Undergrad Physicists who propose that symmetries are emergent?

[Fra]

A complicated hypothesis that explains little is not of much use to anyone.

I symphatize with this! A construct that is more complex, or beeing based on an extremely a priori improbable conditions(ie. unnatural), has little explanatory value. It's merely a reformulation.

(BUT it may sometimes indirectly might lead forward. For example, if you like to think in terms of X, recasting it into X-abstractions may help you with insight. I think we all have our own pet abstractions. This is why reading some of the early work of founders of relativity and QM is interesting, it really gives us a inside view of how they were reasoning towards insight and results. This process is quite different from the purification process that mathematicians may later do, which may "clean things up", express things in a more compact language, but sometimes at the prices of covering up the tracks of the original construction an the physical justifications.)

What is deceptive, is that one can find such, often apparentely "timeless" and eternal "patterns" in special cases, and then get seduced and tempted to apply them outside their domain of justification, and this leads to fallacious reasoning. This insight might get totally lost if you detach the math from physics, refined it and come up with another way of putting it, where you have lost justification to physics and measurement.

This is the idea that Smolin also raised, that "the unreasonable effectiveness of mathematics is precisely because it is limited". For example, all the nice symmetry groups we have in particle physics, their domain of justification is for relatively speaking, events that take place in a small area under short times, and can be repeated by preparations and statistics in a lab, living in a solid classical spacetime. The beatiful symmetries and apparent truths observed here, does not necessarily apply to cosmological scales or cosmological times, or for that matter other assymmetric conditions between observer-observed, such as Planck scale events, or during big bang?

/Fredrik

 

[robwilson]

I symphatize with this! A construct that is more complex, or beeing based on an extremely a priori improbable conditions(ie. unnatural), has little explanatory value. It's merely a reformulation.

(BUT it may sometimes indirectly might lead forward. For example, if you like to think in terms of X, recasting it into X-abstractions may help you with insight. I think we all have our own pet abstractions. This is why reading some of the early work of founders of relativity and QM is interesting, it really gives us a inside view of how they were reasoning towards insight and results. This process is quite different from the purification process that mathematicians may later do, which may "clean things up", express things in a more compact language, but sometimes at the prices of covering up the tracks of the original construction an the physical justifications.)

What is deceptive, is that one can find such, often apparentely "timeless" and eternal "patterns" in special cases, and then get seduced and tempted to apply them outside their domain of justification, and this leads to fallacious reasoning. This insight might get totally lost if you detach the math from physics, refined it and come up with another way of putting it, where you have lost justification to physics and measurement.

This is the idea that Smolin also raised, that "the unreasonable effectiveness of mathematics is precisely because it is limited". For example, all the nice symmetry groups we have in particle physics, their domain of justification is for relatively speaking, events that take place in a small area under short times, and can be repeated by preparations and statistics in a lab, living in a solid classical spacetime. The beatiful symmetries and apparent truths observed here, does not necessarily apply to cosmological scales or cosmological times, or for that matter other assymmetric conditions between observer-observed, such as Planck scale events, or during big bang?

/Fredrik

All that is true. And it is true in pure mathematics too. Going back to the originators of the ideas is always instructive. I just feel that in the case of the standard model symmetries, the mathematical cleaning up process has not been done, and that is where I am trying to help. In the process of cleaning up, one sometimes finds errors, or at least one can iron out some inconsistencies, which is bound to be useful. And I am particularly interested in the question of why the symmetries have such limited domains of applicability - I think in some cases it may be because they have become too abstract, and divorced from experiment. The apparent asymmetry between observer and observed is also something that deserves more attention, in my view.

 

[Fra]

And I am particularly interested in the question of why the symmetries have such limited domains of applicability - I think in some cases it may be because they have become too abstract, and divorced from experiment. The apparent asymmetry between observer and observed is also something that deserves more attention, in my view.

Yes. Early on, one could understand which observer classes symmetries relates to. Ie poincare groip etc. Its then also easy to understand when and why it must hold.

But as structures that are not possible to understand classicaly that emerge as a result of combining relativity with QM, which get graudally worse the more interactions you look at, and you involve internal dof as well as mixing internal and spacetime symmetry in a way that is understood only mathematically and pragmatically, we start to get lost and rightfully get unsure about which symmetries to enforce from physical perspective.

I would argue that to do this, we need to acknowledge that an observer is more than its frame of reference in spacetime ;)

/Fredrik

 

[jake jot]

Yes, spacetime is a pre-requisite for QFT as it stands.
The vacuum is the quantum description of classically "empty space" indexed by a classical spacetime. Without a solid classical background and spacetime it is difficult to justify the construction of quantum mechanics itself.

