[-empyre-] String Theory.....Swan Song?

Akram Khan Akram.Khan at brunel.ac.uk
Tue Nov 1 10:17:00 EST 2011

Dear all, 

this has be a fun month for a scientist to hear such sweet and creative voices, it would be wonderful to meet up or arrange a workshop where we can explore in greater depth the complexity of the interfaces in particular with science! I can not resist but to copy an over i gave on the development of string theory and its the importance of scientific dream in the 21st century......please excuse me for the long email....



It seems that what most distinguishes our species from the rest of creation is our capacity for abstraction...a facility for the symbolic representation of the world in which we find ourselves....this allows us to rise above the stream of our senses and ask questions about the meaning of it all...what are we? Where have we come from? Where might we be going? What & how can we change it at all....these are the questions that’ve been asked by our species since time immemorial...many & varied’ve been the answers reached...but with the turning of the years there’s been an ever insistent desire to transcend the limits of our cultural contexts & our narrow need for narratives that provide consolation in a hostile, indifferent world...& then, some 400 years ago, with the crucial development of the Scientific Method, we had what is now known as the Scientific Revolution, leading to such spectacular successes in our quantitative understanding of the world, on all human scales, that we felt by the end of the 19th century as if Nature had no more to give...& as the great scientists of the age congratulated one & all, on a job well done, there came an almighty storm...& we found in the wreckage left behind that what we’d thought was the holy grail of physics, a ‘Theory of Everything’, was no such thing at all...we’d looked into the mirror of Nature & only seen the universe cut down to our size...& we are so small a part of all there is that what we’d seen was a shocking caricature of reality...& so Modern Physics was born, with quantum mechanics to guide us on our journey over distance scales that take us to the very heart of the atom, & relativity to help us over distance scales that span the cosmos, & with entities that travel at speeds approaching that of light...

The 20th century has been, for fundamental physics, the most exciting yet...opening up hitherto unimaginable regions of the physical...& as our understanding has exponentially increased so has the possibility of a Theory of Everything become a reality again...with an all-inclusive, aesthetically pleasing, mathematically consistent framework incorporating all the basic principles of physical reality, tantalisingly close...
The Standard Model of particle physics offers a detailed understanding of all the forces of Nature but leaves gravity out... it has, also, many parameters that need to be precisely adjusted within certain experimentally measured values, in order to make it a successful predictive model. How is it possible that the final theory of science could be so delicate... &, furthermore,  require one scheme – relativity - for the very large, and another - quantum mechanics – for the very small. 

So some brave souls resurrected an idea that had long been rejected by the mainstream - String Theory. It postulated that particles were not zero-dimensional points, as the Standard Model supposed, but instead were tiny strings whose vibrations are reflected in the observed properties of the fundamental particles. 

Though its possibilities are still being intensively explored, many physicists are coming to believe that String Theory, or one of its derivatives, will ultimately prove to be the long-sought final "Theory of Everything".

The Central Conflict

The incompatibility of relativity and quantum mechanics has been called the "central conflict" of modern theoretical physics. The conflict arises from the quantum chaos generated by the properties of the Uncertainty Principle.  Over regions of space smaller than the Planck length, the quantum chaos becomes manifest, & the smooth "fabric" of spacetime necessary if general relativity is to be applicable becomes disrupted. When attempts are made to merge quantum mechanics and general relativity, many calculations yield infinities...obvious impossibilities that are a clear signal of the need for a new theory. Although many were forced into accepting a pragmatic approach by simply choosing the theory appropriate to their calculational regime - relativity for cosmological applications and quantum mechanics for particle physics - there are a few cases where the two theories must be merged in order to accurately describe conditions: The cores of black holes and the original singularity at the beginning of the universe. So there is nothing for it...we must understand how these theories merge or except that we do not understand the universe at its most fundamental...with every attempt having failed, String Theory seems to be offering us a way...
History of String Theory

Back in 1968, Gabriele Veneziano, a research fellow at CERN, observed a strange coincidence - many properties of the strong nuclear force seemed to be perfectly described by the Euler beta-function, an obscure formula devised for purely mathematical reasons two hundred years earlier by Leonhard Euler. In the flurry of research that followed, Yoichiro Nambu of the University of Chicago, Holger Nielsen of the Niels Bohr Institute, and Leonard Susskind of Stanford University revealed that the nuclear interactions of elementary particles, modelled as one-dimensional strings instead of zero-dimensional particles, were described exactly by the Euler beta-function. This was, in effect, the birth of String Theory. However, later experiments, in the early '70s, revealed that many of the theory's predictions were at odds with experimental data. As the Standard Model of point particles met success after success, String Theory fell by the wayside. 

Initially, most had seen one major problem with String Theory. The observable properties of the fundamental particles are a manifestation of string vibrations. So, for example, String Theory described vibrational configurations that corresponded to the properties of gluons, the force carriers of the strong force. The theory also generated other vibrational patterns that seemed to have no physical manifestation. These "extra" patterns, however, were soon shown to correspond exactly with the postulated properties of the graviton, the force carrier of the gravitational force, whose existence is predicted, but which has not as yet been experimentally confirmed. The vibrations were found to relate exactly to theorized properties of gravitons. This discovery was not, however, received by the scientific community with open arms; subtle conflicts between it and point-particle physics were again discovered, and the theory was once again abandoned by all but a dedicated few. 

The First Superstring Revolution

In 1984, a paper by Michael Green, then of Queen Mary College, and John Schwarz of the California Institute of Technology presented the fruits of over a dozen years of research often belittled by "mainstream" physicists. The paper not only resolved the conflict between String Theory and quantum mechanics, but also showed that String Theory could encompass all of the four fundamental forces of Nature, and all the matter in existence. The result was the 1st Superstring Revolution, during which physicists around the world rushed to join the research on the very same theory they’d "snubbed" in the past.
The years from ’84 to ‘86 saw more than a thousand papers published on String Theory, showing that the features of the Standard Model could be logically and naturally derived from the new theory. However, the equations of the theory proved difficult - so difficult, in fact, that their exact form could not be determined and approximations had to be used to replace their correct, impossibly complex form. After years of using these approximate methods, they were found inadequate for the types of research being performed. Frustrated scientists, lacking a plan of attack on the dizzyingly complex theoretical calculations, once again abandoned strings and returned to previous projects. 

The Second Superstring Revolution

And then at a conference called Strings 1995, held at the University of Southern California, Edward Witten launched, in dramatic fashion, what came to known as the 2nd Superstring Revolution. He announced a cohesive plan for moving past the approximations used during the 1st Superstring Revolution and thus into even deeper regions of this vast and complex theory. In fact, the full implications of his intervention are still being analyzed by string theorists seeking a way through to what they believe will prove to be the "Theory of Everything."

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