Dear Vesselin

The topic you deal with is certainly interesting, although I see it somehow disconnected from the main topic of the contest (at least in its present version). Anyway, nice and well argued!

Good luck in the contest!

Israel

Dear Vesselin,

I'm confused! What means 'real' to a mathematician? Is space-time reality (like an apple), a model of reality, an idea not contradicting certain observations or an object in mathematicians' heaven? And more important, did space-time exist prior to Einstein/Minkowsk and if yes, in which way?

puzzled,

Heinz

Dear Yehonatan,

Thanks a lot for all this information. I have already created a folder FQXi 2020 on my computer and, like all colleagues here, will have a lot to read and think!

I am glad you are also interested in the self-force. Here is an item from the list of new results in my book Relativity and the Nature of Spacetime:

"The proper description of electromagnetic phenomena in non-inertial reference frames in terms of the anisotropic velocity of light leads to the definition of another overlooked quantity - an anisotropic volume element - which simultaneously solves two problems - it accounts for the factor of 1/2 in Fermi's potential for a charge in a gravitational field and the 4/3 factor in the self-force acting on a non-inertial charge."

Regarding your results I will definitely have a close look.

Best wishes and good luck,

Vesselin

Dear Vesselin,

Thank you for your response and further illustration of Minkowski spacetime. You state in The Ultimate Judge "all three relativistic effects have been repeatedly confirmed by experiment." I believe to be more accurate, you should say "all three relativistic effects have been repeatedly shown to be consistent with experiment." I would then agree 100% with you. However, consistency between experimental results and the interpretation of experimental results is not proof of the assumptions underlying the interpretation.

Observer A and observer B do indeed have different inertial frameworks and perceptions of time. Furthermore, Lorentz transformations can transform one reference to another with no loss of information. This is fact. Minkowski spacetime, however, is based on the assumption that physical reality is independent of any particular inertial reference frame, i.e. that physical reality is non-contextual. Certainly, non-contextuality is consistent with relativity experiments, but again, consistency is not proof.

Non-contextuality is more difficult to reconcile with quantum experiments, yet most physicists cling to the idea of a non-contextual quantum reality. This difficulty is manifested by the lack of any accepted quantum interpretation. In my essay, I argue that a contextual interpretation is consistent with quantum and relativistic experiments, but it is more general, it is based on empirically consistent and conceptually simple assumptions, and it accommodates objective becoming. I hope you will take to time to read it.

Sincerely,

Harrison

Dear Heinz,

Regarding "What means 'real' to a mathematician?" I simply wanted to point out the fact that Minkowski saw in the unification of space and time he introduced something more than just another mathematical space. My guess is that if Minkowski had to answer your second question, he would say that his die Welt (spacetime) is a mathematical model of a real four-dimensional world (when people, including myself, say "spacetime is real" we mean precisely that).

[Instead of asking you to see my answer to another comment, I will repeat it here] Let us look again at the two figures in the attached file - they represent two ontologically sharply different entities (of different dimensions): Fig. 1 depicts the suggested by our senses three-dimensional meter stick (and a three-dimensional world), whereas Fig. 2 represents a four-dimensional entity - the stick's worldtube - (and a four-dimensional world). These figures are definitely not merely different equally good descriptions of the physical reality, because reality is either 3D or 4D. If someone rejects the accepted view and holds that the dimensionality of the world is not a fundamental feature of the world (on equal footing with its very existence), then that should be explicitly stated and arguments, based on the experimental evidence, should be provided.

Now the question is whether experiment can determine the dimensionality of the meter stick (and therefore of the world). This is precisely what the experimental verification of length contraction did. And I would like to stress it again: I think that is the strongest form of experimental verification - if the meter stick's worldtube were not a real 4D object (depicted in Fig. 2), length contraction would be impossible.

Best wishes,

VesselinAttachment #1: 1_BlockU.jpg

Dear Harrison,

I read your comments several times and, frankly, do not see on what grounds the experimental verification of length contraction should be downgraded from a "proof" to "consistent".