This is part of the problem.I still don't know which third theory is mentioned in your paper, but yes its possible to entertain speculative reconstructions where 4d spacetime is not a prerequisition. One idea is to consider higher dimensional worlds, where the 4D spacetime can emerge as an approximation. But this is just one idea. One can also picture NO continuous spaces at all, but instead start with more primary concepts, such as various relations or self-organisation in some large complexity continumm limie or low energy limit allows and emergence of 4D spacetime.

So if the question is wether there can be things more primary than 4D spacetime or vacuum then that is possible. But one must realize that once we thow out the classical references, we loose the ground on which QM is constructed. This is the difficult part. One can of course reconstruct QM mathematically without this ground, but then the physical basis is left out and we lost contact to reality and experiment.

/Fredrik

About"But one must realize that once we throw out the classical references, we loose the ground on which QM is constructed. " What "classical references" were you referring too? What ground?

And instead of framing it as whether there can be things more primary than 4D spacetime or vacuum. Maybe the better words is something that may be parallel to 4d spacetime or vacuum. Meaning you don't just unit these two, but an ignored third stuff the universe is constructed of. This is semantically and theoretically sound statement, wrong?

 

[Auto-Didact]

You can always model anything if your model is complicated enough. The trick is to see through the mass of experimental data to the simple core, and come up with a simple hypothesis that explains a lot. A complicated hypothesis that explains little is not of much use to anyone.

This is a strawman argument. When arguing to use dynamics, topology, analysis or geometry as a tool I am specifically not arguing for complicated hypotheses over simple ones. Instead I am arguing for different perspectives which tend to have a completely different, often unconventional, foundation - i.e. unknown to most (not part of a standard curriculum).

Mathematical disciplines that are unknown to many tend also to be slightly intimidating to most, because it might seem to be more complicated than the simple alternative they already know, even if it is conceptually just as simple or even simpler than the more conventional alternative. An example of this is the exterior calculus and differential forms over standard "simpler" vector calculus and multivariable calculus learned in school.

Such "simpler" alternatives are easier in a specific context and purely perceived as generally being simpler due to them already being familiar and spoonfed from a young age, but they are in actuality not really conceptually or mathematically simpler, just different. From the broader mathematical viewpoint, they usually contain assumptions which prevent them from being directly applicable or generalizable to other theories, while the alternative formulations tend to have less or no such problems.

To paraphrase Feynman: "You can't make imperfections on a perfect thing, you need another perfect thing."

An algebraic approach is more likely to find the simple hypothesis - although there is not much evidence that it has been found yet.

This is simply not true in general, and in fact only becomes true once the correct framework has already been identified. But that is precisely the problem we are discussing: how does one identify the correct framework in the first place? What if this framework has not yet been discovered or invented? Algebra itself being non-specific i.e. framework independent is usually of little help in this identification and selection process, especially during the beginning stages.

Discovery of novel frameworks in mathematics is an experimental process of trial and error which requires intuition, not merely computation or deduction; that only comes later once everything has already been worked out. If one is in the beginning stages of creating new mathematical frameworks or generalizing older ones (e.g. the generalization of Euclidean to non-Euclidean geometry) one is typically necessarily unable to use algebra reliably because the correct framework upon which to do algebra simply has yet to be identified.

 

[robwilson]

This is a strawman argument. When arguing to use dynamics, topology, analysis or geometry as a tool I am specifically not arguing for complicated hypotheses over simple ones. Instead I am arguing for different perspectives which tend to have a completely different, often unconventional, foundation - i.e. unknown to most (not part of a standard curriculum).

Mathematical disciplines that are unknown to many tend also to be slightly intimidating to most, because it might seem to be more complicated than the simple alternative they already know, even if it is conceptually just as simple or even simpler than the more conventional alternative. An example of this is the exterior calculus and differential forms over standard "simpler" vector calculus and multivariable calculus learned in school.

Such "simpler" alternatives are easier in a specific context and purely perceived as generally being simpler due to them already being familiar and spoonfed from a young age, but they are in actuality not really conceptually or mathematically simpler, just different. From the broader mathematical viewpoint, they usually contain assumptions which prevent them from being directly applicable or generalizable to other theories, while the alternative formulations tend to have less or no such problems.

To paraphrase Feynman: "You can't make imperfections on a perfect thing, you need another perfect thing."


This is simply not true in general, and in fact only becomes true once the correct framework has already been identified. But that is precisely the problem we are discussing: how does one identify the correct framework in the first place? What if this framework has not yet been discovered or invented? Algebra itself being non-specific i.e. framework independent is usually of little help in this identification and selection process, especially during the beginning stages.

Discovery of novel frameworks in mathematics is an experimental process of trial and error which requires intuition, not merely computation or deduction; that only comes later once everything has already been worked out. If one is in the beginning stages of creating new mathematical frameworks or generalizing older ones (e.g. the generalization of Euclidean to non-Euclidean geometry) one is typically necessarily unable to use algebra reliably because the correct framework upon which to do algebra simply has yet to be identified.

