## Interesting Paper On Quantum Gravity

I just finished reading this paper, and have a question:

CAUSAL SITES AS QUANTUM GEOMETRY
J. DANIEL CHRISTENSEN AND LOUIS CRANE
Abstract.

http://arxiv.org/PS_cache/gr-qc/pdf/0410/0410104.pdf

We propose a structure called a causal site to use as a setting for quantum geometry, replacing the underlying point set. The structure has an interesting categori-cal form, and a natural “tangent 2-bundle,” analogous to the tangent bundle of a smooth manifold. Examples with reasonable finiteness conditions have an intrinsic geometry, which can approximate classical solutions to general relativity. We propose an approach to quantization of causal sites as well.

http://arxiv.org/PS_cache/gr-qc/pdf/0410/0410104.pdf

Can anyone define a "tangent 2-bundle?" in plain English?

Thanks!!

 Quote by MistyMountain Can anyone define a "tangent 2-bundle?" in plain English?
No. It requires quite a bit of mathematics. Have a look at the String Coffee Table http://golem.ph.utexas.edu/string/index.shtml which is run by a 2-gauge theory person: Urs Schreiber. This site has a lot of recent mathematical links on 2-categorical ideas.

Kea

 Quote by Kea No. It requires quite a bit of mathematics. Have a look at the String Coffee Table http://golem.ph.utexas.edu/string/index.shtml which is run by a 2-gauge theory person: Urs Schreiber. This site has a lot of recent mathematical links on 2-categorical ideas. Kea
Hello there!

I have had a lot of mathematics, including advanced courses in differential geometry, group theory, and algebra.

I have won several awards and have worked iwth Nobel laureates.

I am sure that if you give a valid explanation, I will understand it.

Physics is supposed to make sense on a physical level, and these are physics forums.

So if "tangent 2-bundle" has no physical meaning, then just say so, and we can delete this thread from this forum, which is, after all, a physics forum.

But if it does have a physical meaning, please describe.

Thanks!

## Interesting Paper On Quantum Gravity

 Quote by MistyMountain So if "tangent 2-bundle" has no physical meaning, then just say so....
At this point in time and here, it has no physical meaning. However, intuitively, in the same way that ordinary tangent bundles turn up everywhere in physics one can think of 2-bundles as a Stringy analogue. Instead of associated bundles of a principal bundle based on a group, one considers instead notions of 2-groups or 2-groupoids. The former of these turns out to be the same thing as a crossed module, but more importantly, a 2-group is a group object in the category of groups, a description that highlights the idea of internalisation, which is crucial in the higher categorical approaches to QG.

With a good maths background, after some study of category theory this should become quite clear.

Cheers
Kea
 **Hello there! I have had a lot of mathematics, including advanced courses in differential geometry, group theory, and algebra. ** Every grad student gets that in these days **I have won several awards and have worked iwth Nobel laureates. ** In dimensions 4 - 7 I guess ** I am sure that if you give a valid explanation, I will understand it. ** No, if you were really that brilliant, you would figure it out yourself in 30 minutes Cheers, Careful
 To the moderators: Why is Careful allowed to personally insult me while never answering the questions at hand, advancing knowledge in the physical arena, nor ever posting any links to any references? What exactly is going on here?

 Quote by Kea At this point in time and here, it has no physical meaning. However, intuitively, in the same way that ordinary tangent bundles turn up everywhere in physics one can think of 2-bundles as a Stringy analogue. Instead of associated bundles of a principal bundle based on a group, one considers instead notions of 2-groups or 2-groupoids. The former of these turns out to be the same thing as a crossed module, but more importantly, a 2-group is a group object in the category of groups, a description that highlights the idea of internalisation, which is crucial in the higher categorical approaches to QG. With a good maths background, after some study of category theory this should become quite clear. Cheers Kea
Thanks!

I see--it has no physical meaning.

But then it puzzles me as why SelfAdjoint linked to it as an answer to these questions:

I am looking for papers on String Theory, or LQG, that:

1) model a fundamental physical reality from which both quantum mechanics and relativity descend.

2) offer a simple postulate which accounts for a deeper physical reality from which both quantum mechanics and relativity descend.

3) offer a simple postulate and/or physical model which simultaneously accounts for quantum entanglement and relativity's two postulates.

PLEASE NOTE MY USE OF THE WORD PHYSICAL IN ALL THE ABOVE.

Thanks!

I forgot to mention that M-theory papers accomplishing the above would also be of great interest.

Thanks!!

