Logic of E-H action, ricci scalar, cosmological constant?

[atyy]

I think this is available free, but I'm not sure.

Gravity: the inside story
T. Padmanabhan
http://www.springer.com/physics/journal/10714
http://www.springerlink.com/content/l403540q87606463/

 

[Fra]

MTd2, thanks for hinting your guiding principles, although I may not understand your logic completely. But it looks somewhat different from mine.

You talk about the 4-manifold - does this mean that you somehow take a 4-manifold as a unquestioned starting point? If so, what is the status of the "information of this manifold"?

atyy, thanks for those links, I'll read them and see what it is. I'm waiting for some books I ordered and until them I've got some slots to read papers.

/Fredrik

 

[MTd2]

what is the status of the "information of this manifold"?

What do you mean by status here?

 

[Fra]

What do you mean by status here?

I mean at what level in the theory is this defined? Is it a background entity assumed to make sense, or is it something emergent as per a described process?

I mean, when we start by "consider a 4D manifold". Is that a fundamental starting point, or can you reduce to introduction of this manifold to something more fundamental?

Edit: Ie. is it the notion of 4D-manifold part of your basic premises for reasoning? Or is the 4D-manifold a result of an interaction or evolution of an observer, that is defined without a manifold?

/Fredrik

 

[Fra]

http://www.springer.com/physics/journal/10714

On first skim those essays seem very well written! I have to print them all and read them carefully.
Thanks again for the link! :)

It seems to be the top 5 of

Gravity Foundation Essay Awards 2008!
1. Gravity: the inside story - T. Padmanabhan
2. Noncommutative gravity, a ‘no strings attached’ quantum-classical duality, and the cosmological constant puzzle - T. P. Singh
3. On the physical interpretation of asymptotically flat gravitational fields - Carlos Kozameh, Ezra T. Newman, Gilberto Silva-Ortigoza
4. Quantum field theory in curved spacetime, the operator product expansion, and dark energy - Stefan Hollands, Robert M. Wald
5. The delocalized effective degrees of freedom of a black hole at low frequencies - Barak Kol

/Fredrik

 

[MTd2]

Or is the 4D-manifold a result of an interaction or evolution of an observer, that is defined without a manifold?

The observer is just a classical concept, so I did not include it in the list... But the 4D should be a kind of minimized action.

Did you notice the similarity between your solution for the probability as a vector in a quantum group space?

 

[MTd2]

Another reason to use the 4-Manifold, besides that we probalby live in one, it is that it probably encodes certain kind of beautiful structures, typicaly found in theories that requires a lot of dimensions, like string theory. One example it is that the classification of many smooth 4-d manifolds requires the use of lattice presentation of the E(8).

Also, note that a string structure is used in 4 dimensions to classify. It is differentiable, but there is no diffeormorphism between structures in with the same topology. In fact, the number of diffeomorphic structures for a given topology can be densly infinite. Its name is Casson Handle.

 

[Fra]

Did you notice the similarity between your solution for the probability as a vector in a quantum group space?

Yes there are direct apparent similarities and indeed my intended simple expression evolves, there will appear what one might see as non-commutative microstructures. But I have never been attracted to mathematics itself, this is why I argue the other way and map out the math.

As for the non-commutative microstructures that will emerge, in the construction I have in mind there is a reason for why the don't commute, and it's that they are both constrained by a common complexity bound. There will be equilibrium between the microstructures which is a solution to a sort of optimation problem. So perhaps it's similar to what you think after all. But again like the random walk / diffusion analogy, I think the route to optimum is more like a random walk. The actual "optimation process" is part of the physics in my thinking.

It seems you think of the observer as classical. It's not quite how I see it. To me the observer is the implicit reference. With observer I don't mean an observer inthe classical sense of "a classical measurement device". An observer can well be uncertain realtive to a second observer.

Anyway, I think there is ALOT of interesting things about this that I hope we will all find out in the future.

/Fredrik

 

[MTd2]

Tell me more about the implicit reference.

 

[Fra]

I am going for a trip the next few days so I won't be much online, but to respond shortly of what I mean.

I have given some thought of all these things in the past, the problem of decomposing the observer and the observed, and it sure is true that in standard QM the measurement device (the observer) is a classical system. This is not good enough for serveral reasons.

Nevertheless my opinon is that the problem is not that we have an observer, because there always is one. The problem is howto define the observer. And the solution I envision to this, is that the observer is continiously evolving. The problem of defining the observer, is thus resulting in an evolution.

So with the implicit reference, I mean that any information is relational, and whenever I make a statement, there is always an imlpicit reference to which that statement relates, and this defines an observer.

It's a bit like Zurek's sentiment that "What the observer knows is inseparable from what the observer is".

This means that in my representation, an observer is technically a system of related microstructures, and this system is the observer. So the information is the identifier of the observer. And information is evolving, and identification of observers are a result of spontaneous structure stable formations which are relations to it's environment.

I am still working on this of course, but it at least responds to your question. I am certainly not ignoring this problem, I take it seriously.

/Fredrik

 

[Fra]

It's a bit like Zurek's sentiment that "What the observer knows is inseparable from what the observer is".

This means that in my representation, an observer is technically a system of related microstructures, and this system is the observer. So the information is the identifier of the observer. And information is evolving, and identification of observers are a result of spontaneous structure stable formations which are relations to it's environment.

An implication of this, is that there is not much sense in the notion that "two different observers has the same information" if we by this also also means that the information has the same confidence levels etc. Because if two observers really have the same information, then the two observers conincide.

The distinction between observers, is measured by their disagreement, which in turn is measured by their interaction. And with observer, I also include any subsystems of the universe. And my idea is to extract from the process of disagreeing (a process of communicating opinions) the structure of interacations.

So my picture is that the laws of physics and the physical interactions, are the laws of information processing and communication. And to incorporate the "observer" in these "interactions" is to include the information processors or transcievers in the communication.

This is to me a generalisation of Einsteins Gravity, in that spacetime itself "responds" to the the dynamics in spacetime. IE. the observers "respond" to the communication that is relative to them. The result are evolving observers. And the observer-observer interactions, analysed starting from the simlpest possible observers and scaling up the complexity, should chart out the structure of all interactions. Classifications will emerge here.

/Fredrik

 

[Fra]

This is to me a generalisation of Einsteins Gravity, in that spacetime itself "responds" to the the dynamics in spacetime. IE. the observers "respond" to the communication that is relative to them. The result are evolving observers.

This also shows the problem. Given the original association the geometry of spactime responds to what's going on relative to it, the missing step was still, exactly how does this relation look like. Einsteins equation is a solution to this in GR.

In this case, the question is, exactly HOW does the interaction "the observer" participates in provides a selection for it's evolution. This is the problem I am trying to solve in my way. At first there is the simple idea of random walking towards some optimum, as per some ME principle, but the interesting part is that the space the walk takes place in is also dynamical, and the optimum is moving. So there is no global optimum, just some strange kind of relational optimum. This is a bit unpredictable and I don't know for sure what will come out of this, but I've already convinced myself that a local speed limit in line with lorentz stuff will be emergent, but this is deformed as everything evolves. I also think a universal attraction of structures will emerge, and I think this can explain gravity. And the supposed "explanation of this attraction" lies in the connection that causes an evolution in the observer, given interactions it participates in.

That is a lineout. But the details are in progress of course. Unfortunately I have not found that awfully many existing papers that is doing just this, although many approaches share elements of tihs.

/Fredrik