Let me give you an example. Since this is a thread about symmetry, let's discuss the up/down left/right symmetry of spin in the standard model. Isolated from everything else, one only needs the quaternion group of order 8 to describe these symmetries. To take the classical limit of large numbers of spins, one works in the group algebra. The structure of this algebra is (in physics language) a Euclidean spacetime plus four particles. The spacetime also has a multiplication on it, which describes the macroscopic phenomenon of magnetism. Three of the particles have both left and right spins, one of them only has left spin. There is a finite symmetry that gives the weak doublets of the standard model, if we interpret the particles in the natural way as neutrino, electron, proton and neutron. So one gets all the magneto-weak structure of the standard model and classical physics simultaneously, but without mass or charge, just from the quaternion group. Pure algebra, no geometry required. One needs a bit more to get the whole standard model, but not much.

 

[Fra]

About"But one must realize that once we throw out the classical references, we loose the ground on which QM is constructed. " What "classical references" were you referring too? What ground?

The short statement is. You can not by means of usual physicist-reasoning construct QM without classical mechanics concepts. You need a classical measurment device that live in a classical spacetime. You need means to prepare and conduct measurements many times to build statistics to justify the probabllity foundation. Look at how QM was devised. The "certainty" of uncertainty relies on a classical reference.

So qm does not replace classical mechanics. It extends it and allows deaceiptions of "black boxes" I am terms of controlled interactions.

/Fredrik

 

[Auto-Didact]

Let me give you an example. Since this is a thread about symmetry, let's discuss the up/down left/right symmetry of spin in the standard model. Isolated from everything else, one only needs the quaternion group of order 8 to describe these symmetries. To take the classical limit of large numbers of spins, one works in the group algebra. The structure of this algebra is (in physics language) a Euclidean spacetime plus four particles. The spacetime also has a multiplication on it, which describes the macroscopic phenomenon of magnetism. Three of the particles have both left and right spins, one of them only has left spin. There is a finite symmetry that gives the weak doublets of the standard model, if we interpret the particles in the natural way as neutrino, electron, proton and neutron. So one gets all the magneto-weak structure of the standard model and classical physics simultaneously, but without mass or charge, just from the quaternion group. Pure algebra, no geometry required. One needs a bit more to get the whole standard model, but not much.

That is almost a complete non-sequitur. Quaternions, even if today not taught, viewed or recognized anymore as such, are dynamical geometric objects. In other words the quaternion algebra itself is a geometric invention! It is obvious that if one takes the abstract point of view of formal mathematics too seriously, the actual historical context of discovery i.e. the how, why and what of the actual invention or discovery of the mathematics itself gets drowned in the desire for abstraction.

The entire framework of the normed division algebras - of which the quaternion algebra is just an example - is an abstraction of the theory of complex analysis, which itself is arguably the strongest synthesis between all major forms of classical mathematics, more specifically pretty much the ultimate exemplar of the Cartesian unification of algebra and geometry. Every single aspect and operation of the quaternion algebra has a direct geometric interpretation; not taking this to heart because one is able to pretend that it is purely algebraic is the height of self-deception.

This is the danger of formal mathematics for students of mathematics and physics: it completely loses track of what is content, what is process, i.e. what is theory and what is method and pretends that this loss is non-problematic; for theoretical science especially theoretical and mathematical physics - this loss is an attempted suicide of the discipline. The formalist view is a new and unnatural way of doing mathematics in physics, breaking with centuries of tradition. Because it poisons physics - the greatest single source of new mathematics - this in turn poisons the well for mathematics itself.

To quote Atiyah: "Algebra is the offer made by the devil to the mathematician. The devil says: 'I will give you this powerful machine, it will answer any question you like. All you need to do is give me your soul: give up geometry and you will have this marvellous machine."

 

[jake jot]

The short statement is. You can not by means of usual physicist-reasoning construct QM without classical mechanics concepts. You need a classical measurment device that live in a classical spacetime. You need means to prepare and conduct measurements many times to build statistics to justify the probabllity foundation. Look at how QM was devised. The "certainty" of uncertainty relies on a classical reference.

So qm does not replace classical mechanics. It extends it and allows deaceiptions of "black boxes" I am terms of controlled interactions.

/Fredrik

Classical mechanics are effective theory of quantum theory and valid for their domain of applicability. But your statement is perplexing. Again quoting it

"So if the question is whether there can be things more primary than 4D spacetime or vacuum then that is possible. But one must realize that once we throw out the classical references,"

If there are things more primary than 4D spacetime and vacuum, why would that throw out the classical references? What were you referring to? The classical world is still there.

Perhaps there are many ways to frame the more primary thing.

1. like in string theory where spacetime and vacuum were created by vibrations of the strings

2. spacetime and vacuum co existing with another reality unknown to physics

3. more primary thing that pulls off spacetime and QM. I think you were referring to this? But why would it bypass the classical world, the classical word being coarse graining of the quantum world, kindly elaborate this, thanks.

