Three questions regarding QG theories

[Kontilera]

Hi all!
Im gonna try to keep it short but as detailed as possible.
First of all, sorry for my lower level english, possible misunderstandings of the physics Im talking about and misusage of the forum, Im not sure if vague threads like this is allowed at all. Please feel free to just answer yes/no, Im just curious.

With that said, lets start. :)
I did read physics at a the university and was interested in physics beyond the standard model but never got far enough in order to really get a hint of it. My experience of theoretical physics aiming for unification was that the mathematics became quite sprawling. Differential geometry, clifford algebras, geometric algebra, Im sure these paths have different justifications and goals, but I didnt understand where to start. In my recent flow on youtube I got a lecture by Baez about the tenfold way, which seemed to confirm this equivalence between different descriptions. My first question is thus:

Do you agree that there today is a multitude of languages within mathematics that seem to have some potential to describe the same things in physics beyond the standard model?

My second question is following:

If yes, is there a chance that this arbitrariness of the mathematical language is a sign of a symmetry on a higher lever? Maybe on a "categorical level"? Just as the gauge symmetries doesnt correspond the any physical symmetries but rather the excess of degrees of freedom in our mathematical formulations, some physics might be extracted on a description of such a higher symmetry.

Lastly, regarding the situation of different theories for QG. It seems natural, to take interest in the anomalies of physics in order to be able weed some of them out. Could the collapse of the wavefunction be a candidate as we have two different theories (quantum and classical physics) but no "continouos correpondence" between these two? Do you think there is any hope to able to find some peculiarty, something measureable in this collapse that actually could help us understand physics beyond the standard model?

Thanks you in advance.

 

[Kontilera]

I understand that it would indeed be very presumptuous to expect any explanative answer to questions like this, but I would be happy just to know if any of these ideas actually does exist with in the field, or if Im waaay out.

 

[Vanadium 50]

Your first question is trivially true. Everything has some possibility of being part of the answer.

I cannot make sense of your second question.

The assumptions behind your third is not correct. QM encompasses all of the classical domain and more. Classsical mechanics is an approximation of QM suitable for large scales.

 

[Kontilera]

Your first question is trivially true. Everything has some possibility of being part of the answer.

I cannot make sense of your second question.

The assumptions behind your third is not correct. QM encompasses all of the classical domain and more. Classsical mechanics is an approximation of QM suitable for large scales.

Thank you.
Let me rephrase my first question and third question.

Do you agree that there today is a multitude of languages within mathematics that seem to describe the same things in physics beyond the standard model?

Is there, among physicists in the field, any kind of hope that the collapse of the wavefunction eventually could brind clues within QG ?

 

[Fra]

My second question is following:

If yes, is there a chance that this arbitrariness of the mathematical language is a sign of a symmetry on a higher lever?

I think to say no seems unjustified, so yes.

Set aside physics, different models that seem to describe totally different state spaces, can make the same predictions in some common domain. Various theory dualities such as AdS/CFT or generalizations thereof. Various "equivalent" ways may have various pros and cons when looking at the requirements required to compute or represent them, that may have some physical significance when you consider the PHYSICS of information processing. And part of QG research considers things like computational complexity and seeing black holes as "optimal scramblers" etc. The issues of information paradoxes of BH radiation etc. All these things together suggests some deep things that may lie below both quantum foundations and the nature of gravity that may be a key to unify the two. So ultimate symmetry may philosophically something like, "any computation and any representation is allowed" but not are equally efficient, so symmetry is broken. It could probably be formalized.

A less deep interpretation that is withing mathematics there are many relation between various fields of mathematics, such as stochastic process and geometry. For example the mean path of a random walker may well follow a defined geometry. There are analysis vs algebra, analytical functions can be seen instead as infinite dimensional linear spaecs etc. Which is these is used may be part from tradition, or I think which makes for more compact of efficient notation in working with theories. Or that it some may prefer to think in terms of geometries, while other may prefer to think in terms of random processes. Different abstractions may give you different hooks to gain understanding and intuition. We may have our own favourite ways.

Lastly, regarding the situation of different theories for QG. It seems natural, to take interest in the anomalies of physics in order to be able weed some of them out. Could the collapse of the wavefunction be a candidate as we have two different theories (quantum and classical physics) but no "continouos correpondence" between these two? Do you think there is any hope to able to find some peculiarty, something measureable in this collapse that actually could help us understand physics beyond the standard model?

Your specific wording, makes me think of ideas such as that or Roger Penrose. But if one interprets your question broader, such as wether the foundations of QM (the "collapse" beeing at it's heart) and the nature of gravity may be related I think it cant be ruled out either.

