2.5 Gravitational Wave Astrophysics
Discussion

September 30, 2019 at 12:43 pm
Numerical relativity is a field of study that attempts to produce approximate numerical solutions to the Einstein field equations for various astrophysical situations, like black hole mergers. Until recently this was a very difficult task, with programs crashing well before they produced meaningful results. What do you think of the fact that Einstein wrote these equations but himself could not solve them except in greatly simplified cases?

August 19, 2020 at 5:09 am
Well, just try to solve the complete (!) equations by hand and you’ll see pretty soon that you’ll run into problems. Even with numerical relativity it took some time and more sophisticated technology (both hard and software) to finally come to some templates which are solutions of individually defined merging black holes. More templates, including neutron stars and mixed versions (BH – NS) and a larger bandwith of the involved masses are yet to come.

August 19, 2020 at 10:59 am
Yeah I think Gravitational Waves are the new astrophysical window to what we think as the Cosmos. Dear World Science U, I have questions for the Experts, these are here
1. How can Gravitational Waves tell us about the existence of Extra Spatial Dimensions and of indeed Strings in String Theory??
2. We need a theory for Quantum Spacetime and a sophisticated theory of Quantum Gravity, my point is that I study Loop Quantum Gravity so how Gravitational waves can be described by Loop Quantum Gravity??
3. Why a Gravitational Wave will fail to escape the Event Horizon of a Black Hole??
4. If a Gravitational Wave will fail from escaping a Black hole, then how we observed those Gravitational waves. 
August 20, 2020 at 10:31 am
Philosophically, has one to be able to solve self written equations? I think no as there are equations without solution, at this time.

August 24, 2020 at 1:43 pm
The fact that he couldn’t solve the equations, although he wrote them, exemplifies how far ahead of himself he was. Even in his assumed errors, Einstein was correct. I respect the boldness and courage he exemplified in his work and thoroughness before publishing.

August 25, 2020 at 5:27 am
The gravitational waves are generated from a point in space just outside the combined event horizon when the two black holes emerge, hence the waves can escape. Nothing that is generated within the combined event horizon can escape. Given that all the mass of each black hole is concentrated at its centre, the event horizon is not an actual physical surface – it is simply a region in space. Hence, when the two event horizons of the colliding black holes merge into one, the central masses of each black hole must still be moving towards each other. Do they continue to spiral inwards towards a final merger? Presumably so, but we will never detect gravitational waves from that part of the collision.

September 1, 2020 at 8:15 am
It seems to me that he did not have the facilities that we have now to be able to solve those equations

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