String theory and Loop Quantum theory combined?

[JonathanSchmold]

This is a big ramble fest I had with myself considering Loop Quantum gravity and M-Theory and I was wondering if anyone can either clarify my thoughts or clearly explain to me the difference on why they can't work together... here is my picture of my large conversation with myself on facebook and I doubt anyone on facebook has the IQ to solve this and the picture is in the attachments... please help me (in order to open it, save it to your desktop, and then press preview and scroll up or down to see the size)

Edited June 26, 2010 by JonathanSchmold
explaining instructions

[JonathanSchmold]

K? No replies yet?

[insane_alien]

perhaps if you post it here instead of making us read an image of face book that approximates a wall of text to the point of be ing unreadable.

[ajb]

It was once thought that it could be the case that both string theory and loop quantum gravity were just different realisations of some larger theory. They do share some very similar conclusions when asked questions they can both tackle. For instance both give an understanding into the statistical mechanics of black holes and both suggest modification of our notion of space-time near the Planck scale.

 

As far as I know, the ideas that strings and loops are related has not be realised. For sure, not many people work on both areas. Maybe a literature search will help.

 

See what you can find on http://www.arXiv.org

 

Hope you get some insight into your questions.

[JonathanSchmold]

So my rambling could neither be proved right now, or proven wrong, but just tested instead? It would make sense though in my argument where everything has its place in the universe or as I called it a "niche"... why can't it work?

[ajb]

So my rambling could neither be proved right now, or proven wrong, but just tested instead?

 

Well, your ramblings are just that. It is nice that you are interested, but it will require a lot of mathematical competence to ask the right questions to investigate the potential similarities.

 

Good luck with your ideas.

[JonathanSchmold]

I am only 14 and are more interested in computers than anything so yeahh... I still don't understand why the 2 wont work because loop quantum gravity is where everything in the universe is a network (a larger scale explanation of everything) while M-Theory focuses on the minute scale things inside of quasars, or the "binary" of all substances... Why are there so much arguments as to which one is right or wrong but not both correct??

[ajb]

Why are there so much arguments as to which one is right or wrong but not both correct??

 

Both have very different gaols. String theory from the start was a way of thinking about particle physics, it was later realised that it necessarily contains gravity. After that string theory was a potential unification scheme.

 

Loop quantum gravity is an approach to quantize gravity, in the form of Einstein's general relativity written in a "non-standard" (lets say non-traditional) way. It's ambitions are more modest than string theory.

 

As string theory makes predictions about the nature of all matter it is, in my opinion more likely to make contact with experiment than loop quantum gravity. For instance, finding supersymmetry at the LHC will be seen as supporting evidence that our ideas on string theory are along the right lines.

 

I think that the biggest problem with the politics here is that very few people understand both strings and loops. Personally, I know much more about strings, not that I work in string theory directly.

[JonathanSchmold]

and comes the fact that it is not PROVEN that one is wrong because very few qualified people actually study both, but your argument does not either interfere with mine or go with it... and LQG is still a network and string theory is particles with gravity (as you stated)

[ajb]

and comes the fact that it is not PROVEN that one is wrong because very few qualified people actually study both...

 

Both could be acceptable, or neither could be.

 

but your argument does not either interfere with mine or go with it...

 

Not that I know what your argument is...

 

However, having few people fluent in both frameworks means that it is not going to be well-know how, or even if at all various constructions and calculation in either relate to the other.

 

and LQG is still a network and string theory is particles with gravity (as you stated)

 

Ok, loop quantum gravity uses spin networks. Do you mean something else by "network"?

[JonathanSchmold]

YES but all the strings in string theory can contribute the the spin network as shown http://en.wikipedia.org/wiki/Spin_network <-- here in the diagram but for each of the numbers there could very well be a sub-atomic particle, then quarks, then quasars, and inside of that are the strings in string theory... My argument is basically that I don't know why people are fighting about which is right or wrong but possibly both could meld together making a different theory that is correct, but neutral in the same way without violating any laws of physics

Edited June 27, 2010 by JonathanSchmold
needed more detail

[ajb]

YES but all the strings in string theory can contribute the the spin network as shown http://en.wikipedia.org/wiki/Spin_network <-- here in the diagram but for each of the numbers there could very well be a substance, and inside of that are the strings in string theory...

 

This I don't understand. The wikipedia article does not tell me anything about going from strings to spin networks.

