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PF’s policy on Lorentz Ether Theory and Block Universe

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What is the PF’s policy on Lorentz Ether Theory and Block Universe?

Debates about the superiority or “truth” of modern Lorentz Ether Theory (LET) and the Block Universe (BU) concept are outside the scope of PF because:

  • There is little or no debate among professional physicists about these issues (as opposed to e.g. interpretations of quantum mechanics)
  • Positions on these issues are based on personal philosophical preferences and cannot be addressed (even in principle) by experiment.

The core of a scientific theory is a mathematical model which can be used to predict the outcome of experiments, i.e. in addition to the model there is a mapping between elements of the model and outcomes of experiments. This mapping is sometimes called the “minimal interpretation”. Scientifically, theories are judged on how complicated their mathematical models are and on how well they predict the outcomes of experiments, with the best models being both simple and applying to a wide variety of phenomena.

There is often a desire by the philosophical community to add more structure to a scientific theory than what is represented by the “mathematical model and minimal interpretation” described above. These structures are also generically called “interpretations”, and are most prolific in the field of quantum mechanics. Interpretations typically include some postulates which can be used to justify the mathematical model, as well as some statements about which items in the derived model are “real” and which are measurement artifacts or limitations on our knowledge.

Often a single theory is compatible with many different philosophical interpretations. There is no possible way to resolve a dispute between different philosophical interpretations through appeal to experiment because all of them make the same predictions for all experiments. The choice between philosophical interpretations is therefore entirely a matter of personal philosophical preference.

For special relativity (SR), the mathematical model is the Minkowski space, a four-dimensional pseudo-Euclidean affine manifold. The symmetry group determining this structure is the proper orthochronous Poincaré (or inhomogeneous Lorentz) group which includes the Lorentz transform.

There are two primary philosophical interpretations: the Block Universe (BU) and Lorentz Aether Theory (LET). The BU considers the universe to exist as a single fixed 4D geometric structure which is not dynamically evolving over time since time is one of the dimensions of the structure. The LET considers the universe to be a 3D world evolving over time and with a single undetectable “true” rest frame.

Both BU and LET use the Lorentz transform, etc., to make all of their experimental predictions, and therefore they are scientifically indistinguishable, making the same experimental predictions in all cases. Because of this experimental equivalence, there is little if any serious ongoing debate between the two in professional physics circles (although the philosophy literature does have ongoing debate). Professional physicists are generally content with the minimal interpretation and uninterested in philosophical interpretations.

Because there is little debate among modern scientists on this topic, and because such debates cannot be settled by appeal to experiment, and because such debates tend to degenerate into acrimonious and repetitive shouting matches, and because discussions of LET tend to attract crackpots, it is the policy of the PF Mentors who moderate the relativity forum that threads attempting to argue the superiority or veracity of either BU or LET will be closed with reference to this FAQ.

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  1. stevendaryl
    stevendaryl says:

    ”Often a single theory is compatible with many different philosophical interpretations. There is no possible way to resolve a dispute between different philosophical interpretations through appeal to experiment because all of them make the same predictions for all experiments. The choice between philosophical interpretations is therefore entirely a matter of personal philosophical preference.”
    In that case, philosophical interpretations are unnecessary, superfluous, irrelevant.

    I think that conclusion is a little bit of an exaggeration. A theory (in the operational sense of a mathematical way of generating testable predictions from observable initial conditions) might have multiple interpretations that are indistinguishable from within that theory. However, every theory that we have is tentative and incomplete–we expect that one day, our current theories will be replaced by new theories. The expectation, of course, is that new theories will have older theories as limiting cases, in the way that Newtonian physics can be seen as a kind of limit of special relativity, approximately valid in the case where all objects are traveling at nonrelativistic speeds. Even though interpretations might be irrelevant to a current theory, different interpretations of a theory can suggest different ways to extend that theory. To get back to Lorentz aether theory: it’s indistinguishable from SR. However, one could imagine extending LET to a new theory LET’, that is inconsistent with SR, but would still reproduce the predictions of SR in limiting cases.

    I’m not actually very hopeful that such a thing will happen in the case of LET, but I do believe that it is doing a disservice to physicists to say absolutely that they should never think about interpretations, because thinking about them could very well be the way to develop future theories.

  2. stevendaryl
    stevendaryl says:

    I’m not actually very hopeful that such a thing will happen in the case of LET, but I do believe that it is doing a disservice to physicists to say absolutely that they should never think about interpretations, because thinking about them could very well be the way to develop future theories.

    On the other hand, the charter for Physics Forums declares that it is for discussing existing theories, rather than developing new ones, so maybe my argument is not so relevant here.

  3. Dale
    Dale says:

    it will be helpful if some links to the wealth of available information in the PF archives is added at the bottom of that post.

    That is a good idea. Most of those threads end in a closure and/or a ban. If you remember one that didn’t end like that then it might be a good one to point to.

  4. Dale
    Dale says:

    Certainly much less than interpretations of QM, but how much exactly? Let us see
    [URL]http://lanl.arxiv.org/find/gr-qc/1/ti:+aether/0/1/0/all/0/1[/URL] (aether = 78)

    Note that the vast majority of those never made it through peer review in a reputable journal.

  5. atyy
    atyy says:

    However, every theory that we have is tentative and incomplete–we expect that one day, our current theories will be replaced by new theories.

    That is an interpretation! :smile:

    Of course, it’s the correct one. o0)

  6. atyy
    atyy says:

    Note that the vast majority of those never made it through peer review in a reputable journal.

    Hmmm, randomly clicking on them, it seems many did. Did you count?

    Edit: Also some like [URL]http://lanl.arxiv.org/abs/0801.0516[/URL] which don’t have a journal listed have been published in peer-reviewed journals [URL]http://link.springer.com/article/10.1007%2Fs10714-008-0648-y[/URL].

  7. atyy
    atyy says:

    Of the first ten I saw only two that even made it out of arXiv somewhere.

    If you took the first ten most recent, they would have had less time to have been peer-reviewed. Also, some of them are almost certainly correct despite not being peer-reviewed, eg. [URL]http://lanl.arxiv.org/abs/1404.7689[/URL] is not peer-reviewed, but is commented on in a way by [URL]http://lanl.arxiv.org/abs/1405.6351[/URL] that makes me think it is probably correct, because of Ted Jacobson’s general reputation.

    But let me count.

  8. Dale
    Dale says:

    Even if all of the remaining ones went to peer reviewed journals, that would only be a total of 70 since arXiv started. In a field that publishes as much as theoretical physics does, that certainly qualifies as “little or no debate”. It is a small sideshow at best.

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