Constructor Theory and Counterfactuals : A new approach to the basis of Theoretical Physics.

[studiot]

Quote

https://www.quantamagazine.org/with-constructor-theory-chiara-marletto-invokes-the-impossible-20210429/

How to Rewrite the Laws of Physics in the Language of Impossibility

They say that in art, constraints lead to creativity. The same seems to be true of the universe. By placing limits on nature, the laws of physics squeeze out reality’s most fantastical creations. Limit light’s speed, and suddenly space can shrink, time can slow. Limit the ability to divide energy into infinitely small units, and the full weirdness of quantum mechanics blossoms. “Declaring something impossible leads to more things being possible,” writes the physicist Chiara Marletto. “Bizarre as it may seem, it is commonplace in quantum physics.”

...

The goal of constructor theory is to rewrite the laws of physics in terms of general principles that take the form of counterfactuals — statements, that is, about what’s possible and what’s impossible. It is the approach that led Albert Einstein to his theories of relativity. He too started with counterfactual principles: It’s impossible to exceed the speed of light; it’s impossible to tell the difference between gravity and acceleration.

Constructor theory aims for more. It hopes to provide the principles behind a vast class of theories of physics, including the ones we don’t even have yet, like the theory of quantum gravity that would unite quantum mechanics with general relativity. Constructor theory seeks, that is, to provide the mother of all theories

 

This is the meat of the linked article from Quanta Magazine.

Anybody interested in discussing this idea ?

[swansont]

Einstein didn't start with c as a limit that can't be exceeded. He started with c an an invariant. c being a limit is a conclusion that follows later, because the solutions for v>c are imaginary numbers.

 

[studiot]

2 hours ago, swansont said:

Einstein didn't start with c as a limit that can't be exceeded. He started with c an an invariant. c being a limit is a conclusion that follows later, because the solutions for v>c are imaginary numbers.

 

Yes good point.

I haven't yet read the new 2021 book, so I'm keeping an open mind,

and the idea may turn out to be just huff and puff or it may lead somewhere.

So I have tried to give just the unarnished bare bones for all to assess.

[swansont]

33 minutes ago, studiot said:

Yes good point.

I haven't yet read the new 2021 book, so I'm keeping an open mind,

and the idea may turn out to be just huff and puff or it may lead somewhere.

So I have tried to give just the unarnished bare bones for all to assess.

I think this overview is very handwavy*, but seeing as there are some examples given, I'd like to see how one would get to relativity from having a cosmic speed limit (i.e. limiting c but not making it invariant), and without the components that Einstein used to get to Lorenz-Fitzgerald contraction. How would one eliminate the wrong explanations? Seems like they admit this isn't what's actually happening.

You can't have a mother of all theories if that mother isn't giving birth to the theories, and they basically admit that's not what is (or would be) happening. This seems more like a big-picture view where you can make sense of some concepts you didn't necessarily know were related. Something like understanding that continuous symmetries give rise to conservation laws.

 

*I can't tell who is overselling this more, the scientists or the person who wrote the article

[hoola]

under the topic of quantum gravity, she indicates that gravity is responsible for entanglement....and therefore indicates a strong quantum coorelation with it, but does gravity act as the mediator in entanglement? Is this generally accepted? Since gravity is limited in speed to c and entanglement issues seem to surpass that, how could it mediate entanglements?

Edited October 10, 2021 by hoola

[Markus Hanke]

16 hours ago, hoola said:

Since gravity is limited in speed to c and entanglement issues seem to surpass that

Entanglement does not involve any exchange of information, or any kind of action - it’s simply a statistical correlation between measurement outcomes. So there’s no conflict with the principles of relativity.

[studiot]

On 10/10/2021 at 7:25 AM, hoola said:

under the topic of quantum gravity, she indicates that gravity is responsible for entanglement....and therefore indicates a strong quantum coorelation with it, but does gravity act as the mediator in entanglement? Is this generally accepted? Since gravity is limited in speed to c and entanglement issues seem to surpass that, how could it mediate entanglements?

Thank you for your interest. +1

I have not read just over halfway through the book so I am no expert, but here is what the lady says about quantum entanglement, including the difference between quantum entanglement and classical entanglement.

 

 

On 9/28/2021 at 4:32 PM, swansont said:

I think this overview is very handwavy*, but seeing as there are some examples given, I'd like to see how one would get to relativity from having a cosmic speed limit (i.e. limiting c but not making it invariant), and without the components that Einstein used to get to Lorenz-Fitzgerald contraction. How would one eliminate the wrong explanations? Seems like they admit this isn't what's actually happening.

 

Halfway through and my impression is the book contains too much chit chat.

So ideas behind it seem to get rather lost in the noise.

Also there are some non intuitive definitions (as always seems to be th case) to get one's head around.

 

Factuals and counterfactuals are a case in point.

They seem to be defined as follows

Factuals are statments, backed by obervations, of physics phenomena that we know have actually happened/ can actually happen / will actually happen.

So yes they could be conservation laws.

So I suppose they are direct staements about a phenomenon.

Counterfactuals come in two formats.

They are statements that are not forbidden, but have never actually happened ie they could happen, given the right conditions.

Or they are statements expressly forbidding something for instance the impossibility of a pertual motion machine.

So I suppose that they are indirect statements about a phenomenon.

 

The claim is that current Physics is heavily slanted towards factuals.
But (in some cases) it is easier to work in terms of counterfactuals.

 

I am not sure about some of the examples given, but it reminds me of the fundamental theorem of calculus that relates interior properties of a region to the boundary properties.

Here is my simple example

Factual

To draw a circle, fix one end of a string at a centre, pull it tight and rotate the other end about that point.

Counterfactual.

