Is the popular view of the block universe accurate?

  • #1
Buckethead
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I have an image of the block universe that is probably similar to how many people view it, as a 4D non dynamical construct where the "present" is a slice of this block and this slice moves forward from the past to the future. Furthermore, depending on your relative velocity, your slice may be at an angle relative to someone else's slice visually demonstrating relativity of simultaneity. Because one person can have a "present moment" that can be both before and/or after another persons present moment, we are left with the impression that we exist at each and every instant of time in this block. Not just as a ghostly image but as a conscious aware entity. This to me clearly cannot be the case otherwise I would be aware of every instant of time which I most certainly am not.

The other problem with the block universe is the implication that time travel into the past is possible and I also think that is a bit of a stretch (just my opinion)

Is there a more accurate or more refined interpretation of relativity of simultaneity that seems a little more logical or realistic? I recognize that the block universe is really only a semi useful interpretation, probably designed to be entertaining for science programs, but certainly relativity of simultaneity does demand some kind of interpretation and it just doesn't seem like the block universe picture is a very good one.
 

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  • #2
Nugatory
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Your understanding is about as good as it gets.

Block universe is not experimentally testable, so there's no way of saying whether it's right or wrong. If using that model makes you more comfortable with relativity of simultaneity then you're free to use it; if not, you can ignore it.

Because we can't say whether it's right or wrong, and because we're tired of moderating threads that can never be settled, we generally discourage discussions of it:https://www.physicsforums.com/insights/pfs-policy-on-lorentz-ether-theory-and-block-universe/
 
  • #3
Ibix
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Not just as a ghostly image but as a conscious aware entity. This to me clearly cannot be the case otherwise I would be aware of every instant of time which I most certainly am not.
The point is that your conciousness now (or at least your brain now) is a slice through the 4d structure. The same is true of (for example) a ball. The ball now doesn't react to everything on its worldline. Its worldline is shaped by events in its causal past, and will be affected by events in other parts of spacetime. Why would your brain be any different? Please be aware of PF rules on speculative posts if you're going to posit some kind of non-physical nature to the mind.
The other problem with the block universe is the implication that time travel into the past is possible and I also think that is a bit of a stretch (just my opinion)
The block universe does not imply this. There are solutions to the equations of general relativity that allow crossing one's own worldline, yes, but those exist whether or not you interpret them as implying a block universe. And "I personally do not like the implications" is not a reason to reject a theory. Or not a good reason, anyway.
Is there a more accurate or more refined interpretation of relativity of simultaneity that seems a little more logical or realistic?
The problem you have is that any interpretation is based on the same maths. Any implications following from any interpretation are therefore either the same as the block universe or an add-on that is not part of the theory.
 
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  • #4
Nugatory
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but certainly relativity of simultaneity does demand some kind of interpretation
Does it? The reason you're looking for an interpretation is that you have a hidden assumption: that "A's time coordinate is greater than B's time coordinate" implies that A happened after B in some physically reasonable sense. It doesn't - it tells us something about the coordinate system you're using. To get a physically meaningful statement, something that has observational consequences, we have to have a timelike worldline between A and B.
 
  • #5
Buckethead
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Thanks for the reply. I read your link before I posted and at the time thought my question was quite different, but upon re-reading it, I see it is painfully close to violating this rule. My intention was to determine if behind closed doors while drinking wine if physicists ever discuss more interesting interpretations of relativity of simultaneity than the public is aware of (over and above LET or BU). Considering all the gazillions of interpretations in quantum mechanics I found it interesting that there have been no new interpretations of relativity of simultaneity. Again, thanks for your reply and my apologies.
 
  • #6
Buckethead
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Does it? The reason you're looking for an interpretation is that you have a hidden assumption: that "A's time coordinate is greater than B's time coordinate" implies that A happened after B in some physically reasonable sense. It doesn't - it tells us something about the coordinate system you're using. To get a physically meaningful statement, something that has observational consequences, we have to have a timelike worldline between A and B.
That makes sense. I did seem to forget that we are not talking about one thing actually happening before another but how things occur depending on our coordinate. I wish I could visualize this better. The popular BU image does not help with this.
 
  • #7
Nugatory
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I see it is painfully close to violating this rule.
It's close but not over the line. But it's time to close the thread now, I think.
 
  • #8
Buckethead
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The block universe does not imply this. There are solutions to the equations of general relativity that allow crossing one's own worldline, yes, but those exist whether or not you interpret them as implying a block universe. And "I personally do not like the implications" is not a reason to reject a theory. Or not a good reason, anyway.
I think I'm getting a better picture now. So the block universe isn't really suggesting all of time existing simultaneously, but rather its just a useful imaginary grid that allows you to picture how world lines (or slices if you like) cross each other and it's only these slices that can be considered "real".
 
  • #9
Dale
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we exist at each and every instant of time in this block. Not just as a ghostly image but as a conscious aware entity. This to me clearly cannot be the case otherwise I would be aware of every instant of time
This does not follow at all. If your “awareness” were expressed mathematically then it would be some function which varies along your worldline. The value of that function, at each event on your worldline, would depend only events in its past light cone. This is fully consistent with what we actually observe.
 
  • #10
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The thread is closed now.
 

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