Re: membrane causality

Posted by paultrr on September 04, 2003 at 13:49:58:

In Reply to: Re: membrane causality posted by sol on September 04, 2003 at 11:16:13:

Even String Theorists have been admitting for a while that Strings are composed of something themselves. That something, using the wording here is bits of fabric all woven into the String. In general the actual particle state exists from the String scale itself on up, while the fabric scale, again using this example, is more actually what forms the String that forms the particle.

However, going back to textiles as an example strings can have all different qualities and those qualities are determined by the type of fabric or material they are woven from. So in essence if you want to know why one String is a specific way you have to look at what it is composed of and how it was composed. Geometry determines everything about the structure of space-time even down at scales below that of the String.

String theory used to be a theory of strings. string theorists state that the fundamental principle of string theory was that the things we think of as particles are in reality extended objects that look like closed vibrating loops of string.

In addition to strings, M-theory contains a zoo of higher dimensional objects; e.g. 2-dimensional membranes (aka 2-branes), 3-dimensional `3-branes', etc. An object with p spatial dimensions is known as a p-brane. These branes are now thought to be as fundamental as the string itself. The various branes are related to fundamental strings by powerful symmetries known as dualities.

The branes can form up into Strings and Strings can also form up into branes, but both objects are composed of something more primary themselves. Take String and one can weave a fabric which well term a brane or sheet. Yet, that same sheet can be decomposed into its basic string which in turn can be decomposed into its basic fabric parts itself.

Then we come to P-Branes which are far more complicated objects than are strings.

The most shocking outgrowth of the physics of branes has been the Maldacena conjecture. This conjecture states that M-theory subject to particular boundary conditions is in fact equivalent to some supersymmetric Yang-Mills theory on a manifold of smaller dimension. One example is the so-called AdS/CFT correspondence, in which string theory with boundary conditions matching the ten-dimensional manifold given by the product of 4+1 Anti-DeSitter space and a five-sphere (AdSsub5 x S^5) is conjectured to be equivalent to 3+1-dimensional super Yang-Mills theory.

The concepts involved in LQFT simply discribe what makes up these small structures themselves and in essence discribe how the String, that is the particle as an extended object, is formed.

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Follow Ups: (Reload page to see most recent)

• Membrane causality as shown with a balloon -- pelastration 9/05/03 (1)
  • Re: Membrane causality as shown with a balloon -- paultrr 9/05/03 (0)

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