 

There are string networks, Ashoke Sen wrote a paper about these. As far as I know, it is not understood how these relate to spin networks and loop quantum gravity. (I imagine one would need a supersymmetric formulation of LQG) But I could be wrong.

[JonathanSchmold]

You said that LQG relates to spin networks and thats what that is! Lol but still... it is explained in that article that it explains how subatomic particles react with eachother but string theory would explain what is inside of them

[Bignose]

I think that you are possibly confusing everyday arguing with scientific arguing.

 

Scientifically (and I hope ajb will fix anything I get wrong), both ideas are really still in some preliminary stages. That is, there has been very few experiments that directly support or negate the ideas. So, at this time, both ideas can only be explored mathematically and attempt to discover if the logical consequences of either end up making predictions that are against experiments that have been done. That is, it takes a lot of time and money and creativity to be able to make experiments that test the theories directly, and they just haven't been done yet. So, all that can be done is to make sure that the theories don't predict things that we know are wrong today.

 

Scientifically, no one is saying that they can't be joined together, but if not many people are experts in both of the areas, there just may not enough interest to attempt that. Mathematically, exploring the implications of one or the other are complicated enough and certainly aren't easy to get to. I can easily see how people probably aren't satisfied that either one is explored enough yet that attempting to combine them may only complicate things needlessly and unhelpfully.

 

By analogy, if you don't know to solve algebraic equations, attempting to throw some trigonometry into a problem and mix them together would really only muddle things up. You want to master algebra, and then master trigonometry, and then do problems involving both. Right now, they are trying to get each one nailed down separately, and then they will see if they may be common in some area.

 

There may be some arguing from people not in the scientific community, that is almost wholly based on opinions and popularizations of the science. It is hard to argue about it unless you know the mathematics behind the idea. And, I am sure that there are disagreements about somethings in the scientific community. I have no idea if it is true or not, but at one time there seemed to be 5 different flavors of string theory that all seemed possible (i.e. not conflicting with current state knowledge). I am sure that people working on the problem each have their own preferences or intuition about which is right.

 

But, in the end, experimentation will determine which flavor of the idea is most correct, not arguments. And that is the great thing about science. The scientists may have their individual opinions, but they all are waiting to see what the experiments say.

[JonathanSchmold]

Ahh so I am questioning things that very well may not be able to be proven due to our lack of technology?

[ajb]

You said that LQG relates to spin networks and thats what that is!

 

Right, part of the framework of loop quantum gravity are spin networks. You write gravity in terms of the Ashtekar variables and then use Wilson loops as a set up for nonperturbative quantum gravity. In a sense, the spin network is a generalisation of the Wilson loops.

 

The reformulation in terms of Ashtekar variables basically turns gravity in to two copies of [math]SU(2)[/math] gauge theory.

 

So, unless I am mistaken the spin networks here are directly related to the irreducible representations of [math]SU(2)[/math]. Rather than more general compact Lie groups.

 

Also, the interpretation of all this is not the same as Penrose's original work.

 

Lol but still... it is explained in that article that it explains how subatomic particles react with eachother but string theory would explain what is inside of them

 

I don't think the wikipedia article does that.

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Ahh so I am questioning things that very well may not be able to be proven due to our lack of technology?

 

Both mathematical technology to understand if string theory and LQG really are the "same thing" and the practical technology to test many of the ideas of quantum gravity in general.

 

Cosmology and them maybe astrophysics, I feel are the best places to think about tests of quantum gravity.

[JonathanSchmold]

I don't think the wikipedia article does that.

 

Actually yes it does! It is explained here "In physics, a spin network is a type of diagram which can be used to represent states and interactions between particles and fields in quantum mechanics" and under quantum mechanics "Quantum mechanics (QM) or Quantum Physics, is a branch of physics describing much of the behavior of energy and matter at the atomic and subatomic scales" So my argument still proves valid

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Key words meaning behaviour of energy and MATTER at the atomic and sub atomic level... beyond the subatomic level is quarks then quasars and inside those are the strings in the string theory which can be contributed to the spin network AND OMG MY HEAD HURTS

Edited June 27, 2010 by JonathanSchmold
Consecutive posts merged.

[ajb]

I don't think I know enough about loop quantum gravity to say a lot more than I have.

