M-Theory

[pyroglycerine]

Hi,

 

I watched a BBC documentary recently about the string theory, super-gravity theory, and the big bang theory.

The conclusion was, in short, that the generally accepted theory at present is there are 11 dimensions (ten spacial that make up an interconnected membrane of matter, and the other time) in our universe and the big bang was the result of the rippling membranes of two other universes colliding.

The documentary was quite old. I'm just wondering, is this still the generally accepted theory? Have there been any developments in the theory since that documentary was made?

The name theory was M-Theory and the name of one of the major contributors to the thoery was Neil Turok

 

pyroglycerine

[ajb]

Have there been any developments in the theory since that documentary was made?

When was the documentary made?

 

It may have missed the Bagger–Lambert–Gustavsson action (though this is technical and maybe not for such a TV program). Anyway, the hope is that this action or something like it will provide a microscopic description of (stacks of) M2 and M5 branes. I don't think this was really realised and the mathematical structures required are have very few examples.

[pyroglycerine]

When was the documentary made？

Presumably in the late 1990's - early 2000's

[ajb]

Presumably in the late 1990's - early 2000's

So it may also have not said much about the string landscape?

[pyroglycerine]

It was quite vague to be honest, I guess so the wider audience can understand. They talked about the string theory that matter exists in strings of which are all interconnected in 10 spacial dimensions which forms a membrane that is our universe. They didn't go into much detail, which is frustrating because it made it very hard to picture. If thats what you meant by the string landscape then no, they didnt say much about it.

 

I would like to learn more though, its very intersting.. Any suggested reading?

 

Also, they claimed the singularity problem of what caused the big bang was solved - it was caused by two universes colliding. But surely that's a paradox because then what created those universes. You cant just solve the problem by saying that there is an infinite number of universes which all created each other!

[ajb]

If thats what you meant by the string landscape then no, they didnt say much about it.

The string landscape is the collection of all the false vacua of string theory. The number of these vacua is huge, estimated to be 10^500. The choices here are to do with the number of possible string compactifications you can have, which are related to the possible Calabi–Yau manifolds you use and the fluxes etc.

 

It is thought that one of these vacua contains the physics of our Universe.

 

I would like to learn more though, its very intersting.. Any suggested reading?

Start with Wikipedia.

 

Also, they claimed the singularity problem of what caused the big bang was solved - it was caused by two universes colliding.

This sounds like the ekpyrotic universe.

 

The idea is that two branes that are floating about in the bulk collide and this is what we see as the big bang. The model quickly settles down to the Lambda CDM model on one of the branes and so it seems not to be at odds with our current understanding of cosmology.

[pyroglycerine]

Thanks!

[Schneibster]

ajb, pretty sure this one predates the Landscape. I think the documentary's talking just about straight M theory, and cut it very short; perhaps they didn't even talk about what the string theories are that make the parts of it we've figured out up, just did a handwave like many such programs do, and went on to the ekpyrotic hypothesis which was what they really wanted to talk about. (And of course, you're absolutely correct, it is, in fact, the ekpyrotic hypothesis they're talking about. I have the impression it's the main part of the theory.)

 

pyroglycerine, ajb is too modern for your documentary; he knows too much! Your program covered a very narrow piece of current cosmology, a hypothesis that has been put forward by a small faction. However, there is some evidence to indicate that they may be correct, but only looking at things from one very narrow perspective; their idea is likely to actually be one among many explanations, all correct, just as (for example) both the field and particle descriptions of elementary physics are two facets of the same truth.

 

Just at the moment, however, cosmology has looked away from this hypothesis and is looking at data that is emerging from the Sloan Digital Sky Survey, in a program called "BOSS." I suspect we'll see the ekpyrotic hypothesis again, but at this point most cosmologists and astrophysicists are looking at this emerging data source since it is pretty much fountaining new data forth. Oooohhhh, shiny.

Edited April 9, 2014 by Schneibster

[pyroglycerine]

Thanks Schneibster.

I think if I want to learn about it properly and gain a thorough understanding I'll have to start by learning the fundamentals of theoretical physics and cosmology.

It seems far to complex a subject to dive in at the deep end so to speak, hence why the program left me confused.

Apart from wikipedia, can you suggest any good reading? Is Stephen Hawking's 'A brief history of time' a good place to start? (Bear in mind this is for leisure, I have my Chemistry degree to focus on at the moment)

[Schneibster]

On ekpyrotic theory? No, no books.

 

On physics, if you're working on a chemistry degree you're already getting a lot. I think the two best-known Brian Greene books are your best bet if you don't want to take on the heavy-duty math of string physics. (The Elegant Universe and The Fabric of the Cosmos.) This will give you the operating principles, and let you choose where you need to delve deeper.

 

If you need to beef up on the real basics, try The Force of Symmetry by Vincent Icke. No string theory in that, though; OTOH, a darn good overview of everything short of it, from a not-so-much-math perspective that won't strain your brain when you're taking a break from cramming for a mid-term. It's quantum and relativity physics for liberal arts majors. You won't be able to drive the locomotive but you'll know where all the important knobs, buttons, levers, and control wheels are.

Edited April 9, 2014 by Schneibster

[Lizzie L]

Apart from wikipedia, can you suggest any good reading? Is Stephen Hawking's 'A brief history of time' a good place to start? (Bear in mind this is for leisure, I have my Chemistry degree to focus on at the moment)

 

 

I enjoyed Endless Universe: Beyond the Big Bang by Turok and Steinhardt themselves. I found it remarkably accessible!

[Intellectual]

I think World Science U is a good place to go to learn about physics