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  • Post #21

The author postulates layers of space time. How the layers can be distinguished from one another. Is there a non-homogeneity in space or how one can separately treat these layers. i often wonder about distortion in space and time that may be shortterm or longer term. May be such distortions are not taking place in the universe now.But these may have taken place closer to the birth of the Universe. Thus it will be very significant to do such cosmological experiments for the early universe. he secrets of unknown physics to me are tied up with what happened in the universe closer to its birth. The Particle Physics appraoch for the same kind of experiments is fraught with huge cost and difficulty in execution ( LHC accelerators).

Smothness between classical and quantum physics also bothers me. The universe evolution is a wonderful example of high logic intelligence. The processes we study appear random in nature as these can not be studied as individual events. But wherein we consider the logic intelligent design. That can not be random in nature and completely probabilistic. Thus truth may be considered to possess an illusion associated with it. We need to sharpen our minds to isolate the 'tricks' nature is playing with us, a challenge for 'smart ' human beings who profess to do high-brow Physics using intelligent Mathematics.

Dear Narendra Nath,

thank you for your thoughtfull comments on my article. I will make a few remarks in return, citing appropriate parts from your statements:

"The author postulates layers of space time." -- This I do not understand. In my article, as well as in others' recent work on causal sets, and in any microscopic theory of spacetime, there is the *reductionist* assumption that there is substructure to what we perceive at the distance etc. scales set by us being as we are, say biologically. Physics is, among other topics, about relating phenomena at different scales in a *comprehensible* way.

" ... taken place closer to the birth of the Universe." -- I presume, most people agree with this. The common folklore being that the *highly energetic* circumstances at the Big Bang must relate to what we try to explore in high energy particle physics, for example. Therefore, accelerator physics is an important avenue to continue, new and *cheaper* technologies for this are continuously beeing developped. -- Your scepticism on costs and difficulties is well taken. However, this should be seen in perspective and relative to the horrendous waste of resources our society produces daily!

Work at big accelerators has been among the few working examples of peacefull and international and fruitfull and , last not least, highly educational collaborations among humans.

"Smothness between classical and quantum physics also bothers me. The universe evolution is a wonderful example of high logic intelligence. ... " -- From here on, you seem to address metaphysical convictions, which I do not fully share. In particular, the question of "intelligent design", or not, seems very ill-posed to me and originating from a need for metaphysical orientation. Which is definitely fine with me. However, it is also clearly *beyond physics*, understanding the latter as beeing set on its historical path by the rational, questioning-and-experimenting methodology advanced by Galileo Galilei.

(If *we* were able to decide on the question of "intelligent design" of the Universe, it could at best be as intelligent as ourselves ... , and there are, without any doubt, many obvious limitations to that.)

Thank you again, with my best regards,

Hans-Thomas Elze

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  • Post #23

Greetings Hans-Thomas. Balance and completeness go hand-in-hand in theory and in life. This can include a sort of "neutrality" involving the unification/merger of opposites. You touch on this to some extent.

Do you agree that the fundamental union of gravity and electromagnetism/light necessarily/ideally involves balancing scale by making gravity repulsive and attractive as electromagentic energy/light? Given the pervasive effects of electromagnetism/light, closely consider: 1)No time at light speed. 2)One cannot catch up to a photon. 3)No feeling of gravity in outer space. 4)Our relative/natural immobilization in outer space (and in reference to photons). 5) Now look at the extremes of size/visibility/energy/brightness involving electromagnetism/light (the Sun and photons).

Our essays discuss many similar and very important issues. My essay is the fourth one listed.

ADDENDUM:

Dear Narendra Nath,

in order to avoid misunderstandings, let me emphasize that I am not a sole, if not lost defender of *accelerator physics* -- this was just meant as an immediate reply to your concerns. Instead, I believe strongly that research into the foundations of quantum mechanics, which is still at the level of *table top experiments*, as compared to (astro-)particle physics, promises to be one of the most fruitfull, near-future *gardens of Eden* to explore. Crises are imminent, by experience, whenever one (field of research) dominates the others ...

Best wishes, Hans-Thomas Elze

Dear Frank Martin DiMeglio,

thank you for your comments! I am not sure, I fully get what you want to express by points 1) - 5) of your message. Concerning the philosophical remark on the merger or, let us say, interplay of opposites, I find this as teasing the mind as you. The problem is to make such ideas concrete, i.e., to locate them WITHIN physics.

The problem of antigravity that you mention has come up time and again in research, without a definite outcome, as far as I know. An interesting twist on this story are works by Kaplan and Sundrum, Hossenfelder, myself, and others, which discuss a related energy-parity symmetry in various contexts (papers onine at the arXiv). Most attractive feature of this would be a zeroth order cancellation of the particle physics contributions to the cosmological constant.