 

[robwilson]

That is almost a complete non-sequitur. Quaternions, even if today not taught, viewed or recognized anymore as such, are dynamical geometric objects. In other words the quaternion algebra itself is a geometric invention! It is obvious that if one takes the abstract point of view of formal mathematics too seriously, the actual historical context of discovery i.e. the how, why and what of the actual invention or discovery of the mathematics itself gets drowned in the desire for abstraction.

The entire framework of the normed division algebras - of which the quaternion algebra is just an example - is an abstraction of the theory of complex analysis, which itself is arguably the strongest synthesis between all major forms of classical mathematics, more specifically pretty much the ultimate exemplar of the Cartesian unification of algebra and geometry. Every single aspect and operation of the quaternion algebra has a direct geometric interpretation; not taking this to heart because one is able to pretend that it is purely algebraic is the height of self-deception.

This is the danger of formal mathematics for students of mathematics and physics: it completely loses track of what is content, what is process, i.e. what is theory and what is method and pretends that this loss is non-problematic; for theoretical science especially theoretical and mathematical physics - this loss is an attempted suicide of the discipline. The formalist view is a new and unnatural way of doing mathematics in physics, breaking with centuries of tradition. Because it poisons physics - the greatest single source of new mathematics - this in turn poisons the well for mathematics itself.

To quote Atiyah: "Algebra is the offer made by the devil to the mathematician. The devil says: 'I will give you this powerful machine, it will answer any question you like. All you need to do is give me your soul: give up geometry and you will have this marvellous machine."

Ah well. You obviously "know" what is right. Certainty is the enemy of progress. Doubt is the key to discovery.

 

[bayakiv]

@ robwilson, You will not object to the fact that any associative algebra is isomorphic to some matrix algebra and the corresponding algebra of linear vector fields. Therefore, the geometry of vector fields corresponding to the algebra of a physical object is not arbitrary, but is determined by a certain dynamic principle of stability (minimality) of these fields in a suitable space. Another thing is that here we have to choose a suitable space and a suitable dynamic principle. In addition, here we are also faced with the philosophical question of the interpretation of vector fields.

 

[robwilson]

@ robwilson, You will not object to the fact that any associative algebra is isomorphic to some matrix algebra and the corresponding algebra of linear vector fields. Therefore, the geometry of vector fields corresponding to the algebra of a physical object is not arbitrary, but is determined by a certain dynamic principle of stability (minimality) of these fields in a suitable space. Another thing is that here we have to choose a suitable space and a suitable dynamic principle. In addition, here we are also faced with the philosophical question of the interpretation of vector fields.

Do I understand correctly that you are choosing a spacetime and dynamics in which to put your vector fields? In my view, spacetime is emergent, so that we do not have the luxury of choosing one.

 

[Fra]

Classical mechanics are effective theory of quantum theory and valid for their domain of applicability. But your statement is perplexing. Again quoting it

"So if the question is whether there can be things more primary than 4D spacetime or vacuum then that is possible. But one must realize that once we throw out the classical references,"

If there are things more primary than 4D spacetime and vacuum, why would that throw out the classical references? What were you referring to? The classical world is still there.

Perhaps there are many ways to frame the more primary thing.

1. like in string theory where spacetime and vacuum were created by vibrations of the strings

2. spacetime and vacuum co existing with another reality unknown to physics

3. more primary thing that pulls off spacetime and QM. I think you were referring to this? But why would it bypass the classical world, the classical word being coarse graining of the quantum world, kindly elaborate this, thanks.

Yes. The classical world is here of course, and it will continuous to be the main based of human science.

Atomic and subatomic physics are operationally defined in terms of controlled measurements in a classical macroscopic laboratory with classical detectors. From our macroscopic perpective, what is going on in the subatomic domain is not something we can directly observe. All observations are indirect, and in this respect the microstructure of matter constitutes a "black box" from the macro-perspecive. In principle the laboratory has all the requiers computations recourse to decode even the most strange information encoded in interactions with this black box system. We can also assume that the timescale of the black box dynamics are small, relative to the timescale of the observing context.

Given this assymmetry, we have developed quantum mechanics, and its formalism, and it shines! This is not what the discussion is about, and in this context the classical background is necessary. Its important to not forget that, and its not a problem per see.

The problem is when this assymmetry is no longer valid, that all conclusions, rules and laws inferred from QM does not apply! We reach these assymmetric cases when we look at cosmology in a quantum mechanical setting. One also touches opone this this assymmetry if one attempts to transform the laws of physics from the macro scale down to Planck scale, where it is not obvious wether primordal structures "see" spacetime as we know it. It might well be that the notion of the spacetime continiuum breaks down here, and that alone makes using the conventional approach to unification difficult, because the notion of the choice of background becomes ambigous (in the scaling scenario).

