General relativity isn't the be all and end all, Google unification.
No theory is the 'be all and end all' of anything, general relativity can be proven wrong at any time and replaced by a new understanding, however those are just words - actually doing that is another thing altogether.
That is brilliant and says everything I wanted to say.
You've got people like ma & you who believe intelligent life is very rare and more than likely didn't happen in the same period as us (Fermi Paradox) and then you've got others who think we look like the Headquarters scene in Men In Black.
For me the Fermi Paradox is the one which I find most plausible, I think it's reasonable to believe that the universe probably is packed with life of some sort or another, some of it intelligent and some of it highly-advanced, to the point we might not recognise it as life. However, intelligence would logically denote an element of curiosity - a species can't really become intelligent, or knowledgeable without being curious about it's place in the universe.
It would also make sense, that some of those civilisations would have existed for tens, to hundreds of millions of years - in that time they'd develop technology and infrastructure that we can't even imagine, all the time being fuelled by curiosity and a desire to expand, so where is everybody?
If it's possible to make a physics breakthrough (wormholes, anti-gravity, FTL, teleportation, time-travel, etc) those discoveries would logically be the result of the species in-built curiosity, because you don't just stumble upon those sorts of things by accident.
If it were true, there could be tens or hundreds of millions of civilisations who could posses such technology, and to me it seems that our planet would stand out, and so you'd think it would be reasonable that a species with technology and curiosity would have paid us a visit at some point.
Maybe those physics breakthroughs
are literally impossible, maybe (it's a sobering thought) that there are millions of civilisations out there who will all burn out and die before meeting one another.