read.
- ISL 10y agoA tricky part was making sure that numerical instabilities didn't propagate outward away from the event horizon. I believe there are now several solutions to the problem, but the one I find most intuitive is simply extending spacetime ad infinitum inside the black hole in order to allow gravitational waves to propagate inward forever. More here: https://en.wikipedia.org/wiki/Numerical_relativity https://en.wikipedia.org/wiki/Numerical_relativity