Let us look again at the two figures in the attached file - they represent two ontologically sharply different entities (of different dimensions): Fig. 1 depicts the suggested by our senses three-dimensional meter stick (and a three-dimensional world), whereas Fig. 2 represents a four-dimensional entity - the stick's worldtube - (and a four-dimensional world). These figures are definitely not merely different equally good descriptions of the physical reality, because reality is either 3D or 4D. If someone rejects the accepted view and holds that the dimensionality of the world is not a fundamental feature of the world (on equal footing with its very existence), then that should be explicitly stated and arguments, based on the experimental evidence, should be provided.

Now the question is whether experiment can determine the dimensionality of the meter stick (and therefore of the world). This is precisely what the experimental verification of length contraction did. And I would like to stress it again: I think that is the strongest form of experimental verification - if the meter stick's worldtube were not a real 4D object (depicted in Fig. 2), length contraction would be impossible.

In your comment you talk more about describing physical reality, whereas Minkowski asked the fundamental question: What is the dimensionality of the physical reality? How to describe it is a separate question.

Of course, I will read your essay - it is already in my FQXi 2020 folder.

Best wishes,

Vesselin

7 days later

Dear Vesselin,

I very much agree with your observation that a conversation about the nature of spacetime is long overdue. I tackle similar territory in my own essay from the perspective of quantum logic, a perspective mind you, when I first heard about it I dismissed as not being logic. I invite you to take a look. I should say though I take a diametrically opposite view to yours and argue for an objective becoming.

I recently came across a paper by a historian of physics who argued that Einstein did not view his theory as a geometrisation but as the unification of gravity and inertia. I found that quite thought provoking.

I wish you all the best with the contest.

Warm wishes

Mozibur Ullah

4 days later

Thank you for your patience. It is very difficult to separate empirical facts from interpretations, based on assumptions. I have focused on quantum interpretations and have concluded that quantum reality is objectively contextual. You have prompted me to examine more closely the empirical evidence and assumptions regarding the physical reality of non-contextual 4D spacetime. Thank you.

Best,

Harrison

Thanks a lot. I read your essay several days ago but need to think a bit more in order to try to provide helpful comments.

In the meantime, you could think of submitting an article to the forthcoming Minkowski Institute Magazine, if interested (http://www.minkowskiinstitute.org/MIMagazine.html).

Best wishes,

Vesselin

Hi Vesselin,

Our previous discussion has prompted me to take a deeper dive into empirical measurements, facts, and interpretations.

The Michelson-Morley experiment demonstrated the truth of statement A: "Whatever inertial reference frame is measured from, the speed of light is the same." We can take A as empirical fact. A underlies the Lorentz transformations, which we can also accept as true. The Lorentz transformations transform the measurements of physical reality from one inertial reference to another, including measurements of time and length.

Consider the statement B: "Physical reality is non-contextual." In the context of SR, this means that physical reality is independent of the particular inertial reference from which it is measured. Without going into details, I claim that B is logically equivalent to statement C: "Physical reality is described by 4D spacetime." I further claim that (BC) => A. We have accepted A as true. The truth of A is consistent with the truth of B and C, but the truth of A neither proves nor implies the truth of B and C.

Rejecting B and C does not contradict the Michelson-Morley experiment or the Lorentz transformations. It is simply a question of whether we assume that physical reality is contextual or non-contextual. Insofar as the Lorentz transformation preserves information and given that time in SR is reversible, the contextuality of physical reality in SR is undecidable. It is simply a matter of assumption.

I do not believe this is the case for quantum mechanics, in which wavefunction collapse is empirically irreversible and information is not conserved. As described in my essay, I believe that quantum mechanics provides a strong case for the fundamental non-contextuality of physical reality. If this is true, unification of quantum mechanics and relativity would require accepting the non-contextuality of relativitistic physical reality, as well.

Best,

Harrison

    Dear Harrison,

    Thank you for taking the time to write on this.

