Guys,
Physicists all over the world r thinking that superstring theory is theory of everything. So lets Discuss it .
Physicists all over the world r thinking that superstring theory is theory of everything. So lets Discuss it .
Superstring Theory
The only problem I have with it are all the extra dimensions that are folded in on themselves. I don't have any problem with extra dimensions, but my definition (possibly faulty, I'll admit) holds that a dimension should be infinite.
The four I can perceive certainly are...
The four I can perceive certainly are...
| ocalhoun wrote: |
| The only problem I have with it are all the extra dimensions that are folded in on themselves. I don't have any problem with extra dimensions, but my definition (possibly faulty, I'll admit) holds that a dimension should be infinite.
The four I can perceive certainly are... |
Oh yeah? Prove it. ^_^
There are two problems with your objections:
1.) Dimensions don't need to be infinite.
2.) Folded dimensions aren't necessarily finite.
| Indi wrote: |
|
1.) Dimensions don't need to be infinite. 2.) Folded dimensions aren't necessarily finite. |
1) Why?
2) Please Explain.
Yeah, the only reason it appears string theory isn't the theory of everything yet is that it's not verifiable by experimental results. Until someone really clever comes along and figures out a way to check out all those extra dimensions from our little 3/4-D vista, it sounds like whale music to me.
| charlieg wrote: |
| Yeah, the only reason it appears string theory isn't the theory of everything yet is that it's not verifiable by experimental results. Until someone really clever comes along and figures out a way to check out all those extra dimensions from our little 3/4-D vista, it sounds like whale music to me. |
There's an excellent little book, only about 80 pages, called Flatland, A Romance of Many Dimensions by Edwin A. Abbott. It describes in about the most simplist manner the differences between dimensions and our problems in perceiving them. It's a quick read if your interested.
Dear charleig, next year november the 'LARGE HADRON COLLIDER' is going 2 switch on at CERN. LHC the world's greatest particle accelerator. Here the proton will smash each other at alsmost the speed of light. So physicists believe firmly, here new particles will be created,which moves through the extra dimention.So extra dimentions will be proved.
| Physicist wrote: |
| Guys,
Physicists all over the world r thinking that superstring theory is theory of everything. So lets Discuss it . |
By all means. Are you familiar with the basics ? Do you know what Calabi-Yau space is ? Have you heard of Kaluza-Klein compactification ?
Chris.
Here is an on-line lecture on string theory:
http://www.newton.cam.ac.uk/webseminars/mondays/2002/05/20/dijkgraaf/
Regards
Chris
http://www.newton.cam.ac.uk/webseminars/mondays/2002/05/20/dijkgraaf/
Regards
Chris
Guys,
can u tell how many days i hv 2 wait 2 get domein?
48 hrs passed..Oh..
can u tell how many days i hv 2 wait 2 get domein?
48 hrs passed..Oh..
| Physicist wrote: |
| Guys,
can u tell how many days i hv 2 wait 2 get domein? 48 hrs passed..Oh.. |
A few days - I guess it depends on how busy the hosts are....
Chris
| ocalhoun wrote: | ||
1) Why? 2) Please Explain. |
1.) Because if the "space" the dimensions are in is not infinite, then the dimension can't be infinite (and "space" refers to the dimension space, which may include time). If the space you're interested in is just the room you're in, the dimensions in that space only extend to the boundaries of that room. Many mathematical problems produce solution sets that are closed (bounded), finite spaces. The dimensions of those spaces are thus finite.
In the real universe, the physical universe, if the universe is not infinite, then no dimension in it can be infinite. So far, whether or not the universe is finite is an open question.
2.) A folded dimension could be folded back on itself, forming a circle, which is a line without a beginning or an end - ie, an infinite dimension. You could move forever in that dimension and never come to an end.
But even if that's not the case, the idea of a compactified dimension does not really require that the dimension is finite at all. All it requires is that any motion along the compactified dimension results in a zero displacement. Imagine an infinite line representing your compactified dimension, but in order to move even one micrometer along the dimension requires more energy than exists in the entire universe. Thus most motions along that dimension are functionally 0. So you have an infinite dimension that's macroscopically compactified.
Here's a way to picture a finite universe within an unbounded space which I quite like.
Begin with a Spherical Wave which travels outward from an initial Center. When the Wave encounters other Wave-Centers in the universe then its Wave effectively becomes part of the In-Waves of these other Wave-Centers. Conversely, when the Out-Waves of these other Wave-Centers in Space flow into the initial Wave-Center they effectively become part of its In-Waves. Effectively the Out-Waves have combined to form a Huygens’ combination wave front which forms the Spherical In-Wave of our Wave-Centers.