Your mentioning of dreams, with a loose bridge to physics notions or experiences, I find interesting -- but beyond physics, at this time. Are you aware of the extensive correspondence between W Pauli and C G Jung on these matters; it is inspiring to read but difficult to get something *tangible* out of it ...

Thank you again, and best regards,

Hans-Thomas Elze

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  • Post #26

Hello Hans-Thomas. You are very welcome, and thank you for your reply.

Antigravity fundamentally relates to the balancing and unification of gravity and electromagnetism/light (in dreams, that is): 1)Our relative immobility therein 2)Being in a larger and smaller space at once -- i.e., gravitational expansion/contraction 3)Dreams of falling and flying 4)The varaible distance/size of space in dreams.

A key component of unifying gravity and electromagnetism/light is the demonstration/understanding of scale as balanced by representing space as BOTH invisible and visible. Points 1 through 5 relate to unifying/balancing gravitational space and/as electromagnetic energy/light. I have demonstrated a firm bridge to physics with all of this (including what is in my last post) in dreams. I have located/demonstrated the interplay of opposites in dreams in conjunction with the reconfiguration of the sensory experience in dreams. This interplay of opposites in dreams is the reason that dream experience is different from waking experience, by the way. Sensory experience is/includes physics. Balancing scale: Note that objects are closer together on Earth and more distant in outer space (in relation to the Sun). See the connection with repulsive/attractive, scale, and gravity/electromagnetism?

Do you agree that it is plain and simple common sense that the known mathematical unification of Einstein's theory of gravity (general relativity) with Maxwell's theory of light (electromagnetism) that is achieved by the addition of a fourth dimension of space to Einstein's theory must be plainly and significantly obvious in our direct experience?

This discussion is more about your essay. I respect/realize that. Do you have any questions of me regarding the points in your essay, or do you wish to further discuss some of the more difficult points/topics in your essay?

You mentioned my awareness of extensive correspondence between W Pauli and C G Jung on related matters/dreams. I will take a look at this. Thank you.

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  • Post #27

In addition to the questions/points in my last post to you, do you agree that the fundamental union of gravity and electromagnetism/light necessarily or ideally involves balancing scale by making gravity repulsive and attractive as electromagentic energy/light? Are you still considering this question (from my first post to you)?

This is a very relevant and important question. Thanks. Frank

Dear Frank Martin DiMeglio,

since it is fun to discuss and I have a free day ... let me just add few more remarks / questions.

I do not see why unifying electromagnetism and gravity necessarily says something about the need to have antigravity. The only model of this kind, which seems to have survived as a platform for discussion for a number of decades is the Kaluza-Klein idea that gravity and electromagnetism (and possibly other gauge fields) could be unified in a 5-dimensional geometry (with one compactified dimension): there is no trace of antigravity in this, as far as I know.

Why do you insist on gravity and electromagnetism? All currently discussed ideas depart from the unification of electromagnetic/strong/weak interactions, as achieved in the Standard model based on the gauge theory paradigm. Gravity, for many reasons, seems a separate case, which is not easily molded into this.

Furthermore, invoking dream experiences clearly takes us far outside of physics, since consciousness/subconsciousness/dreams are certainly not grasped by present theories, neither physical, chemical, nor biological, there seem to be at best a few pieces of a big puzzle ... and a lot of speculation.

All of this goes far beyond what my essay modestly tries to talk about, so I am afraid that my competence is too limited to make a valid contribution to your ideas.

With best regards,

Hans-Thomas Elze

Dear Frank Martin DiMeglio,

I am sorry that I obviously did not find the right words to communicate serious concerns with you. In any case, it was fun, and I thank you for your rating.

Best regards, Hans-Thomas Elze

Thomas

A fine essay on a very important subject.

In fact I include some of your underlying issues among the points of my essay - in a rudimentary and elementary way suitable for non-physicist general readers (at least those with a sense of humour). My conclusion is that an ultimate limit on physics is the (in)effectiveness of its formalisms (maths and logic). My other conclusion is that we need new foundations for our formalisms.

There are physical principles but no empirical content in your paper. That is not a criticism (even if Uncle Al is watching us). I see it as necessary when examining conceptual foundations. So your work, as i see it, uses a new formalism - but one using concepts derived from existing foundational ones. I think that may be the hidden limiting variable in your work.

Thomas

Addendum: I wanted to refer you to the final quote (from Gershwin) of my essay !

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  • Post #33

Dear Hans-Thomas,

I enjoyed reading your essay. I have some

questions/comments.

