Scientists begin modelling universe with Einstein’s full theory of general relativity

One hundred years after Einstein introduced general relativity, it remains the best theory of gravity according to researchers in this field, consistently passing high-precision tests in the solar system and successfully predicting new phenomena such as gravitational waves, which were recently discovered by the Laser Interferometer Gravitational-Wave Observatory.

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CrazyNeutrino said:

Scientists begin modelling universe with Einstein’s full theory of general relativity

One hundred years after Einstein introduced general relativity, it remains the best theory of gravity according to researchers in this field, consistently passing high-precision tests in the solar system and successfully predicting new phenomena such as gravitational waves, which were recently discovered by the Laser Interferometer Gravitational-Wave Observatory.

more…

> The equations of general relativity, unfortunately, are notoriously difficult to solve.

They are? I hadn’t heard that. I’ve had a look at the top of the following two equations from GR, and that didn’t look too difficult, because now excellent methods are available off-the-shelf such as TVD/Van Leer/MUSCL/Minmod/Roe (see https://en.wikipedia.org/wiki/Flux_limiter). I’ve used them myself.

mollwollfumble said:

> The equations of general relativity, unfortunately, are notoriously difficult to solve.

They are? I hadn’t heard that. I’ve had a look at the top of the following two equations from GR, and that didn’t look too difficult, because now excellent methods are available off-the-shelf such as TVD/Van Leer/MUSCL/Minmod/Roe (see https://en.wikipedia.org/wiki/Flux_limiter). I’ve used them myself.

I think the difficulty of the equations of general relativity go beyond what a numerical solution can do. For example, the solutions to the simplest Einstein equation:

G_uv = 0

include not only flat spacetime but also an arbitrary number of non-spinning and/or spinning uncharged blackholes. It is worth noting that although the Schwarzschild solution was obtained shortly after Einstein published general relativity, the Kerr solution with its slightly lower symmetry took considerably longer to obtain.