 Quote by MistyMountain But then it puzzles me as why SelfAdjoint linked to it....
MistyMountain

People are being terse with you because you have upset them, for a number of reasons, such as

1. Lack of PF etiquette: it is quite unnecessary to repeat yourself or to make grandiose claims that have no relevance to the conversation.

2. Some people are old and they forget what it's like to be young. You shouldn't reprimand them for this: you should understand it.

3. You have started more than one thread on topics that have either been discussed previously, or are of little interest. For instance, there was a thread on the CC paper earlier. It would have been more appropriate to find it rather than begin your own.

Cheers
Kea

 Quote by Kea MistyMountain People are being terse with you because you have upset them, for a number of reasons, such as 1. Lack of PF etiquette: it is quite unnecessary to repeat yourself or to make grandiose claims that have no relevance to the conversation. 2. Some people are old and they forget what it's like to be young. You shouldn't reprimand them for this: you should understand it. 3. You have started more than one thread on topics that have either been discussed previously, or are of little interest. For instance, there was a thread on the CC paper earlier. It would have been more appropriate to find it rather than begin your own. Cheers Kea

Thanks Kea,

I don't enjoy repeating myself, but it seems nobody wants to answer my questions regarding physics here, which is kindo ironic, when one considers the name of this site. That's just the way it is. I have made peace with it.

I have made no grandiose claims.

All I've said is that logic and reason have lead me to a physical theory which accomplishes the grandiose claims that have been made by stringtheory, LQG, and M-theory, but for which no actual physical papers exist. It appears that ST, MT, and LQG have foresaken logic and reason, and are now paying the price. I guess I understand why some people are upset, but please do not take it out on me--I never pulled the wool over your eyes--that was Greene, Witten, Kaku, and the NSF.

Sorry that some people are old here. At what age will I start insulting people personally? What age did Einstein give up on physics, Truth, and Beauty, in order to insult people--people with honest, genuine questions regarding physics?

Your definition of etiquette makes about as much sense as string theory.

I am embarrassed for modern physics.

 Quote by MistyMountain To the moderators: Why is Careful allowed to personally insult me while never answering the questions at hand, advancing knowledge in the physical arena, nor ever posting any links to any references? What exactly is going on here?
Let me tell you that I myself have rather non standard views on things; but unlike you

(a) I do respect standard science and by far do not claim that my way of thinking leads to Walhalla. I merely want to convey to people why it is a legitimate path and at the same time I give them some of my private thoughts why I think the standard way is NOT going to lead to unification.
This leads sometimes to heated debates (as Kea knows), but we all learn from this.

(b) I always gives references when I see that the other party shows genuine interest and makes intelligent remarks/comments. You must understand that I cannot make the effort each time of looking up the relevant papers (which I have read previously). Usually, I give the author and an Arxiv search is enough for the reader to trace the papers back.

(c) I treat ALL comments people make, also the ones where I have to admit that I am not sure myself.

(d) Unlike you, I am not blaming string theory/LQG for the hard times I have expressing (even peer reviewed and written by respected scientists) alternative views.

(e) I do never speak about my background; never use arguments of authoroty and certainly do not lie about it.

Cheers,

Careful

 Quote by MistyMountain All I've said is that logic and reason have lead me to a physical theory which accomplishes the grandiose claims....
And you've said this a number of times, without actually telling us any physics. I also doubt very much that what you say is true. If you had such a theory you would not have been so ready to use the word interesting in the title of this thread: you would be too busy publishing the details of the rigorous formulation of the SM.
 Misty, I think you are angry and you have every right to be. It is a frustrating time for physics. There has been very little progress recently. However I think your frustration isn't helping. Kea pointed out that the concept was mathematical, and you seemed to take this as a personal insult. Ask someone you like to read your response and explain why it was aggressive, if it didn't seem so to you. As for the mathematical versus physical debate, this goes back to the work of James Clerk Maxwell. Faraday was mocked for his physical explanations, but Maxwell and Faraday were good friends and Maxwell thought in terms of physical models, but managed to express his ideas in terms of mathematics. Newton admitted he had no idea what gravity actually was. The gist seems to be that physical models are rooted in our real world experience, and help individual thinkers, but mathematical models can transcend the limitations of our physical experiences and intuitions. Have hope though - a pile of experimental evidence is building up - especially in the field of cosmology - that undermines current orthodoxy. This evidence will reach critical mass - and physics will have another golden age. Stay calm - don't take yourself too seriously - and you could be part of this golden age..
 Rock on brothers from different mothers! I'm having the time of my life. Not even Brian Greene knows what it's like to unify SR, GR, and QM with a simple postulate, and he has a TV show and several million of our dollars courtesy of the NSF. I just wish that we were allowed to discuss physics here in addition to 1) hurling insults at young physicists 2) posting links to meaningless, red-herring papers that serve no purpose but to fool granting agencies into forking over more money for nonsensical theories. That kinda stuff bores the bejesus out of me. Physics rocks!!! I can hardly wait to post my theory here, but first I need a guarantee that it will be examined in the context of physics, and not in some arbitrary kangaroo court manned by NSF funded hacks, kool-aid addicts, and people with axes to grind. I know it's after Christmas, and nobdoy owes me nuthin', but I still believe in Santa Clause, so again I ask: I am looking for papers on String Theory, or LQG, that: 1) model a fundamental physical reality from which both quantum mechanics and relativity descend. 2) offer a simple postulate which accounts for a deeper physical reality from which both quantum mechanics and relativity descend. 3) offer a simple postulate and/or physical model which simultaneously accounts for quantum entanglement and relativity's two postulates. PLEASE NOTE MY USE OF THE WORD PHYSICAL IN ALL THE ABOVE. Thanks! I forgot to mention that M-theory papers accomplishing the above would also be of great interest. Thanks!!

