Against Spacetime by Giovanni Amelino-Camelia

For better clarification my approach

I sending to you Frank Wilczek's 3 keen articles

http://ctpweb.lns.mit.edu/physics_today/phystoday/Abs_limits388.pdf

http://ctpweb.lns.mit.edu/physics_today/phystoday/Abs_limits393.pdf

http://ctpweb.lns.mit.edu/physics_today/phystoday/Abs_limits400.pdf

All the best

Yuri Danoyan

Giovanni,

{link:http://fqxi.org/community/forum/topic/1304]The problem as I see it[/link], is that we perceive time as a sequence from past to future and physics re-enforces this by treating it as a measurement issue, ie. clocks, detectors, days, etc, but the physical reality is the changing configurations turn future into past. It is not the earth traveling a narrative dimension from yesterday to tomorrow, but tomorrow becoming yesterday because the earth rotates. In this way, time is an effect of action. Like temperature it emerges from that basic thermodynamic activity. Clock rates vary, as levels of activity vary. More activity, faster clock rate. If time were a dimension from past to future, one would think a faster clock rate would travel into the future more quickly, but the opposite is true. As it ages/burns quicker, it moves into the past faster. The twin in the faster frame is dead when her twin in the slower frame returns.

Duration is not some dimension that transcends the present, but is the state of the present between detections.

Since the lightcone of any event is incomplete prior to the event, the future is probabilistic, even if the laws determining its outcome are deterministic.

It is the collapse of probabilities which yields actualities, so the cat is not both dead and alive, because there is no external timeline moving the present from past to future, but the actual occurrence of events turning future into past.

Cause and effect is not sequence, but energy exchange. Yesterday didn't cause today, any more than one rung on a ladder causes the next. It is the sun radiating on this rotating planet that creates this sequencing called days. Time is an effect, not a cause.

Knowledge is created inductively, as future becomes past, but is used deductively, as the past is used to predict the future.

link

Giovanni,

You will get maximum rating from me. Something tells me you share Magueijo's and Smolin's conviction that "the root of all the evil is special relativity":

Joao Magueijo, Faster Than the Speed of Light, p. 250: "Lee [Smolin] and I discussed these paradoxes at great length for many months, starting in January 2001. We would meet in cafés in South Kensington or Holland Park to mull over the problem. THE ROOT OF ALL THE EVIL WAS CLEARLY SPECIAL RELATIVITY. All these paradoxes resulted from well known effects such as length contraction, time dilation, or E=mc^2, all basic predictions of special relativity. And all denied the possibility of establishing a well-defined border, common to all observers, capable of containing new quantum gravitational effects."

Pentcho Valev

Hello Giovanni,

I found your essay one of the best I've read, and you argue very well for weaknesses in the spacetime interpretation at a small scale in some areas. But you talk as if all is well with spacetime elsewhere and generally, as intuition says it should be. Of course SR is right, but a close look and you'll see that all is not well generally with the spacetime interpretation. You say:

"The redundant abstraction of a macroscopic spacetime organizing all our particle detections is unproblematic and extremely useful in the classical-mechanics regime."

In fact it is not 'unproblematic', as spacetime leads unavoidably via a rigourous proof to block time, which requires motion through time not to exist, which in turn removes cause and effect. This loss of cause and effect is somewhat problematic in the classical mechanics regime.

You also say:

"Of course, the spacetime abstraction is unrenounceably convenient for organizing and streamlining our description of observations done in the classical-mechanics regime."

That is all true, except for the word 'unrenounceably'. It is convenient, and it seems harmless. But we don't understand time, and Minkowski spacetime contains a set of assumptions about time. Because we don't understand time, we have to look at the clues about time, as I've argued in my essay. If we don't look at the clues in front of us, however unexpected, I'm not sure how we're going to reach a point where we understand time. There are also missing pieces of the puzzle, and we need to allow for their existence.

Because it leads to block time, spacetime is in contradiction with the standard view of quantum theory about whether the future currently exists. That is a deep contradiction. And there are some places where the implications of spacetime jar with our picture that deeply, and conflict directly with what we observe. So although it is convenient to use, it looks like it might be flawed.

This means it is not like your analogy with the aether, which was portrayed in your quote as a useful concept, whether or not it actually exists. You sound almost like it makes little difference whether spacetime exists - and yet if it does exist, motion through time doesn't, and if it doesn't, motion through time can. That's a big difference.