There are many possible abstractions one can use. Geometric abstractions have been very successful, in many domains of physics. But for these new questions, i personally find the geometric pictures to not be helpful. It doesn't mean it can't work, I just personally find them akward and outdated.

(Not to diverge into this, just to illustrate that choice of abstractions matters: I rather think in terms of interacting agents. The "environment" of one agent, is simply all the other agents. These have simiar relations as constructing principles of GR. One says, matter tells spacetime how to curve, and spacetime tells matter how to move. In this new abstration, its the agents "picture" of the environment that detemines its actions - and vice versa. But we also have that the response from the environment, puts an evolutionary pressure on the agents microstructure. This leas to a quite different "abstraction" that geometry. In this abstraction, QM as it stans corresponds to one DOMINATING agent, literally controlling the environment and boundary of a small system (say an atom), but in my abstraction here you easily see that its a special case. An important special case! but still. )

Perhaps there are many ways to frame the more primary thing.

1. like in string theory where spacetime and vacuum were created by vibrations of the strings

2. spacetime and vacuum co existing with another reality unknown to physics

3. more primary thing that pulls off spacetime and QM. I think you were referring to this? But why would it bypass the classical world, the classical word being coarse graining of the quantum world, kindly elaborate this, thanks.

Yes I think of 3, but to give ST some benefit of doubt, there IS a possible way to connect my outlined thinking with string theory. And that would be to explain the evolution process of selection of the background. That way the "string" can in principle be interpreted as the primordal observer; and that the emergent erlations of interacting strings can be shown to SELECT and single out a certain space time. This is the only reason I've kept a think thread of interested in string theory, but i have not seem much real string theoreists entertain this in a serious way, beyond generic discussions. And i think the fact that string relies on the continuum is a mistake.

/Fredrik

 

[jake jot]

Yes, spacetime is a pre-requisite for QFT as it stands.
The vacuum is the quantum description of classically "empty space" indexed by a classical spacetime. Without a solid classical background and spacetime it is difficult to justify the construction of quantum mechanics itself.

This is part of the problem.I still don't know which third theory is mentioned in your paper, but yes its possible to entertain speculative reconstructions where 4d spacetime is not a prerequisition. One idea is to consider higher dimensional worlds, where the 4D spacetime can emerge as an approximation. But this is just one idea. One can also picture NO continuous spaces at all, but instead start with more primary concepts, such as various relations or self-organisation in some large complexity continumm limie or low energy limit allows and emergence of 4D spacetime.

So if the question is wether there can be things more primary than 4D spacetime or vacuum then that is possible. But one must realize that once we thow out the classical references, we loose the ground on which QM is constructed. This is the difficult part. One can of course reconstruct QM mathematically without this ground, but then the physical basis is left out and we lost contact to reality and experiment.

/Fredrik

For reference, the third theory I'm referring to is from the following. Quoting the book "Physics meets Philosophy at the Planck Scale" about approaches to quantum gravity:

"1. Quantising General Relativity
2. Quantising a different classical theory, while still having general relativity emerge as a low- energy (large-distance) limit.
3. Having general relativity emerge as a low-energy limit of a quantum theory that is not a quantization of a classical theory
4. having both general relativity and quantum theory emerge from a theory very different from both"

I was referring to the 4th. Having both general relativity and quantum theory emerge from a theory very different from both. But is it not most accept that GR and QFT are just effective theory? I'm looking for some kind of Transformation where GR and QFT can be overidden such that the deeper theory takes over (for example, using GR there is no way to travel faster than light. But using the deeper theory. We can do much more).

 

[bayakiv]

Do I understand correctly that you are choosing a spacetime and dynamics in which to put your vector fields? In my view, spacetime is emergent, so that we do not have the luxury of choosing one.

That's right, space-time is emergent. And it is proposed to choose not space-time, but space, in which the vector field of accelerations of moving matter (in other words, Aether) is given. Look at thread Geometry of matrix Dirac algebra , where 8-dimensional Euclidean space is tried on for this role.

 

[robwilson]

That's right, space-time is emergent. And it is proposed to choose not space-time, but space, in which the vector field of accelerations of moving matter (in other words, Aether) is given. Look at thread Geometry of matrix Dirac algebra , where 8-dimensional Euclidean space is tried on for this role.

Fair enough. I've also been down that road, though in more algebraic language, and the group-theoretical perspective is discussed in my recent papers on the arxiv.

 

[bayakiv]

Fair enough. I've also been down that road, though in more algebraic language, and the group-theoretical perspective is discussed in my recent papers on the arxiv.

Wonderful! Then it remains to solve the inverse problem - to determine the shape of their vector fields by the algebraic-group properties of elementary particles. However, it is also important to know why one form is stable, and the other quickly breaks down into stable forms.

