Thanks to Barry Evans for the nice piece on General Relativity ("General Relativity, 100 Years On," Nov. 19). He has it right except perhaps for one part that may well be changing as of late. He states (and this has been the generally accepted view for the last 100 years) that "the space-time fabric extends, unbroken, throughout the entire universe."
Now, however, there is a controversial but more and more likely scenario, called "Firewall Theory," first proposed in 2012, that the spacetime manifold is likely broken at the surface of a black hole. Here is how it's been described by a couple of the heavy hitters:
Raphael Bousso of UC Berkeley muses that space and time seem to "somehow" end at the horizon. And Joseph Polchinski at UC Santa Barbara sums it up this way: "The inside of a black hole — it may not be there. ... Probably that's the end of space itself; there's no inside at all."
If the idea proves correct, it means that black holes are literally cavitation bubbles (holes) in the spacetime manifold possibly (my speculation) caused by the rapid expansion of the early universe. Think of what happens when you pop open a carbonated drink.
Douglas George, Eureka