Use the string to do some curve stitching of the tangents and the result will be a circle

 

[swansont]

I have to say, in reading that text, that the author and I differ in our understanding of entanglement. 

Entanglement is not an interaction between two particles. It is, rather, an indication of a past interaction, either with each other or with a common entity (such as parametric downconversion where two photons come from the same atom, or in a decay) The difference in an entangled system is that observing one particle allows you to know the state of the other particle, which is not possible in a classical case. They are right, however, in saying that measuring the particles does not tell you if they were entangled. That correlation requires statistics, which means many measurements.

This explanation does nothing to change my view that they've put the cart before the horse. They have not shown that the  counterfactual leads to an understanding of entanglement.  

[joigus]

I'm sorry to join my voice to those that of the party poopers here, but I'm pessimistic about how you can make "negative principles" (principles of impossibility) the constructive groundwork for physics. They have immense heuristic value as a guide, but sooner rather than later you must assume plausible relations between the variables that implement those principles and make them "natural" or "obvious". So I think it's the other way: Impossibility principles by themselves don't allow you to build.

I've been aware of this quantamagazine big anouncement for a while, but didn't make much of it, TBH. And I wish I were wrong for many reasons. Among others, it is very much in tune with my way of thinking of about 20[?] years ago --which would be a very nice revival of my youth years--, that I gave up on account of not really leading anywhere useful.

"It is impossible to determine position and momentum at the same time" doesn't give you HUP all the way down by any means. Let alone the reason why it's true it works. But maybe there's a lot I ignore about this new idea. And I can give several more examples. Swansont has perfectly illustrated how it works with SR.

Edited October 13, 2021 by joigus

[studiot]

On 10/12/2021 at 11:35 AM, swansont said:

I have to say, in reading that text, that the author and I differ in our understanding of entanglement. 

Entanglement is not an interaction between two particles. It is, rather, an indication of a past interaction, either with each other or with a common entity (such as parametric downconversion where two photons come from the same atom, or in a decay) The difference in an entangled system is that observing one particle allows you to know the state of the other particle, which is not possible in a classical case. They are right, however, in saying that measuring the particles does not tell you if they were entangled. That correlation requires statistics, which means many measurements.

This explanation does nothing to change my view that they've put the cart before the horse. They have not shown that the  counterfactual leads to an understanding of entanglement.  

 

26 minutes ago, joigus said:

I'm sorry to join my voice to those that of the party poopers here, but I'm pessimistic about how you can make "negative principles" (principles of impossibility) the constructive groundwork for physics. They have immense heuristic value as a guide, but sooner rather than later you must assume plausible relations between the variables that implement those principles and make them "natural" or "obvious". So I think it's the other way: Impossibility principles by themselves don't allow you to build.

I've been aware of this quantamagazine big anouncement for a while, but didn't make much of it, TBH. And I wish I were wrong for many reasons. Among others, it is very much in tune with my way of thinking of about 20[?] years ago --which would be a very nice revival of my youth years--, that I gave up on account of not really leading anywhere useful.

"It is impossible to determine position and momentum at the same time" doesn't give you HUP all the way down by any means. Let alone the reason why it's true it works. But maybe there's a lot I ignore about this new idea. And I can give several more examples. Swansont has perfectly illustrated how it works with SR.

Thank you both for these replies.

I have not said that I agree (or disagree) with the lady, but I would be very suprised if Oxford University was barking up a tree as far from the physics forest as you seem to suggest.

In particlar I am finding many of the examples given in the book questionable.

But this is a Science forum and this thread seems to be the only one actually discussing Science at the moment.

 

As regards entanglement, that is only one part of it and I do not fully agree with you guys there.

But then the lady herself indicates that experts disagree on aspects of the subject.

So I have started a new thread specifically about entanglement for deeper discussion and to avoid derailing this thread with side arguments.

 

 

[joigus]

1 hour ago, studiot said:

I have not said that I agree (or disagree) with the lady, but I would be very suprised if Oxford University was barking up a tree as far from the physics forest as you seem to suggest.

I know I'm not British, but I'm more of a Cambridge man, if I had to choose.

To me it's doctor Marlettto, and nothing would please me more than see her idea come to fruition. Maybe it's just the great paradigm change we need.

To me, it's up there with Kelvin's knots, Poincaré's tiny rigid electron, and other ideas. If anything, just much less naive than those of the great men.

But the reason I think it won't work is because impossibility principles are formulated (finally) as logical obstructions. You need the logical framework in order to find the obstruction. Otherwise, what does it obstruct?

[studiot]

25 minutes ago, joigus said:

I know I'm not British, but I'm more of a Cambridge man, if I had to choose.

To me it's doctor Marlettto, and nothing would please me more than see her idea come to fruition. Maybe it's just the great paradigm change we need.

To me, it's up there with Kelvin's knots, Poincaré's tiny rigid electron, and other ideas. If anything, just much less naive than those of the great men.

But the reason I think it won't work is because impossibility principles are formulated (finally) as logical obstructions. You need the logical framework in order to find the obstruction. Otherwise, what does it obstruct?

I don't think I will be buying this book, but I am trying to dig out notions worthy of development for discussion.
 

In particular I am offering my thoughts on what Dr Marletto might be trying to say.

In particular the efficiency of boundary element calculation v those of finite element calculation is well known and documented.

But I may be wrong that her thesis is an spect of that.

I also think you have turned her argument around, perhaps my fault for giving the wrong impression.

Quote

Martello

By contemplating what is possible, in addition to what happens, we have a much more complete picture of the physical world.

So thank you for making me recheck what I am getting out of this book.

 

Edit that's twice just now I've lost connection to the site ( and written work) so I'm giving up for tonight.

Edited October 13, 2021 by studiot