So to me, you've not gone far enough in criticising spacetime, and could have strengthened your argument by pointing out other weaknesses. Of course SR is right, that has been extremely well confirmed by experiment. But the spacetime interpretation has not been confirmed, and if one gets conceptual problems with an interpretation, then one probably needs a new interpretation.

I'd appreciate any thoughts you might have on my essay. Yours and mine together show the problems with spacetime very well, though they deal with different areas.

Good luck. Best wishes,

Jonathan

Dear Giovanni Amelino-Camelia,

your introduction immediately caught my attention and compelled me to read to the end of your very fine essay. Though I disagree with the answers to those initial questions we are both saying that space-time is not required 'throughout'.I am not saying these following things to be critical of your writing but to highlight another option that is available. It is good to find someone who might be "on the same wavelength".

You wrote ".... Bob's reaction surely would have been going something like "what a stupid question! of course we all share the same time!" We now know that this question is meaningful and actually the answer is no: we established experimentally that observers in relative motion do not share the same time."

It is a fascinating conundrum. What we have IMO is two observers occupying a simultaneously existing (actualised) arrangement of the universe but observing different fabrications formed from different data. That data has been processed to give those outputs, creating the illusion of different times within the fully simultaneous external reality. So the answer isn't a simple yes or no we do or don't occupy the same time but- are we considering what exists without observation , the actualised material reality? Or the observed fabricated manifestation which is an emergent output of data processing?

You then wrote "sometimes the question we are not asking is about the meaningfulness of a notion we are taking for granted: particularly in the second half of the 19th century we were very busy attempting to establish the properties of the ether, but we then figured out that there is no place in physics for any property of the ether."

However if the observed reality is an emergent fabricated output and "beneath that" there is an actualised reality that is unobserved and the source of the data, then there -is- a place for the ether, even though it can not be directly detected.

You wrote: "To me it is irresistibly intriguing to speculate that our insistence on the availability of the spacetime abstraction might at this point be limiting our opportunities for discovery. And I am contemplating a meaningful question: it is for experiments to decide whether or not the reliability of our spacetime inferences is truly universal." I agree. If space-time is an emergent fabrication it overcomes many long standing problems. There is a diagram of an explanatory framework set out in my essay and also as a high resolution diagram in my essay thread.

You wrote:" And I argue that, as we try to get ready for going even beyond quantum mechanics, in the context of quantum-gravity research, we must contemplate even more virulent departures from the "spacetime paradigm."" Virulent may not be the best term. I regard it as the cure, the best medicine rather than a disease within theoretical physics.

Very well written, relevant, accessible thought provoking. Good luck in the competition.

Dear Giovanni,

First I must agree with you about reconsidering space-time. i think of Space-time as a very convenient lie. We build this lie with the relationships between individual particles and then fall in love with the mathematical beauty of the field and call the field real.

And space-time is very, very convenient field, it is almost as if it were genetic. Breaking away is going to be difficult, many worthwhile things are.

You may be interested in my essay in that it joins quantum mechanics and special relativity via boundary conditions. Some earlier posts indicated you had an interest in this. http://www.fqxi.org/community/forum/topic/1403

Thanks for your though provoking essay.

Don L

Jonathan,

You wrote: "Of course SR is right... (...) If we don't look at the clues in front of us, however unexpected, I'm not sure how we're going to reach a point where we understand time. There are also missing pieces of the puzzle, and we need to allow for their existence. Because it leads to block time, spacetime is in contradiction with the standard view of quantum theory about whether the future currently exists. That is a deep contradiction. And there are some places where the implications of spacetime jar with our picture that deeply, and conflict directly with what we observe. So although it is convenient to use, it looks like it might be flawed. (...) Of course SR is right..."

If spacetime is flawed, SR cannot be right. Logic forbids a situation in which the premises (Einstein's 1905 postulates) are true and the consequence (Minkowski spacetime) flawed. So let us "look at the clues in front of us, however unexpected", Jonathan.

Pentcho Valev

See my discussion with George Ellis

http://fqxi.org/community/forum/topic/1337#addPost

Pentcho, briefly,

you and I have already discussed this question at length on my page, and I have shown you to be wrong, in a way that even you eventually didn't argue back about. The reason we call it "the spacetime interpretation" is because it's an interpretation. It's untested - unlike SR, which is extremely well confirmed by experiment. People often imply that spacetime is an unavoidable consequence of SR, but no-one will actually say that it is, because it isn't.