    I found the discussions on the nature of spacetime to be almost always discouraging, especially when I ask to focus on Minkowski's argument - length contraction - since it allows a single explanation (that does not contradict the experimental evidence) and because of that it is clear cut: if that argument is refuted it amounts to rejecting the reality of spacetime (the same applies to time dilation and the twin paradox, but their analysis is a bit more complicated). Despite that every time I explicitly ask to address this argument, every time it is ignored and other arguments are put forward. Unfortunately, this happened again - I even attached a diagram of a more visualized presentation of Minkowski's argument.

    Frankly, I really do not know how to comment; at least, I hope you understand.

    Best wishes,

    Vesselin

    P.S. In physics, the physical world is regarded as independent of reference frames (used for its description; what is described does not depend on the choice of its description). This is not debated in physics. On 2-3 occasions I witnessed almost identical reaction when non-physicists try to question it - "I have no time for exercises in philosophy of language".

    13 days later

    A new era dawns.聽 Old questions become quaint and historical.聽 Is the whole community ready?聽 Or is physical reality too dangerous for our collective understanding at this time?聽

    Dear Vesselin,

    A most interesting essay, as I was not aware of the thoughts of Minkowski.

    I, however, am a presentist who believes time is illusary. I am also a staunch believer in a finite, rotating 3D universe. If you need to attach a time axis then I think I ascribe to typical time (relative, dilated time flow, wrt a defined volume of space) and atypical time (absolute, cosmological, expansion of aether master clock) both running together, to be used cautiously and not confused.

    I haven't read Rovelli's paper but he usually strikes a resonance with me, despite our numerous disagreements.

    While I struggle to work out and define objective reality, I met a guy in the park today who argues strongly that there is only subjective reality! (I must read 'Zen and the art of motorcycle maintenance' again !)

    Regarding Minkowski again, I do not personally buy into length contraction but rather think there is only time flow dilation to deal with (Inertia of energy density)

    best wishes,

    Marts Liena

      Dear Marts,

      Thank you for your comments. I guess you may also wonder what should be done when there are so many people with so many different views of the same world. For this reason, one of the elements of the research strategy of the Minkowski Institute (Montreal) is to provide justification for excluding research directions. I am well-aware that some people will be outraged by such undemocratic intervention. The first class on my course on foundations and philosophy of spacetime was always devoted to the explanation of some basis principles, e.g., that there is no democracy in science (and I was telling the students that everyone is, of course, entitled to their views, but we should constantly keep in mind that Nature does not care about our personal opinions). I suspect that "political correctness" in science is hampering the advancement of fundamental physics. Personally, I will be genuinely glad if I am shown (with arguments based on the experimental evidence) that a project I am working on or a view I hold are wrong. I am convinced I am not alone since, ultimately, we want to understand the world, not to demonstrate that we are right.

      Best wishes,

      Vesselin

      P.S. With regard to your last paragraph, I hope you are aware that both time dilation and length contractions are specific manifestations of relativity of simultaneity.

      Dear Vesselin,

      An interesting essay, that I am at odds with.

      You comment: " ...the accepted view that dimensionality of the world is one of its most fundamental features.." Dimensionality, per se, is a human construct that can be most confusing. Your essay discusses 3D universe vs 4D spacetime from the viewpoint of Minkowski. I wonder what we are really discussing when we talk about dimensions. String theorists accept 6 space dimensions, with 5 other dimensions in some versions. Aside from mathematical representations, how can we have 3 extra spatial dimensions? (curled up or not). I regard 4D spacetime as a mathematical construct only as I believe time is illusory. I accept 3 space dimensions because they represent my degrees of freedom of movement. But I do not ever accept 1 or 2 spatial dimensions (except mathematically) as everything 'real' in my physical ontology must have volume.

      I did not understand what you meant by 'becoming' until I read the Rovelli reference, which explained it nicely. I am a presentist but I do not go along with Rovelli's arguments against presentism. I do not accept his view of simultaneity, nor that of Hillary Putnam. As I have a working, non-self referential, definition for time, I regard the 'present' or the 'Now' for each observer to be strictly local. That means planes of simultaneity cannot be extended globally, as in Rovelli's fig.2. I also counter his Big Bang argument by allowing the 'BB' to occur over an extended 3D space (like a phase change in the primordial energy).

