.95
#1
Posted 04 September 2007 - 02:59
For a scientific theory to be valid it must be verified experimentally. Few avenues for such contact with experiment have been claimed. With the construction of the Large Hadron Collider in CERN some scientists hope to produce relevant data. It is generally expected though that any theory of quantum gravity would require much higher energies to probe. Moreover, string theory as it is currently understood has a huge number of possible solutions. Thus it has been claimed by some scientists that string theory may not be falsifiable and may have no predictive power.
Studies of string theory have revealed that it predicts higher-dimensional objects called branes. String theory strongly suggests the existence of ten or eleven (in M-theory) spacetime dimensions, as opposed to the usual four (three spatial and one temporal) used in relativity theory; however the theory can describe universes with four effective (observable) spacetime dimensions by a variety of methods.
An important branch of the field is dealing with a conjectured duality between string theory as a theory of gravity and gauge theory. It is hoped that research in this direction will lead to new insights on quantum chromodynamics, the fundamental theory of strong nuclear force.
String theory is formulated in terms of an action principle, either the Nambu-Goto action or the Polyakov action, which describes how strings move through space and time. Like springs with no external force applied, the strings tend to shrink, thus minimizing their potential energy, but conservation of energy prevents them from disappearing, and instead they oscillate. By applying the ideas of quantum mechanics to strings it is possible to deduce the different vibrational modes of strings, and that each vibrational state appears to be a different particle. The mass of each particle, and the fashion with which it can interact, are determined by the way the string vibrates — the string can vibrate in many different modes, just like a guitar string can produce different notes. The different modes, each corresponding to a different kind of particle, make up the "spectrum" of the theory.
Strings can split and combine, which would appear as particles emitting and absorbing other particles, presumably giving rise to the known interactions between particles.
SHOCKWAVE theory includes both open strings, which have two distinct endpoints, and closed strings, where the endpoints are joined to make a complete loop. The two types of string behave in slightly different ways, yielding two different spectra. For example, in most string theories, one of the closed string modes is the graviton, and one of the open string modes is the photon. Because the two ends of an open string can always meet and connect, forming a closed string, there are no string theories without closed strings.
The earliest string model — the bosonic string, which incorporated only bosons, describes — in low enough energies — a quantum gravity theory, which also includes (if open strings are incorporated as well) gauge fields such as the photon (or, more generally, any Yang-Mills theory). However, this model has problems. Most importantly, the theory has a fundamental instability, believed to result in the decay (at least partially) of space-time itself. Additionally, as the name implies, the spectrum of particles contains only bosons, particles which, like the photon, obey particular rules of behavior. Roughly speaking, bosons are the constituents of radiation, but not of matter, which is made of fermions. Investigating how a string theory may include fermions in its spectrum led to the invention of supersymmetry, a mathematical relation between bosons and fermions. String theories which include fermionic vibrations are now known as superstring theories; several different kinds have been described, but all are now thought to be different limits of M-theory.
While understanding the details of string and superstring theories requires considerable mathematical sophistication, some qualitative properties of quantum strings can be understood in a fairly intuitive fashion. For example, quantum strings have tension, much like regular strings made of twine; this tension is considered a fundamental parameter of the theory. The tension of a quantum string is closely related to its size. Consider a closed loop of string, left to move through space without external forces. Its tension will tend to contract it into a smaller and smaller loop. Classical intuition suggests that it might shrink to a single point, but this would violate Heisenberg's uncertainty principle. The characteristic size of the string loop will be a balance between the tension force, acting to make it small, and the uncertainty effect, which keeps it "stretched". Consequently, the minimum size of a string is related to the string tension.
#2
Posted 04 September 2007 - 03:08
Topic moved for great justice.
#3
Posted 04 September 2007 - 03:16
#4
Posted 04 September 2007 - 03:41
#5
Posted 04 September 2007 - 06:58
#6
Posted 04 September 2007 - 07:01
#7
Posted 04 September 2007 - 09:08
#8
Posted 04 September 2007 - 09:41
The brave hide behind technology. The stupid hide from it. The clever have technology, and hide it.
—The Book of Cataclysm
#9
Posted 04 September 2007 - 09:49
#11
Posted 04 September 2007 - 13:52
#12
Posted 04 September 2007 - 16:00
but i prefer more practical usage of physics
don't click this link...
#13
Posted 04 September 2007 - 16:55
#15
Posted 05 September 2007 - 03:06
now what this has to do with .95 is that the release is a greater connection to the final release that can not touch this release nor can it occupy the close proximity of .93's release..
#16
Posted 05 September 2007 - 09:29
#17
Posted 05 September 2007 - 23:23
Very interesting though. However my brain started hurting and I started forgetting things I have to do this week after about the 4th paragraph so i stopped.
Ill try reading this during a time when Im a bit more "enlightened"
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