High School Questions about Einstein and the Block Universe

[Quantum Alchemy]

I find this subject fascinating. Einstein said the distinctions between past, present and future is just a persistent illusion. I was watching a special with Brian Greene and other Physicist who think we do live in a Block Universe and they explained it very well. Here's my question.

Say there was a hypothetical alien race at point x which would be at a distance where any signal they sent us today(present) would reach us in 1980. They would get information about our atmosphere and what music we listen to but from 1980 just like when we observe planets from Earth we're seeing them as they were in the past.

My question is, could they send a signal to us in 1980 today and would that mean 1980 is a point in space-time that still exists and a new worldine would occur different than ours where we made alien contact in 1980 or if there was a signal sent we would have heard it in 1980 but how would that work in the context of the block Universe?

 

[Nugatory]

We do not allow threads and questions about the block universe model, for the reasons described here so this thread is closed. More focused questions are of course welcome - you won't find a bunch of people more committed to exlaining relativity anywhere else on the internet.

My question is, could they send a signal to us in 1980 today and would that mean 1980 is a point in space-time that still exists and a new worldine would occur different than ours where we made alien contact in 1980 or if there was a signal sent we would have heard it in 1980 but how would that work in the context of the block Universe?

The quick answer is "no". To get a signal to us in 1980 they would have had to send it before 1980 (if they are X lightyears away and the signal travels at the speed of light, then at time 1980-X) and of course they can't discover anything about us in 1980 until after 1980+X when light from Earth in 1980 has reached them).

But please be aware that I have glossed over some serious problems around how we and the aliens could be using the same calendar even though we're in very different places. To form an accurate picture you'll want to understand the relativity of simultaneity and the notion of spacelike and timelike intervals; we can recommend some good starting points.