Help regarding strings and m-theory

[aekanshchumber]

To everyone,

Being new to string theory (m-theory) this theory is not completely clear to me. I'd be like if some one please help me in understanding it.

Thanks Aekansh

 

[sol2]

To everyone,

Being new to string theory (m-theory) this theory is not completely clear to me. I'd be like if some one please help me in understanding it.

Thanks Aekansh

Hope this helps, as I am sure it will. Kaku is very heplful as well. Some do not appreciate this link?

Superstring theory is an attempt to explain all of the particles and fundamental forces of nature in one theory by modeling them as vibrations of tiny supersymmetric strings. It is considered one of the most promising candidate theories of quantum gravity. Superstring theory is a shorthand for "supersymmetric string theory" because unlike bosonic string theory, it is the version of string theory that incorporates fermions and supersymmetry.

At present, the deepest problem in theoretical physics is harmonizing the theory of general relativity, which describes gravitation and applies to large-scale structures (stars, planets, galaxies), with quantum mechanics which describes the other three fundamental forces acting on the microscopic scale.

http://en.wikipedia.org/wiki/Superstrings

Thanks to its contributors---we have many links here that answer lots of your questions

Brane Cosmology

Some questions are disquieting because they can be answered in only one of two equally mind-boggling ways. For instance, are we the sole intelligent beings in the universe, or will we find others? Another discomforting doozy is this: did the universe begin at some remote time in the past, or was it always here?

http://www.sciam.com/article.cfm?articleID=000C55B5-C29B-1CDA-B4A8809EC588EEDF&pageNumber=1&catID=4

 

[Tom McCurdy]

www.quantumninja.com/toe

is a site that I am trying to work on building to help people first starting studying string theory, please tell me in what areas you would like to know more information about.

 

[PRodQuanta]

aekanshchumbersaid:I'd be like if some one please help me in understanding it.

You will find, and everybody will probably agree, that all of us at PF are asking that same question.

Paden Roder

 

[Tom McCurdy]

Well ask a specific Question and let's see what we can do

or just read elegant universe

 

[aekanshchumber]

how did the idea of 11 dimension universe came?what made the theorist tothink that the universe might exist in 11 dimensions. it could be more or less. and what does these extra dimensions tell or represent like 3-dimenssional spce let us move.
thanks

 

[sol2]

If this is a expansitory mode, from where did it originate?

Here is (x,y,z,t)+six=Ten The Bubble encapsulating all of it, is eleven? M stands for Membrane.

From a one dimensional string, how would we get there? I had been looking for geometrical consistancy, so looking at model constructions, how does a sphere originate?

If from a point, where is this? If the gravitational collapse takes place in the black hole, we quickly come to recognzie where this point would emerge from becuase as this black hole collapses, tremendous heat is generated, and at Planck length energy s looked at quite differently. Expansitory modes must orignate from some place.

So particle reductionism has been applied to energy considerations. They had no choice. They have run out of room(energy) and needed a different place to look at this. So cosmologically we understand then how particle reductionism has now changed our view of the cosmo?

Algebraic Topology - Sol Feb 23, 2004 04:51 pm
Posted by sol on June 16, 2003 at 07:40:58:

In quantum physics, there is a measurement known as the Planck Scale (10^-35 meters). This is, to make it short, the tiniest space which any object can fill before it becomes pure energy.

At this scale, something strange happens to the laws of physics. Instead of just disappearing into oblivion, objects at this scale become multidimensional strings which represent all the properties of the object...

If R is very small, then the masses of these Kaluza-Klein modes are very large even when n is small. So that means we'd need very high energy to create these particles in an accelerator experiment. If R is very large, then the Kaluza-Klein modes starts to form a continuous spectrum.

http://superstringtheory.com/experm/exper5a.html

 

[Tom McCurdy]

why 11 dimensions

how did the idea of 11 dimension universe came?what made the theorist tothink that the universe might exist in 11 dimensions. it could be more or less. and what does these extra dimensions tell or represent like 3-dimenssional spce let us move.
thanks

http://www-th.phys.rug.nl/~schaar/htmlreport/node12.html

Well added dimensions wasn't something completely unique to string theory it actually started with Kaluza Klein theory in 1919 which postulated the existence of an extra spatial dimension that was currled up. You see mathmatically you have a lot more freedom than you do in what you view as reality. For example let's say you calculate the volume of a 4-d object, it would simply be $$length1 * length2 * length 3 * length4 = volume$$ So dimensions were added because it allows more freedom mathmatically and allowed the physicsts do do additonal calculations to unify EM with GR. It went from there to 10 dimensions with string theory. The strings needed the extra degrees of freedom to viberate. Since the particular viberation of a string determines what properties it has it needed to be able to viberate in more than just 3 extended dimensions, so again mathmatically they added the dimensions. (here is a good link on history of dimensions in relation to string theory http://www.pbs.org/wgbh/nova/elegant/dimensions.html )

Now if you get why there needs to be extra dimensions (to allow for more freedom for strings) it becomes apparent that the extra dimensions must be in very specific shapes to get particular viberations. This is where the term calabi yau manifold comes from. It is the predicted shape of the curled up dimensions. However there are thousands of calabi yau shapes so they must be limited down further based on how they would create viberations. And I believe currently we need a calabi yau manifold with 3 holes which allows for the extended dimensions we are familar with today.

However the 10 dimensional model of string theory caused a problem for most people becaue it produced 5 different string theories which a man named Ed Witten was able to combine into one theory known as M-theory which basically said the old theories were merely reflections of each other. (Also keep in mind string theory math is approximate at this stage which is why they added a dimension when they learned it needed an extra one)

So they basically came up with the idea for extra dimensions by mathmatically recoginzeing what they could do with extra dimensions in accordance with a particular theory.

 

[sol2]

good explanation Tom


With this link here, we will understand better what was being relayed in post above Tom's.

 

[Tom McCurdy]

thanks sol

 

[aekanshchumber]

Thanks to all of you for the posts,
But i still can not understand that how did the basic four forces are told as the ripples in the higher dimensions. once, i read an article by Michio Kaku in which he said that the forces are the ripples in the higher dimensions which we can't see but feel that they are there.

Awaiting replies
Aekansh

 

[sol2]

Thanks to all of you for the posts,
But i still can not understand that how did the basic four forces are told as the ripples in the higher dimensions. once, i read an article by Michio Kaku in which he said that the forces are the ripples in the higher dimensions which we can't see but feel that they are there.

Awaiting replies
Aekansh

Hyperspace, by Michio Kaku Pg 9

Since the theory was considered to be a wild speculation, it was never taught in graduate school; so young physicists are left to discover it quite by accident in their casual readings. This alternative theory gave the simplest explanation of light; that it was really a vibration of the fifth dimension, or what used to be called the fourth dimension by the mystics. If light could travel through a vacuum, it was because the vacuum itself was vibrating, because the “vacuum” really existed in four dimensions of space and one of time. By adding the fifth dimension, the force of gravity and light could be unified in a startlingly simple way...

What is the true Vacuum?

https://www.physicsforums.com/showpost.php?p=298300&postcount=12

 

[aekanshchumber]

I think i have started learning a little bit about it. Recently i read a book in which these things were explained. But now a new problem arrived Hiegher dimensional mathematics.In the book it was said that when the basic laws of nature are tried to solve in hiegher dimensions the are much simplified. Like a tiger in its natural habitat but in our three dimensional world these forces are little it destorted like the tiger in capitivity.
Now will anybody please tell me some thing about the Hiegher Dimensional mathematics.

Thanks