 

The book by Smolin I enjoyed, Three Roads to Quantum Gravity. It is a popular(ish) science book rather than a monograph of quantum gravity. In it Smolin suggests that string theory and quantum gravity are somehow "the same thing". However, I don't recall any solid mathematical argument how or why. Philosophically, both approaches require us to use 1-d objects strings or loop. However, today we know that higher dimensional objects, the branes play a equal role in string theory as the strings. Maybe Smolin's string <-> loop "correspondence" is not really there.

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Actually yes it does! It is explained here "In physics, a spin network is a type of diagram which can be used to represent states and interactions between particles and fields in quantum mechanics" and under quantum mechanics "Quantum mechanics (QM) or Quantum Physics, is a branch of physics describing much of the behavior of energy and matter at the atomic and subatomic scales" So my argument still proves valid..

 

I think that is talking about Penrose's original work and application of spin networks. I think this is different to the interpretation used in LQG. Unless, you want to think of the graviton as a "space-time phonon" maybe.

[JonathanSchmold]

Can someone link this to a university that can help me resolve this problem and IF I AM LUCKY revolutionize physics? Because I don't know if this can be solved on a mediocre (I mean't something such as un-professional) science forum, but only through actual tests... Would this be able to be proposed to someone who works in advanced physics?

Edited June 27, 2010 by JonathanSchmold
I wanted to clarify something

[ajb]

Can someone link this to a university that can help me resolve this problem and IF I AM LUCKY revolutionize physics? Because I don't know if this can be solved on a mediocre science forum, but only through actual tests... Would this be able to be proposed to someone who works in advanced physics?

 

Unless you have something truly insightful to say, I doubt any working professor is going to be very interested. Couple this with the fact very few people know both approaches well enough to attempt a "unification".

 

You question about if the two can be united is a good one. It has been proposed before with no real "correspondence" found.

 

As an aside, there is little point trying to be rude about this forum or its users.

 

Good luck with it all.

[JonathanSchmold]

Unless you have something truly insightful to say, I doubt any working professor is going to be very interested. Couple this with the fact very few people know both approaches well enough to attempt a "unification".

 

You question about if the two can be united is a good one. It has been proposed before with no real "correspondence" found.

 

As an aside, there is little point trying to be rude about this forum or its users.

 

Good luck with it all.

 

I mean't no offense to the forum but a more professional approach to the question will probably prove more effective

[ajb]

I mean't no offense to the forum but a more professional approach to the question will probably prove more effective

 

Sorry, if you think I have not been professional.

 

I do not work in LQG so I am only really able to say what any one in my position should be able to say. Coming from a quantum field theory and string theory "background" what I can say is that I am not aware of any mathematical statements that make it clear if LQG and string theory are related.

 

That is not to say that it is necessarily impossible that they could be united. It would be very nice if this were all made clear.

[JonathanSchmold]

Sorry, if you think I have not been professional.

 

I do not work in LQG so I am only really able to say what any one in my position should be able to say. Coming from a quantum field theory and string theory "background" what I can say is that I am not aware of any mathematical statements that make it clear if LQG and string theory are related.

 

That is not to say that it is necessarily impossible that they could be united. It would be very nice if this were all made clear.

 

Considering the fact that most civilizations did not feel the need for math but somehow advanced? I think this is especially proven in the means of the development of the first battery because it was not needed to make the first battery but merely needed previous knowledge of chemicals in order to join cells together and make the worlds first battery so whos to say that math is one hundred percent necessary in this case? And if you search up LQG it actually kinda sounds like it could be melded as something on a larger scale than M-Theory right?

[ajb]

Considering the fact that most civilizations did not feel the need for math but somehow advanced? I think this is especially proven in the means of the development of the first battery because it was not needed to make the first battery but merely needed previous knowledge of chemicals in order to join cells together and make the worlds first battery so whos to say that math is one hundred percent necessary in this case?

 

You are saying that one can do theoretical physics without mathematics?

 

 

And if you search up LQG it actually kinda sounds like it could be melded as something on a larger scale than M-Theory right?

 

There is an industry devoted to LQG cosmology. Also, there is an industry devoted to stringy/M-theory cosmology.

[JonathanSchmold]

You are saying that one can do theoretical physics without mathematics?

 

 

 

 

There is an industry devoted to LQG cosmology. Also, there is an industry devoted to stringy/M-theory cosmology.

 

Considering that it is only PROVEN through math, it is necessary but to try to do tests one may only need the knowledge of how it works but not at a mathematical level, but if one were to apply these to actual technology, math would DEFINATELY be necessary