 

[Fra]

4. having both general relativity and quantum theory emerge from a theory very different from both"

I was referring to the 4th. Having both general relativity and quantum theory emerge from a theory very different from both. But is it not most accept that GR and QFT are just effective theory? I'm looking for some kind of Transformation where GR and QFT can be overidden such that the deeper theory takes over (for example, using GR there is no way to travel faster than light. But using the deeper theory. We can do much more).

This could be possible probably in several way.

LQG in small parts attempts some of this, but the approach is not radical enough and has no ambition to account for other forces. and it uncritically brings in quantum formalism in an inappropriate way imo.

My way of thinking here is if you start from building blocks of the smallest possible distinghuishable matter or agents, with certain interaction rules that only defines interactions with the environment.Then try to show that when these parts self-organize, spacetime as we know it emerge spontaneously. And along with this internal and mixe internal/external transformations endcode other forces. Interacting agents would fall in this category. Its the population and emergent evolved communication that should (as per the conjecture) encode matter contents and the laws of physics. All this presumes not 4D spacetime, nor GR in its starting poits. Instead a universal attraction, as well as locality is built into the design. It remaines however to show that the "residual universal attraction" that is left once you "shave off" the other forces, is GR in the low energy cosmo scale. In this case, gravity can also be seen as the residual entropic forces, once the internal interactions are separated. But I am not aware of much papers to direct to, where this is well develped.

/Fredrik

 

[jake jot]

This could be possible probably in several way.

LQG in small parts attempts some of this, but the approach is not radical enough and has no ambition to account for other forces. and it uncritically brings in quantum formalism in an inappropriate way imo.

My way of thinking here is if you start from building blocks of the smallest possible distinghuishable matter or agents, with certain interaction rules that only defines interactions with the environment.Then try to show that when these parts self-organize, spacetime as we know it emerge spontaneously. And along with this internal and mixe internal/external transformations endcode other forces. Interacting agents would fall in this category. Its the population and emergent evolved communication that should (as per the conjecture) encode matter contents and the laws of physics. All this presumes not 4D spacetime, nor GR in its starting poits. Instead a universal attraction, as well as locality is built into the design. It remaines however to show that the "residual universal attraction" that is left once you "shave off" the other forces, is GR in the low energy cosmo scale. In this case, gravity can also be seen as the residual entropic forces, once the internal interactions are separated. But I am not aware of much papers to direct to, where this is well develped.

/Fredrik

It's highly plausible our attempt to unify QFT and GR is like scientists at the time of Newton trying to unify space and matter when they didn't even know matter was composed of atoms.

Our physicists were so entranced by QFT and GR. Although they can explain many things. It can't explain all. I'll take the case of Hossenfelder. She critiqued many particle physicists, saying they are lost in math (title of her book). But she is also a victim. Trapped by Standard model thinking. She thought the world is all there is to it. So all most of our top physicists in the world.

I guess it's hopeless now. We may have to wait for 50 years or more when the next generations of more open minded physicists were born.

Meantime, I can't blame many physicists going into banking and other fields. As some feel it's a dead end. It is for our generation physicists.

I just hope the future would have the environment for the new generations of physicists. And not a dark future where climate change, wars, political unrests, chaos make the work of the new physicists not even possible. If so, then the physicists in this generation may be the last chance. But blind are they. Such despair, such hopelessness.

 

[bayakiv]

I just hope the future would have the environment for the new generations of physicists. And not a dark future where climate change, wars, political unrests, chaos make the work of the new physicists not even possible. If so, then the physicists in this generation may be the last chance. But blind are they. Such despair, such hopelessness.

On the contrary, scientific revolutions were often accompanied by various cataclysms.

 

[jake jot]

This could be possible probably in several way.

LQG in small parts attempts some of this, but the approach is not radical enough and has no ambition to account for other forces. and it uncritically brings in quantum formalism in an inappropriate way imo.

My way of thinking here is if you start from building blocks of the smallest possible distinghuishable matter or agents, with certain interaction rules that only defines interactions with the environment.Then try to show that when these parts self-organize, spacetime as we know it emerge spontaneously. And along with this internal and mixe internal/external transformations endcode other forces. Interacting agents would fall in this category. Its the population and emergent evolved communication that should (as per the conjecture) encode matter contents and the laws of physics. All this presumes not 4D spacetime, nor GR in its starting poits. Instead a universal attraction, as well as locality is built into the design. It remaines however to show that the "residual universal attraction" that is left once you "shave off" the other forces, is GR in the low energy cosmo scale. In this case, gravity can also be seen as the residual entropic forces, once the internal interactions are separated. But I am not aware of much papers to direct to, where this is well develped.

/Fredrik

Do you know of arxiv topics about what sits behind space and matter? I read this in old archive at PF in 2005. The subtle title is controversial so let's not discuss it, except this part only.