1. If I understand correctly, you have contributed the notion of "extensity" as

a way to implement matter within the causet framework. Previously this

framework existed only for spacetime, w.r.t the property of "causality".

2. Spacetime-matter duality follows. I liked the picture you presented in which

you criticise the notion that most people have (myself included), that

spacetime can be thought of as devoid of matter, while nobody can image matter

living outside, or independently of, being embedded within a spacetime. This is

very cute, I'd never thought about it, it shows how deeply prejudiced one can be

without even being aware of it.

3. Nature is however highly nonsymmetric w.r.t. the spacetime-matter duality. A

posteriori, this is kind of a justification for our prejudice as mentioned

above.

4. It follows that some symmetry-breaking mechanism must be present, some kind

of Higgs particle, that brings us into this nonsymmetric state.

5. Do I understand correctly, that the symmetry breaking is due to the presence

of interactions? This notion is appealing, but it raises some doubts. In the

continuum limit, many interactions (the gravitational one first and foremost)

can be mimicked by passing to an appropriate reference frame (this is the

principle of equivalence). This is, in a sense, a way of rendering interactions

"unphysical", because we can mimic them geometrically. Something similar (though

not exactly identical) happens in classical mechanics on phase space, when one

considers the Hamilton-Jacobi equation: one looks for new canonical coordinates

and momenta such that the system, however complicated in the old variables,

evolves freely in the new variables.

6. Which leads me to the point: at least in the continuum limit, interactions

will not do as a symmetry-breaking mechanism. This raises the possibility that

interactions will also not do before the continuum limit is taken. What makes

you think they will? And, in case they do serve as a Higgs mechanism, how

exactly do they do so? I think this is the crux of the matter.

I enjoy looking at things from a dual perspective, and I found the duality you

presented very interesting. I think it may be related to my old programme of

"rendering the notion of an elementary quantum relative to the observer", which

is my own, dual way of "quantising gravity", if you wish.

Just one more thought-

at least in the continuum limit, judging by the two examples given (gravitaion

and Hamilton-Jacobi), interactions are actually a statement of the duality

between spacetime and matter, rather than a statement of the symmetry breaking

thereof. Of course, in the discrete causet framework this might be otherwise.

But then one has to account for the fact that a symmetry-breaking mechanism in

the discrete picture actually becomes a manifestation of the symmetry itself in

the continuum limit. This I find somewhat bizarre, though of course not

impossible.

Jose.

Dear Tony Padden,

many thanks for your comments and putting our articles in perspective. And yes, of course, I try to make a suggestion for a little next step. - I will look at your paper over the weekend, since a piece of humour in a lot of meta-physical considerations that one encounters sounds really like a promise of wellcome "refreshment"!

Thanks again and my best regards,

Hans-Thomas Elze

Dear Jose Isidro,

thank you for your detailed and thoughtful comments / questions for my article. Let me reply, following your points:

1. Yes, to introduce "extensity" is an attempt to have a primordial trace of matter, when trying to build up a theory of spacetime-matter following the successful layout of the causal set approach. Invariably, discreteness is an ingredient from the outset.

2. Duality is a symmetry which may or may not be realized. Since there are two partial orders introduced, it is natural that they somehow influence each other: this must be the role of dynamics.

3. Yes, as I mentioned in the article, QM and GR depart from the experience that empty space or weak gravitational fields are excellent approximations under the conditions that have been accessible to us. However, the suspicion cannot be refuted that this also conditioned both theoretical constructs, which resist to be embedded in a more encompassing structure and understanding, for technical reasons that have been related in many ways to their formulation, as it is.

4. This is hard to say before various dynamical toy models have been studied, in order to get a feeling how the apparent asymmetry can arise. I have two possibilities in mind: matter, as we know it, may present a perturbation on top of a perfectly dual state, or the asymmetry is due to a sort of phase transition breaking the duality. Other possibilities are not excluded.

5. Yes, interactions will be essential. I do not think that this raises doubts, on the contrary: the two partial orders form a "pre-geometrical" picture. In the causal set program, for example, geometry is produced only in the limit of sufficiently large causal sets.

6. I am not sure that I understand your statement. --

Yes, I am aware of your work that you mention. However, I have not thought about a possible relation to what is said here. If I remember correctly, your ideas do not invoke discreteness as a fundamental feature, but discuss this as a result of "quantization"?

Your 'last thought' "... that a symmetry-breaking mechanism in the discrete picture actually becomes a manifestation of the symmetry itself in the continuum ..." is intriguing. -- Certainly, one has to account for, say, Standard Model symmetries somehow (Kaluza-Klein?), of which there seems to be no trace in the underlying discrete structure. You can find hints in the literature that people working along these lines are quite aware of the need to have symmetries "emerge" in discrete theories (R Sorkin, G 't Hooft, F Markopoulou, S Adler, O Dreyer, D Oriti, G Vitiello, B-L Hu, F Girelli, ... ).

