Probing General Relativity's Limits

 

think it would be great to come up with ideas that people were still trying to improve upon in a century. 

That is the situation with Einstein's structure of ideas, especially the general theory of relativity.

Physicists are probing its limits not in the hope that they can somehow over come it and erase it from the blackboard of history -- that won't happen --but in the expectation that in time somebody will do to Einstein what he did to Newton. Roughly speaking, Einstein showed that Newton was right about a special case within a broader situation. Outside of this special case (a stable framework for observations, within which objects move at slow velocities) things work in non-Newtonian ways.

Could even Einstein's understanding of physics turn out to be a special case within a broader situation. It is almost certain that this WILL happen. The question is: where do the Einsteinian rules break down? Find that out, and come up with the broader theory, and your name my friend will be as immortal as both Ike's and Bert's. 

Some of the work of Hawking and Penrose gives us an idea of how this might happen to some lucky still unspecified physicist. Their deductions from Einsteinian principles tell us that the black hole horizon is not a physical thing. It is a point beyond which nothing returns. But it is like a "city limits" in space. Not a physical thing like a castle's walls. 

But maybe Einstein (in terms of the inferences rigorously drawn from his premises) is wrong. Maybe there is something physical. 

If he is wrong, then maybe this border that black holes have will turn out to create echoes. Waves -- specifically gravitational waves -- might bounce right off of it. This is a hypothesis that a number of people are testing, among them Niayesh Afshordi of the Perimeter Institute.

The scientists postulating a sort of wall around a black hole did report a signal that sounded like an echo of a gravitational wave generating event in August 2017. Other scientists say that the Permeter Institute has misunderstood its data, and there was no true echo. The dispute will likely continue for some time yet. 

I'm not going anywhere special with this but this idea of grey-bearded geniuses debating the echoes of gravitational waves and, implicitly, the limits to general relativity, is fascinating to me.

Like, wow, man....