Like Einstein said, there is no absolute space, space is an extension of matter. Space is not primary, nor fundamental, it does not exist by itself, it is a product, just as matter and time are products. Space is dynamic, it fluctuates, it tells matter where to go and matter tells it how to curve, remember? Empty space, on the other hand, is primary. You see, there is empty space and then there is material space, a mix of ZPR and CMBR particles. Einstein' spacetime is packed full of photons, that is where Inflation, the time cone, the time arrow, the Big Bang, 'false vacuum', etc., all come from. This why we now say space is grainy.

Locality, in spacetime, is a relation. Objects are relative to other objects, not to empty space.

The field is not to be seen as the ultimate irreducible reality, empty space is. But information starts with the field... with first quantum of action.

When we think about empty space we should stay away from notions that imply motion. Terms like infinity or velocity, size or duration... are not applicable. In this realm, we must think in terms of state, not in terms of process. Process happens in spacetime.

Because the aether is not composed of parts that follow a time line and the idea of motion is not applicable, we can safely say that the aether is one. Because it is one, there is no need for motion, there is no space or distance to cover, this is where non-locality and EPR phenomena come from. State, not knowledge, is registered throughout the Universe instantaneously, Mach was right."

Source https://www.physicsforums.com/threads/the-classical-aether-vs-the-modern-vacuum.187117/page-3

Do you agree with the first sentence above that "Like Einstein said, there is no absolute space, space is an extension of matter."? This is a good punchline, space being an extension of matter. So there must be something beside space and matter (the treatise above simply calls it "empty space". To make it not a philosophical thing. I want to know how it would behave if the more primary thing has its own forces of nature that we can access within space and matter (or mathematically within spacetime and QFT). Are there arxiv theoretical physicists who dig this or none of them write such?

I know "empty space" and "aether" can be seed for mass confusion. So let's not discuss them especially the latter. But maybe refer it to "the unname". In the same thread. It concludes with

"
This notion of a primordial substance is a very old one, also known as Akasha or Brahman, and many times described as pure energy or spiritual fire. It has been anthropomorphized by man since the times of Plato and Aristotle, the Chaldeans and the Akkadians. It has been called by the names of Zeus, Jupiter, Brahma and other.

We are talking about a notion, not just a word."

Source https://www.physicsforums.com/threads/the-classical-aether-vs-the-modern-vacuum.187117/page-3

That's right. Let's not fight over a word, so just refer it as the "unname" (behind space and matter).

 

[robwilson]

Wonderful! Then it remains to solve the inverse problem - to determine the shape of their vector fields by the algebraic-group properties of elementary particles. However, it is also important to know why one form is stable, and the other quickly breaks down into stable forms.

Exactly. That is what I am working on. I'll let you know if/when I find an answer worth sharing.

 

[Auto-Didact]

Ah well. You obviously "know" what is right. Certainty is the enemy of progress. Doubt is the key to discovery.

I understand the value of doubt and uncertainty; this is exactly why I'm so skeptical of putting too much unwarranted trust in the precise formal rigorous calculational method of algebraic reasoning, which while fully exact simply may not have any actual meaning whatsoever by being wholly disembodied and disconnected from the world.

Contrast this with the intuitive, essentially uncertain and open-ended nature of geometry and dynamics which, while uncertain and sometimes even vague, does seem to be capable of embracing the world. In any case, I think we actually agree on far more than that we disagree on, even if superficially this may not seem to be so, so no harm done, carry on.

 

[Fra]

Meantime, I can't blame many physicists going into banking and other fields. As some feel it's a dead end. It is for our generation physicists.

Part of the this problem is social and political. To have the passion to work on the open problem just for the sake of intellectual stimulation is one thing. To have the wish be become a professional researcher is another thing. These two things unfortunately interfere, because even a the most passionate person needs food on the table, and the professional also need to "stay in business". This interference is quite possibly not good for the development.

(I am one of those that was told face to face by a former supervisor in power to hire or note hire that "if you want a job in this field, you must study string theory". The problem is not that there exists a person that has this view, the problem is that it is allowed and self-inforcing in the system.)

Set aside this problem, I am optimistic! But progress is slow, as long as most manhours are barking up the wrong tree (the money tree?).

/Fredrik

 

[bayakiv]

Exactly. That is what I am working on. I'll let you know if/when I find an answer worth sharing.

Some answers may require connecting dynamic principles. If you are interested in my interpretation of the principle of least action in terms of the minimality of a vector field, then look at the very beginning of the book "Mathematical Notes on the Nature of Things".

 

[jake jot]

Do you know of arxiv topics about what sits behind space and matter? I read this in old archive at PF in 2005. The subtle title is controversial so let's not discuss it, except this part only.
Do you agree with the first sentence above that "Like Einstein said, there is no absolute space, space is an extension of matter."? This is a good punchline, space being an extension of matter. So there must be something beside space and matter (the treatise above simply calls it "empty space". To make it not a philosophical thing. I want to know how it would behave if the more primary thing has its own forces of nature that we can access within space and matter (or mathematically within spacetime and QFT). Are there arxiv theoretical physicists who dig this or none of them write such?