 Quote by MistyMountain ...so again I ask...
One request: when you are banned from PF, that in your next reincarnation you post on the Independent Research Forum rather than here.

 Quote by charlesa Misty, I think you are angry and you have every right to be. It is a frustrating time for physics. There has been very little progress recently. However I think your frustration isn't helping. Kea pointed out that the concept was mathematical, and you seemed to take this as a personal insult. Ask someone you like to read your response and explain why it was aggressive, if it didn't seem so to you. As for the mathematical versus physical debate, this goes back to the work of James Clerk Maxwell. Faraday was mocked for his physical explanations, but Maxwell and Faraday were good friends and Maxwell thought in terms of physical models, but managed to express his ideas in terms of mathematics. Newton admitted he had no idea what gravity actually was. The gist seems to be that physical models are rooted in our real world experience, and help individual thinkers, but mathematical models can transcend the limitations of our physical experiences and intuitions. Have hope though - a pile of experimental evidence is building up - especially in the field of cosmology - that undermines current orthodoxy. This evidence will reach critical mass - and physics will have another golden age. Stay calm - don't take yourself too seriously - and you could be part of this golden age..

Newton's mathematical models never transcended the physical reality of gravity.

They described it.

Mathematics should not be seen as a wildcard to get millions from NSF in the form of physics funding, while never having to perform physics.

And that is why I am looking for papers on String Theory, or LQG, that:

1) model a fundamental physical reality from which both quantum mechanics and relativity descend.

2) offer a simple postulate which accounts for a deeper physical reality from which both quantum mechanics and relativity descend.

3) offer a simple postulate and/or physical model which simultaneously accounts for quantum entanglement and relativity's two postulates.

 Quote by Kea One request: when you are banned from PF, that in your next reincarnation you post on the Independent Research Forum rather than here.

Why would I be banned for

a) trying to get everyone to stay on topic
b) trying to get everyone to talk about physics?
c) trying to find links to any successful papers in the realm of LQG, string theory, and M-theory?

Certainly everyone else here will be banned before me for:
1) deviating from the topic
2) posting links to nonsensical mathematics
3) hurling insults unbecoming of highly-educated men and women

I bring love and joy to this forum.

I bring light, liberty, and the spirit of physics rooted in physical reality.

God bless all my brothers here!

I am setting the stage for the master theory, and I am still tryingto find some good references to string Theory. I wish to give my brothers (and sisters) credit where credit is due.

Mentor
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 Quote by MistyMountain I can hardly wait to post my theory here, but first I need a guarantee that it will be examined in the context of physics, and not in some arbitrary kangaroo court manned by NSF funded hacks, kool-aid addicts, and people with axes to grind. I know it's after Christmas, and nobdoy owes me nuthin', but I still believe in Santa Clause, so again I ask: I am looking for papers on String Theory, or LQG, that: 1) model a fundamental physical reality from which both quantum mechanics and relativity descend. 2) offer a simple postulate which accounts for a deeper physical reality from which both quantum mechanics and relativity descend. 3) offer a simple postulate and/or physical model which simultaneously accounts for quantum entanglement and relativity's two postulates.
Time to put up or shut up. Submit your theory to the IR forum; if it meets the guidelines, then we can all discuss it.

Until then, do not keep posting the same question. (This is considered spamming and trolling.) Locked.