Thank you again for giving me the occasion to expand on these matters here.

With best regards,

Hans-Thomas Elze

9 days later

Dear Hans-Thomas,

I need to admit to having a hard time understanding your 'extensity' relation. What does it mean, intuitively, when u is extended by v? My first mental explanation for this was something along the lines: "well, it's like with Russian dolls, chunks of matter are nested inside each other, so that the partial order records the successive fine-graining of matter". However, now I think that this cannot be what you mean, for two reasons: the first reason being that the elements of a causet are supposed to be the smallest entities of spacetime, its points, and therefore cannot stand for whole chunks of matter nested inside each other. The second reason being that parity reversal also reverses the extensity relation, as equation (6) and the resulting explanation seem to show.

Another explanation I pondered was that 'u is extended by v' could mean something like 'u and v belong to the same piece of matter'. But then, this relation should be an equivalence relation, and not a partial order!

Can you clear up the confusion? Sorry for being slow in understanding.

Last but not least, a minor technical point: your symmetry group doesn't contain time reversal by itself, and neither does it contain parity reversal by itself, although both are symmetries of the kinematics. Why? Wouldn't it be better to consider the full 8-element symmetry group generated by time reversal, parity reversal, and spacetime-matter duality?

best wishes, Tobias

PS: it's good to see familiar names here in the essay contest! (Växjö)

Dear Tobias Fritz,

it is good to hear from you! And thank you for pondering about my article. - Let me reply to your comments:

The Russian doll idea you mention is interesting in itself, a sort of "bootstrap" mechanism to introduce matter, perhaps? However, indeed, I have not thought about this. Instead I depart from the reasoning that matter should be present but distinct from entities related to spacetime (I mention some current ideas in the causal set literature that attach aspects of matter to the "spacetime atoms", which obscures simplicity and beauty of the picture).

Your second interpretation is closer to what I propose, namely that the only "place" naturally left empty "in between" events in the causal set approach is on the spacelike relations. They can carry matter, which is represented by the extensional relation.

There are two reasons for a partial order here: a) matter is assumed not to exist pointlike but extended; b) the order introduces a notion of direction. One could also say that matter introduces an asymmetric correlation between spacelike events.

Concerning the symmetry group, I agree with you. I introduced only the most rudimentary idea, for simplicity. In particular, when it comes to interactions, one likely has to enlarge the set by operators which interfere with the present symmetry, but could be embedded in a larger group, as you indicate.

I hope, these remarks clarify the points you make.

With my best regards,

Hans-Thomas Elze

PS: Perhaps we meet at Vaxjoe 2010 again, or at DICE2010 here in Italy!

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  • Post #38

I will have to read your paper again I think. You do seem to make the point that a duality between matter and spacetime can be obtained from a causal net structure based rather much on logic. I have been working on how spacetime is similar in ways to solid state physics, in particular with tesselations and quantum error correction codes.

Cheers LC

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  • Post #39

Dear Hans-Thomas Elze,

I apologize for not having read your essay yet because I do perhaps not agree with you in important issues. Nonetheless, I would like to ask you: What does the notion "causal set" mean with reference to the very moment?

Regards,

Eckard

Dear Lawrence B. Crowell,

thank you for your message and the hint about

possible relations to your work! - Yes, a partial

order, as in the usual causal set approach, provides

a minimal structure to incorporate causality, assuming

this is fundamental (conjectured by philosophers and

physicists alike, even if not by all).

Invoking two such orders, naturally opens a much

richer spectrum of possibilities, the duality being

a very simple but striking possibility, besides

dynamics.

Thank you again and best regards,

Hans-Thomas Elze

Dear Eckard Blumschein,

thank you for your message. It makes me curious to learn your point of view, in particular, since you mention to possibly disagree. - Do I understand your question correctly as referring to what corresponds to the notion of "now" in a causal set? If so, this can be answered: the "now", corresponding to a time slice, can be seen as the collection of last added elements in a growing causal set; in particular, these are all elements that do not precede any other element, according to the order relation.

For details and technical aspects, I recommend the works by R Sorkin and collaborators (all recent papers are available at arXiv.org, see arXiv:gr-qc/0309009 especially, which is a nice introduction and review), who introduced the modern causal set idea. My suggestion in the paper is to consider two partial orders, instead of one (the causal order) - and to explore the possibly surprising consequences.

Best regards,

Hans-Thomas Elze