I know "empty space" and "aether" can be seed for mass confusion. So let's not discuss them especially the latter. But maybe refer it to "the unname". In the same thread. It concludes with

"
This notion of a primordial substance is a very old one, also known as Akasha or Brahman, and many times described as pure energy or spiritual fire. It has been anthropomorphized by man since the times of Plato and Aristotle, the Chaldeans and the Akkadians. It has been called by the names of Zeus, Jupiter, Brahma and other.

We are talking about a notion, not just a word."

Source https://www.physicsforums.com/threads/the-classical-aether-vs-the-modern-vacuum.187117/page-3

That's right. Let's not fight over a word, so just refer it as the "unname" (behind space and matter).

Fra, I think the reason it is incorrect to state that space is extension of matter is the following arguments?

The Road to Relativity: The History and Meaning of Einstein's "The ... - Hanoch Gutfreund, Jürgen Renn - Google Books

quoting a tiny part of Forword to get in the mood:

Instead of thinking of space and time as a stage, on which the drama of matter unfolds, we have to imagine some ultra-modern theater, in which the stage itself becomes one of the actors.

step 1 may be put this way: There is no such thing as an empty stage without actors on it.

2. Continuing this methaphor, we can say that these space-time structures no longer form a fixed stage, on which different drames of matter and fields may be enacted: stage and actors interact. A new drama requies a new stage. Not only is the local structure (in the sense of a finite path) of space-time dynamized, but the global structure (in the sense of the entire manifold topology) is no longer given a priori. For each solution to the gravitational field equations given locally, one must work out the global topology of the maximally extended manifolds(s) compatible with these local space-time structure.

3. Finally, the stage has no properties of its own that are independent of the action. The same drama cannot be enacted on different parts of the stage: as the actors move about, they carry the stage along with them. Expressed less metaphorically, the points of the bare manifold have no inherent properties that distinguish one point from another; rather, all such distinctions depend on the presence of fields and matter. Many textbooks on general relativity still refer to these bare points as "events," incorrectly suggesting that, as in all previous physical theories, the points are physically individuated a priori, thus obscuring this truly revolutionary feature.

What textbooks made such mistakes? Could it be because it's still controversial?

It sounds very elegant. But that's not reason to think that spacetime is fundamental or just Loop Quantum Gravity.

 

[Auto-Didact]

Some answers may require connecting dynamic principles. If you are interested in my interpretation of the principle of least action in terms of the minimality of a vector field, then look at the very beginning of the book "Mathematical Notes on the Nature of Things".

To what extent does your interpretation relate to the idea that the principle of least action is mathematically speaking just a direct consequence of the generalized Stokes' theorem for one-forms on symplectic manifolds?

 

[bayakiv]

To what extent does your interpretation relate to the idea that the principle of least action is mathematically speaking just a direct consequence of the generalized Stokes' theorem for one-forms on symplectic manifolds?

As far as I understand, the space of coordinates and momenta can be combined in a symplectic manifold, and then the principle of least action can be interpreted as you said, but if the momentum is considered as a derivative value that arises as a characteristic of the motion of a singularity of a vector field in the Finsler product of two Minkowsky spaces with an inverse metric, then the principle of least action should be interpreted for differential forms in 8-dimensional space with a neutral metric.

 

[Fra]

...
Many textbooks on general relativity still refer to these bare points as "events," incorrectly suggesting that, as in all previous physical theories, the points are physically individuated a priori, thus obscuring this truly revolutionary feature.
...
What textbooks made such mistakes? Could it be because it's still controversial?

Textbooks have different levels of ambitions, some introduce things more or less quasi-axiomatically, in order to present the mathemathical machinery. Some have a historical approach.

I personally don't see a problem with the notion of an event, the bigger question is what structure and ontology you assign to the set of events. In my terminology, an event is defined relative to an observer (frame), and its INDEXED by spacetime. That in itself need not make any claim of the ontological meaning of this spacetime. Ie. it certainly need not imply its a "physical point".

In my view, the spacetime index, is implicitly encoded in the structure of the matter, and the "worldview" one piece of matter has about the remainder of the universe, is likely encoded in itself, in a hologhraphic sense (thats not to claim anything about hologhraphic principle). In this view, spacetime is implicit in the CODE of matter. What remains to be explained, is why the - a priori indepdendent codes - evolved to be consistent (and to form equivalence classes or of SR and GR).

/Fredrik

 

[Fra]

If you are interested in LQG. Check this old thread, of my own ponderings when started with Rovellis book analysing his constructing principles (before wasting time on technical deails).

https://www.physicsforums.com/threa...able-in-classical-and-quantum-gravity.220841/

/Fredrik