/Fredrik

 

[hutchphd]

we have two different theories (quantum and classical physics) but no "continouos correpondence" between these two

Please provide a reference for (or explanation of) what this means to you. There are formal attempts (path integral formulation for one) which view classical mechanics as the natural limit of quantum mechanics, so I do not understand your statement.
Continuing by badly mix metaphors: there are in fact still "far more things in heavan and earth Horatio than are dreamt" Any incomplete explanation will lead to blind men describing elephants. We are in the kingdom of the blind, and badly need a one-eyed man.

 

[Kontilera]

Please provide a reference for (or explanation of) what this means to you. There are formal attempts (path integral formulation for one) which view classical mechanics as the natural limit of quantum mechanics, so I do not understand your statement.
Continuing by badly mix metaphors: there are in fact still "far more things in heavan and earth Horatio than are dreamt" Any incomplete explanation will lead to blind men describing elephants. We are in the kingdom of the blind, and badly need a one-eyed man.

My understanding is that there is, of course, a correspondence between QM and classical physics in different aspects, calculating means or path integrals could be two of them. But it appears to me that, although the theories are (what I as a layman would call) deterministic in their own regime, the process of measurement is not. The transition from wave to particle for a single electron in a dubble slit experiment is an example of what I was refering to as a not continouos correspondence. Maybe the term is dull, but comparing to how GR reduces to Newtonian gravity for weak fields the term kind of make sense, or at least I hope you get my point. The state of the wave/particle is changed instantly, in a discrete manner.

 

[Kontilera]

Of course, if Im wrong i would be glad to expand/correct my understanding.

 

[Fra]

But it appears to me that, although the theories are (what I as a layman would call) deterministic in their own regime, the process of measurement is not. The transition from wave to particle for a single electron in a dubble slit experiment is an example of what I was refering to as a not continouos correspondence.

Are you thinking about the the relation between probability distributions of events that gives expectations of the future given a preparation, and the actual observed relative frequencies of a finite sequence of random events?

/Fredrik

 

[Kontilera]

Are you thinking about the the relation between probability distributions of events that gives expectations of the future given a preparation, and the actual observed relative frequencies of a finite sequence of random events?

/Fredrik

Im thinking about the collapse of the wave function as an instant event. My understanding is that once we look at the electron, its state shifts instantanously.

 

[Kontilera]

But none the less, there seems to be some nontrivial phenomena in the transition from quantum to classical physics. Just the other day I encountered a discussion including Sabine Hossenfelder regarding "delayed quantum choice eraser" or something like that, where a common perspective was debunked. I dont think theres any reason to go into details. Im just wondering if there is some hope among theoretical physicists that this process actually could provide some kind of clues towards, for example, GUTs.

 

[Fra]

Im thinking about the collapse of the wave function as an instant event. My understanding is that once we look at the electron, its state shifts instantanously.

Wether this is a problem or not depends on the interpretation om QM. There are many threads on this the QM interpretation subforum, and I don't think this needs to be discussed in the context of QG or BTSM. One idea is that the state reduction does not mean the world out there instantly collapses, it just means the observers information is updated.

/Fredrik

 

[Structure seeker]

I like the general direction of your second question. Indeed, the symmetry and all the different ways to look at the core of quantum physics are intriguing. But take care, gravity is not yet quantized - intriguing as it may be, we shouldn't let intrigue lead us. There should be experimentally falsifiable theories that can predict much, not fascinating ideas or beliefs that swallow our interest (string theory landscape, yuck!).

If there's a reason for the many ways to view the most basic physics concepts, I would prefer it to be practical rather than theoretical. If all the most intelligent people come together to aid poor people from starvation, an uneducated poor man with a good heart and one cow can beat all their smart solutions by giving his only cow. I think the ineffable genious that devised the laws of physics made those many ways to view them in order to give us his cow, so to speak: to enable us to use these laws for solving practical problems and make a good living all over the globe.

This symmetry fascination is what gave birth to string theory, actually a framework of so many possible theories/configurations that all hope of finding any practical prediction (except some seemingly logical elementary particles) in it seems very, very far away indeed. And while the symmetries surely mean something, experiments have proven predicted particle after predicted particle wrong.

We could use such a theory but then one that explains things about the experimentally proven Standard Model: why three generations of matter and not more or two? Why quarks, leptons, neutrinos and bosons? Instead of superpartners, it is required that any predicted new particles really show up like the Higgs and that all known particles exist in the theory. Because I am sure that that which really exists will baffle those expecting the best of what fascinates us, because the real thing is in fact so much more than they expected that nobody will be able to grasp even half of its applications.