Is Spacetime Truly a Finished Block or an Open-Ended Concept?

[Joao]

Hi everyone! Sorry for the bad English!

I do understand (or at least I guess I do) that there's no universal clock and time in other worldlines may be dilated in relation to my worldline.

What I don't get is why the spacetime must be a "finished" block and not an " open ended towards the future" block.

I see that for calculations it might make no difference, I'm just wondering if that's some aspect of spacetime that shows clearly that it must be a finished block (like a thought or an actual experiment) or we just assume that it's a finished (and not growing) block.

Thanks!

 

[Dale]

What I don't get is why the spacetime must be a "finished" block and not an " open ended towards the future" block.

There is no reason. The block universe is a popular interpretation of relativity, but it is just an interpretation.

 

[Joao]

Thanks a lot Dale! =) really! =)

 

[m4r35n357]

What I don't get is why the spacetime must be a "finished" block and not an " open ended towards the future" block.

I think it makes sense for Newtonian spacetime, but is clearly incompatible with special relativity since (as you allude to) it is impossible to represent "all frames of reference" in one diagram. So, unless it can make some useful prediction that only it can give, I say let's ditch it altogether!

 

[Joao]

I think it makes sense for Newtonian spacetime, but is clearly incompatible with special relativity since (as you allude to) it is impossible to represent "all frames of reference" in one diagram. So, unless it can make some useful prediction that only it can give, I say let's ditch it altogether!

Thanks a lot for the reply! So, it's an "occam razor" situation? Since it would be simpler to do the math considering that the block universe is "complete", this solution usually is preferred over the "growing" block universe?

But in principle would be impossible to do an experiment that shows that one interpretation is more accurate then the other, as far as we know by now?

 

[Ibix]

Since it would be simpler to do the math considering that the block universe is "complete", this solution usually is preferred over the "growing" block universe?

The maths is the maths however you interpret it. It is extremely attractive to interpret it as implying the block universe, to the point that most physicists treat the block universe as "what the spacetime really is". But it's still an interpretation and does not make the maths easier or harder.

But in principle would be impossible to do an experiment that shows that one interpretation is more accurate then the other, as far as we know by now?

Correct. Although these things are occasionally subject to change - Bell managed to devise a test for local hidden variables in QM, for example, which turned that interpretation into a distinct theory.

 

[Joao]

The maths is the maths however you interpret it. It is extremely attractive to interpret it as implying the block universe, to the point that most physicists treat the block universe as "what the spacetime really is". But it's still an interpretation and does not make the maths easier or harder.
Correct. Although these things are occasionally subject to change - Bell managed to devise a test for local hidden variables in QM, for example, which turned that interpretation into a distinct theory.

Thanks a lot! It really helped me clarify this question! =)

Thanks to everyone! =)