Jonathan

Giovanni wrote:

"In quantum-gravity research there is a long-standing effort

of understanding how spacetime should be described when both

Planck's constant ~ and Newton's constant GN are nonnegligible.

We cannot claim much success addressing this issue."

Giovanni,

what mean "nonnegligible"?

Give me please more detail..

See please my essay http://fqxi.org/community/forum/topic/1413

My opinion:Planck constant is major constant of Nature.

Dear Giovanni

I agree a lot of thing with you. I agree that space-time is emergent.

I wrote my own appendix to explanation of emergence of space-time.

Mass can only run inside of elementary particles, and they are rest. Thus, in principle time does not run in empty space. Thus empty space-time does not exist, or if all matter was removed from our universe, space-time would disappear. (If relativistic mass is used in derivation of special relativity, this is still clearer.)

Do you maybe read Markopoulou? Where your theory is distinct from her?

It is interesting your viewpoint about unclear definition of run of clocks. Do you have any reference of this viewpoint, which can be found also on Internet. I am interested in more precisely described mechanism of those differences? Otherwise this seems unlikely to me, because time is the essence of mechanisms of special and general relativity ...

I am not sure also about your generalization of uncertainty principle on time and energy. I wrote about this in my essay where I suggest a different approach.

Thus I suggest my model but we agree that space-time is emergent. I suggest also that space-time is emergent, do you agree to this?

Best regards Janko Kokosar

Hi Giovanni,

I just want to say how much I enjoyed reading your essay. I've been fascinated by your notion of relative locality ever since I wrote about it for New Scientist last year, and it's great to now read about its deep implications in your paper here. Between your group's work and others' work on holography, it's hard to imagine that spacetime can survive as an observer-independent feature of the world.

That is similarly the theme of my essay here. If you have a spare moment to look at it, I'd be extremely interested to hear your thoughts. My argument, in brief, is that given the relativity of the location of information in spacetime, and given the fact that there seems to be no way to patch together different obsevers' spacetimes into a single spacetime without violating the laws of physics, we may have to give up the assumption that there exists a single universe containing multiple observers.

In any case, thanks for your wonderful essay and I look forward to following your work in the future!

All best,

Amanda

correction of the last sentence:

I suggest also that interior of black hole does not exist, do you agree to this?

Dear Giovanni,

This is a very well-written piece, in the tradition of "against" in the philosophy of physics (with Paul Feyerabend's "Against Method" and John Bell's "Against measurement").

I also feel that some of the points you make are not singular and might reflect the views of many other physicists as well. I would enjoy to hear more about your thoughts about the problem of time of tunneling. I agree that it supports the view that time in spacetime is not an absolute quantity but it is instead detector-dependent, but then what's next? Can one construct a theory based on this observation? I realy am looking forward for Ref. [2], for which the current essay is a nice teaser :-).

Best of luck with the contest.

Hi Giovanni,

In my theory everything is emergent all from a mathematical structure that describes random numbers and imperative relations between them. Interpreting the random numbers as line lengths, the relations between these lines generate all of the laws of physics. You get a beautiful unified picture of space (its points are the crossing of the lines-dynamic-), time(change of state-does not actually exist-), mass, charge, and energy.The theory is called "Quantum Statistical Automata".

It is a kind of an automata conjectured by Wolfram and Conway, but mine derived from a more fundamental idea of why reality had to come about. Of course Dr Tegmark is also a believer in the mathematical universe. I did not know any of these great people back then, but I came to believe that reality is nothing but a mathematical structure and went directly to the simplest system to implement such program. I hit on the right system in no time due to a combination of a flash of brilliance (which we all experience), my engineering/problem solving background and extraordinary luck.

From the following results it can be seen that the system shows how ordinary physics results arise plus some results that standard physics can only dream of. But the most important conclusion is that the system points to the REAL final theory. All is needed is some smart people to take it seriously, or wait for me to finish it up in due time. Of course the former will be much quicker than the later.

Fundamental Theory of Reality,"Reality is nothing but a mathematical structure, literally".

1. How I arrived at the idea.

2. Basic results that shows how QM arises, written in BASIC program.

3. Description of two particles interacting and explaining the program in C++.

4. Showing the results for Bohr atom hydrogen 1s simulation.

5. 1/r law and the running phase

6. The amazing formulas deduced from the system.

7. How spin arises from 2D simulation.

8. The appearance of the mass of the electron through simulation.

9. How gravity arises.(basic simulations not shown yet)

There are many other results not shown.Attachment #1: 4_newqsa.pdf