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Status of the block universe in the field of physics

  1. Oct 14, 2012 #1
    Hi. I did a quick search for threads on the block universe and came across one about the implications of the block universe. That was closed though because it was too philosophical. I don't really want to know about the implications of the block universe, I'm just wondering how physicsts generally see it.

    On the one hand, in the mainstream it seems as though the block universe is painted as a logical necessity of relativity. The impression that is given is that the physical representation of the mathematics of Minkowski spacetime is the block universe. On the other hand though, I've heard some people dismiss it as just a philosophical concept with no testable predictions.


    Hopefully that is an OK question for here. Please let me know if it isn't.

    Thanks.
     
  2. jcsd
  3. Oct 14, 2012 #2
    Hi levytate,

    This topic has been discussed quite a bit here. Most forum members commenting here seem to view the block universe as consistent with relativity but feel it cannot be proven to be the correct interpretation of special relativity. One of the reasons given quite often is that the Lorentz ether theory provides a differing view and that there is no way to show which view is superior to the other--LET or Block Universe. However, one argument going for the block universe is that it is consistent with a non-local quantum theory and the LET is definitely not non-local.

    Also, some claim that LET is inferior because it is a collection of special theories, each one accounting for a different aspect of relativity, whereas Einstein's theory is fundamental--it provides a foundation for physics. One of our forum members, Vandam, staunchly affirms the block universe.

    There are notable physicists who have embraced the block universe, such as Hermann Weyl and Kurt Godel (two of Einstein's close colleagues). A letter from Einstein to the wife of Besso (another close friend and colleage of Einstein's) after Besso's death is often cited as proof that Einstein also affirmed the block universe concept. Paul Davies is one of the prominent contemporary physicists who writes about the block universe (Scientific American and other publications as well as popularization physics books).

    I think it is fair to say that most practicing physicists do not talk much about the block universe--or foundational physics for that matter. Perhaps most members of this forum do not care too much for the topic.
     
  4. Oct 14, 2012 #3

    bcrowell

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    Asking for the status of the block universe in the field of physics is like asking for the status of socialism or abstract expressionism in physics. It's not physics.

    Comparing LET to the block universe doesn't make sense.

    LET was a physical theory. It made predictions (actually mostly retrodictions) about the results of experiments, essentially the same predictions as SR (although I doubt that it was sufficiently complete, consistent, and well developed to do all the things we do with SR today).

    The block universe isn't a physical theory. It doesn't make any predictions about the results of experiments.
     
  5. Oct 14, 2012 #4
    The two replies seem to be pretty representative of the state of affairs; on the one hand there seems to be some who advocate the block universe while on the other, there are those who dismiss it as just a philosophical concept.

    The impression that is created in the mainstream is that the block universe is a necessity of relativity. Is that an opinion that is shared in the mainstream of the physics community? Because the two can be quite different things.
    EDIT: It might be better to clarify that question; would the majority of physicists dismiss the block universe as just a concept, or would a large percentage see it as a logical necessity?
    Actually, would it be possible to add a poll to this thread?



    I can see bcrowell's point that the block universe don't make any predictions about the results of experiments, but some people seem to believe that the results of experiments lead to the conclusion of the block universe. Is there an alternative to the block universe that can explain the results of relativity experiments?
     
    Last edited: Oct 14, 2012
  6. Oct 14, 2012 #5

    PeterDonis

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    Saying that the block universe can explain the results of experiments is *not* equivalent to saying that the results of experiments lead to the conclusion of the block universe. The latter is a much stronger claim.

    Also, strictly speaking, as bcrowell said, the block universe does not make any predictions; it just overlays a particular interpretation on the predictions that special relativity makes. "Special relativity" here means the mathematical machinery that actually makes the predictions, combined with the operational meaning of the mathematical machinery, which is how its predictions can be compared with experimental results.

    You can use all that mathematical machinery and compare it with experiments without taking *any* position on what the proper interpretation of it is. The interpretation is something extra, over and above the theory (the mathematical machinery and its operational meaning) itself. Some people (myself included) distrust *all* interpretations, for reasons which are probably too long to fit in the margin of this post. :wink:
     
  7. Oct 14, 2012 #6

    PeterDonis

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    I don't think you can add a poll to a thread that's already started, but you should be able to open a new poll thread and link to it from this one. It would be interesting to see the results.
     
  8. Oct 15, 2012 #7
    Thanks Peter, you make some good points, all of which I would agree with. The first point about the difference in meaning between the two statements is a good one. It does seem though, that it is the latter of the two statements which seems to be put put out into the mainstream and what some people would seem to maintain. What I'm wondering is, is that representative of the mainstream thinking within the field of physics i.e. do most physicists see the block universe as the logical conclusion of relativity, or are there more physicists who dismiss it as a philosophical concept with no testable predictions, or what, very roughly speaking, is the ratio of one to the other?


    The point about overlaying the interpretation is an interesting one, and again, one I would agree with. I take your point about distrusting interpretations but I'm just wondering if you think there must be one correct interpretation of the mathematical machinery? I don't want to get into a philosophical discussion about what those might be, and by the sounds of it you would be keen to avoid one too. I would be interested to know if you think that there must be one correct interpretation, even if it currently isn't known, or is even unknowable. Would you say that the mathematics must represent some kind of physical structure of the universe? Or, perhaps, worded slightly differently, do you think that the mathematics actually do represent some underlying physical structure of the universe?


    I'm hoping those questions are close enough to yes or no questions, that they don't lead to a philosophical discussion, but I know any conversation which includes a reference to the block universe lends itself too easily to a philosophical discussion.

    If people think it would be better to start a thread in the philosophy section I would do that; I'm just wary that those who dismiss it as a philosophical concept would not be inclined to contribute there, so an integral part of the target audience could be lost.
     
  9. Oct 15, 2012 #8
    :bugeye: Do you have a reference for that? From Tim Maudlin's book "quantum non-locality and relativity" I understood just the contrary: "non-local" in the sense of Bell's theorem implies in the usual interpretation such as by Einstein, "spooky (instantaneous) action-at-a-distance". How do you manage to match that with the block universe interpretation of SR?
     
  10. Oct 15, 2012 #9

    Vanadium 50

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    Since this has been asked before, including by the OP under a different identity, this thread is closed.
     
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