      In my essay I discuss presentism of another kind, which I have called Relative Verdandism (RV).

      As previously mentioned SR eliminates absolute simultaneity for all observers so it eliminates a universal observer present across all space. General Relativity (GR), as defined by Einstein, is compatible with relative verdandism, as GR considers how both energy and momentum (mass times velocity) warp space-time. RV can be seen as a universe of three-dimensional space modulated by the movement (change) of the energy contained within. Note that General Relativity and Relative Verdandism are theories that do not require 'observers', unlike Special Relativity which requires observers with clocks and rulers. Cross-temporal relations do not pose an issue as I have allowed the physical (electric, magnetic and gravitational) force laws of to act between disparate energy forms in space so that causal relations still hold.

      Kind Regards

      Lockie Cresswell

      Dear Vesselin,

      There is already "exclusion of research directions"; such is inherent in entrenched establishments. The members of such establishments are human, hence essentially tribal, and "our tribe is always right."

      I quote McEachern in my essay:

      "...Planck observed a century ago, the problem is, theoretical physicists are not part-icularly adept at identifying that some things even are assumptions; with the result that 'self-evidently true' facts lead to long periods of stagnation, until these "facts" are eventually shown to be just idealistic false assumptions."

      Einstein built his false assumptions into his definition of 'inertial reference frame' and Minkowski built his false assumptions into his 4D ontology.

      Special relativity is not the only area of physics that has false assumptions in its fundamentals, but all such areas have books, papers, lectures, professorships, and other investments that oppose any serious focus on such fundamental false assumptions. 'Political correctness' has nothing to do with it. It's the nature of the hierarchical establishment, period.

      The lack of real progress in 40 years is near proof of this state of physics, and many in these contests believe the dam may be starting to break, but that's probably optimistic.

      Best wishes,

      Edwin Eugene Klingman

      Dear Dr. Petkov, dear Dr. Crecraft,

      I have followed your very interesting discussion, but, it's only my first essay contest here, so I did not understand all arguments. Could you give me some comments on the following:

      - I totally agree that all experiments that Dr. Petkov shows clearly refute the 3d-space plus 1d-time world in favour of a 4d-spacetime, which remains a good world even when we add gravitation to it.

      But how do these experiments guarantee that Minkowskis 4d-spacetime is the only possible explanation of the observed phenomena? (This goes in the direction of Popper's arguments that we can only refute hypotheses, like the 3d space, but how can we guarantee, for instance, that we are not moving w.r.t. some ether, we could just be moving so slowly that our detectors cannot measure it or we could think of some other effect compensating that motion. What I mean: there could be degeneracies)

      - I agree to Dr. Crecraft, stating that observations are the important keys to probe our universe. I also believe that our theories and hypothesis describe ontologies and don't end in solipsism. Yet, are observations true facts, as you write in a comment above? How about the argument that every observation is, to some degree, again dependent on some potentially unproven assumptions? (This goes in the direction of quantum mechanics that knowledge becomes observer-dependent, here dependent on the observer's assumptions and interpretations of the measurement.)

      I would highly appreciate your ideas on these questions.

      Best wishes to both of you for the essay contest!

      Sincerely,

      Jenny Wagner

      Dear Edwin,

      I see... If by chance you decide to entertain the possibility that both Einstein and Minkowski are correct (which is an experimental fact for all who studied both their works and the overwhelming experimental evidence that confirmed their results), you could look at the visualized version of Minkowski's explanation of length contraction (see the text quoted in my reply to Harrison Crecraft and the figure given there) and I will be glad to answer all your questions.

      I am truly amazed that you quoted Planck - the man who first realized the depth of Einstein's special relativity and was instrumental in its fast acceptance. I guess you did not like what Planck sadly wrote (in his "Scientific Autobiography" and in his book "The Philosophy of Physics") about the acceptance of new revolutionary theories:

      "This experience gave me also an opportunity to learn a fact - a remarkable one, in my opinion: A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it."

      Best wishes and, again, I am willing to reply to your questions,

      Vesselin