(taken from http://www.spaceandmotion.com/cosmology-wsm-summary-infinite-space.htm)
Regards
Chris
Begin with a Spherical Wave which travels outward from an initial Center. When the Wave encounters other Wave-Centers in the universe then its Wave effectively becomes part of the In-Waves of these other Wave-Centers. Conversely, when the Out-Waves of these other Wave-Centers in Space flow into the initial Wave-Center they effectively become part of its In-Waves. Effectively the Out-Waves have combined to form a Huygens’ combination wave front which forms the Spherical In-Wave of our Wave-Centers.
| Quote: |
| This Huygens' sharing of waves means that once you go out past a certain distance in Space (the size of our finite spherical universe) then you can no longer count the Out-Waves of this further distant matter as direct contributors to our In-Waves, because these waves have already become part of closer Wave-Center's In and Out-Waves and thus have already been counted as contributing to our In-Waves. This sharing of waves is a profound discovery (Wolff, 1994) as it leads to the solution of the connection between the Infinite and the Finite, and correctly explains the cause of the redshift with distance. Briefly stated (as this is discussed a little later) this explains how we can have a finite Wave-Amplitude/Density (and thus a finite mass and energy for matter) within a finite spherical universe, and yet also be part of an infinite perpetual system of Waves in Space. |
(taken from http://www.spaceandmotion.com/cosmology-wsm-summary-infinite-space.htm)
Regards
Chris
well, i guess this will help you:
Our physical space is observed to have only four large dimensions, and a physical theory must take this into account, but nothing prevents a theory from involving more than 4 dimensions, per se. In the case of string theory, consistency requires spacetime to have 10, 11 or 26 dimensions. The conflict between observation and theory is resolved by making the unobserved dimensions compact dimensions.
Our minds have difficulty visualizing higher dimensions because we can only move in three spatial dimensions. Even then, we only see in 2+1 dimensions; vision in 3 dimensions would allow one to see all sides (including the inside) of an object simultaneously. One way of dealing with this limitation is not to try to visualize higher dimensions at all, but just to think of them as extra numbers in the equations that describe the way the world works. This opens the question of whether these 'extra numbers' can be investigated directly in any experiment (which must show different results in 1, 2, or 2+1 dimensions to a human scientist). This, in turn, raises the question of whether models that rely on such abstract modelling (and potentially impossibly huge experimental apparatus) can be considered 'scientific'. 6-dimensional Calabi-Yau shapes can account for the additional dimensions required by superstring theory.
Calabi-Yau:
Superstring theory is not the first theory to propose extra spatial dimensions; see Kaluza-Klein theory. Modern string theory relies on the mathematics of folds, knots, and topology, which was largely developed after Kaluza and Klein, and has made physical theories relying on extra dimensions much more credible.
There are a lot more theories namely:
1. Bosonic Theory
2. M-Theory
and many more........too much to go into detail. well, i hope you got the gist of it, because nobody can understand all the theories and stuff without doing some research on it. i have been researching on space for the past 1 year, and i feel that i BARELY know anything about it!!!
Our physical space is observed to have only four large dimensions, and a physical theory must take this into account, but nothing prevents a theory from involving more than 4 dimensions, per se. In the case of string theory, consistency requires spacetime to have 10, 11 or 26 dimensions. The conflict between observation and theory is resolved by making the unobserved dimensions compact dimensions.
Our minds have difficulty visualizing higher dimensions because we can only move in three spatial dimensions. Even then, we only see in 2+1 dimensions; vision in 3 dimensions would allow one to see all sides (including the inside) of an object simultaneously. One way of dealing with this limitation is not to try to visualize higher dimensions at all, but just to think of them as extra numbers in the equations that describe the way the world works. This opens the question of whether these 'extra numbers' can be investigated directly in any experiment (which must show different results in 1, 2, or 2+1 dimensions to a human scientist). This, in turn, raises the question of whether models that rely on such abstract modelling (and potentially impossibly huge experimental apparatus) can be considered 'scientific'. 6-dimensional Calabi-Yau shapes can account for the additional dimensions required by superstring theory.
Calabi-Yau:
Superstring theory is not the first theory to propose extra spatial dimensions; see Kaluza-Klein theory. Modern string theory relies on the mathematics of folds, knots, and topology, which was largely developed after Kaluza and Klein, and has made physical theories relying on extra dimensions much more credible.
There are a lot more theories namely:
1. Bosonic Theory
2. M-Theory
and many more........too much to go into detail. well, i hope you got the gist of it, because nobody can understand all the theories and stuff without doing some research on it. i have been researching on space for the past 1 year, and i feel that i BARELY know anything about it!!!
What's the difference between superstring theory and string/brane theory? Is it something about the strings being 'larger' to involve the whole universe instead of just smaller particles of like earth?
| jharsika wrote: |
| What's the difference between superstring theory and string/brane theory? Is it something about the strings being 'larger' to involve the whole universe instead of just smaller particles of like earth? |
No. String theory(ies) arose from particle phsysics to explain the relationship between mass and spin for certain elementary particles (hadrons). As it happened this didn't really work out, but the theory seemed to answer some important questions with regard to gravity and became known as a theory of quantum gravity.
There are several possible string theory models - 5 in fact. That was a problem since all 5 require different models of elementary particles (all need supersymmetry but in different forms). All 5 theories require 10 dimensions of space. It was found, however, that the introduction of an 11th dimension collapses all the 5 theories down into 1 single theory. This is called M-Theory (or Membrane theory).
Regards
Chris
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