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of String Theory and Its Derivatives |
String theory is a label applied to a variety of formulations of different natures and purposes. Some applied to subatomic particles and others to astronomical structures and cosmology. A timeline structure is suitable, even essential, for presenting its history.
In 1867 Lord Kelvin (Sir William Thomson) published an article in the Proceedings of the Royal Society of Edinburgh, Vol. VI, 1867, pp. 94-105, in which he proposed that atoms consisted of vortex rings in the ether of space. Such vortex rings could be linked together to form complex structures. The title of Kelvin's article was "On Vortex Atoms."
Atoms were known to exist because of the constant proportions demonstrated in chemical reactions. However this article was from a time before the existence of electrons was known. Experiments by J.J. Thomson in 1897 led to the discovery of the electron as a fundamental building block of matter. Experiments by others led them to the same conclusion and the name electron was coined by someone else.
In 1919 the German mathematician Theodor Kaluza formulated a theory based upon the General Theory of Relativity but involving four spatial dimensions rather than three. From his theory Kaluza got electromagnetism as an implication. This held out the possibility of uniting gravity and electromagnetism. Albert Einstein liked Kaluza's work and supported its publication.
(Kaluza was German but his name was Slavic which leads people to identify him as being Polish but his name is not Polish but instead that of a small Slavic minority in Eastern Germany.)
In a book of mathematical functions he discovered a name for this function. It was called Euler's beta function. Somehow this story got changed into the notion that he discovered the beta function as a function that would explain the strong force. That version neglects the year he spent deriving the mathematical function. In the book he only found out that the function had a name.
Who would have thought, from the title of Veneziano's article, "Construction of a Crossing-Symmetric Regge-Behaved Amplitude for Linearly Rising Regge Trajectories," that it would launch a major intellectual effort.
This effort by Veneziano is taken to be the foundation of string theory although at that point it was not known that the analysis could be interpreted as pertaining to strings. Another researcher at CERN, Mahiko Suzuki, at the same time independently developed the same analysis as Veneziano.
The quantum field approach to particle physics involves Feynman diagrams for the elemental particle interactions, which may involve infinite quantities. The procedure for the removal of these infinities is called renormalization.
The S matrix theory approach distained visualizations, Feynman diagrams and renormalization and reduced everything to obtaining the matrix of the interactions of particles. The outstanding proponent of S matrix theory was Geoffrey Chew of the University of California at Berkeley. String theory appeared to be a victory for Chew's S matrix theory.
The Old String Theory is dead! Long live the New String Theory!
John Schwarz and Andre Neveu of Princeton University also created such a reformulation of string theory. The new string theory had the advantage that it did not require for consistency with Special Relativity and quantum theory the existence of a tachyon and a world of 26 dimensions. It only required a world of ten dimensions. This modified string theory became known as superstring theory. This was the first, but not the last, case of a name being coined which appears to be meaningful but is nevertheless opaque.
A world that is a narrow tube would appear to be one dimensional but a position around the circular cross section of the tube would constitute a second dimension. String theorists envision some multi-dimensional compactification of space existing at every point in space.
I don't like that they are not calculating anything. I don't like that they don't check their ideas. I don't like that for anything that disagrees with an experiment, they cook up an explanation--a fix-up to say "Well it still might be true." For example, the theory requires ten dimensions. Well, maybe there is a way of wrapping up six of the dimensions. Yes, that is possible mathematically, but why not seven? When they write their equations, the equations should decide how many of these things get wrapped up, not the desire to agree with experiment. In other words, there is no reason whatsoever in superstring theory that it is not eight of the ten dimensions that get wrapped up and that the result is two dimensions, which would be completely in disagreement with experience. So the fact that it might disagree with experience is very tenuous, it does not produce anything, it has to be excused most of the time. It does not look right.
This is from Superstrings: A Theory of Everything (1988), pp. 194-195.
But superstring theorists have not yet shown that their theory really works. They cannot demonstrate that the standard theory is a logical outcome of string theory. They cannot even be sure that their formulism includes a description of such things as protons and electrons. And they have not yet made even one teeny-tiny experimental prediction. Worst of all, superstring theory does not follow as logical consequence of some appealing set of hypotheses about nature. Why, you may ask, do the string theorists insist that space is nine-dimensional? Simply because string theory doesn't make sense in any other kind of space. …
This is from Interactions: A Journey Through the Mind of a Particle Physicist (1988), p. 25.
The article showed that the conditions for superstring theory to imply a version of the standard model were the same as the conditions which defined a Calabi-Yau manifold. Furthermore the parameters of the standard model such as the masses of the particles corresponded to characteristics of the Calabi-Yau manifold.
Edward Witten gave a lecture at that conference in which he outlined the nature that string theory would take in the future. He proposed that there were dualities involved among the five versions of string theory such that they could all be considered as manifestations of a single theory. However the unification of the five versions of string theory came at a price: The number of dimensions of the world has to be eleven rather than ten. But there isn't a consistent string theory of eleven dimensions. There is an eleven dimensional version involving membranes, two dimensional analogues of the one dimensional strings. Witten gave the name M-theory to the theory that was to replace strings. But it was not so different after all. If one dimension of a membrane is wrapped around a circle, say a small circle, it is a tube that effectively is one dimensional.
The Old String Theory is dead! Long live the New String Theory!
The physicist Lee Smolin in his 2006 book Trouble with Physics makes the point that the physics profession is overcommitted to the notion of string theory.
[…]Despite the absence of experimental support and precise formulation, the theory is believed of its adherents with a certainty that seems emotional rather than rational.[…]Nearly every particle theorist with a permanent position at the prestigious Institute for Advanced Study, including the director, is a string theorist. The same is true of the Kavli Institute for Theoretical Physics. Eight of the nine MacArthur Fellowships awarded to particle physicists since the beginnings of the program in 1981 have also gone to string theorists. And in the country's top physics departments (Berkeley, Caltech, Harvard, MIT, Princeton, and Stanford), twenty out of the twenty-two tenured professors in particle physics who received PhDs after 1981 made their reputations in string theory or related approaches. (Page xx of the Introduction.)
This was as of 2006. Here in 2015 the situation is about the same: String theory on the verge of explaining everything but not having yielded one verifiable prediction. Most theories have a set of free parameters whose values are established by the particular universe we have. Richard Dawid, in his book String Theory and the Scientific Method points out that string theory has no free parameters and it is the only scientific theory with this characteristic.
It seems that
String Theory is an elegant answer in search of an appropriate question.
Perhaps the string theorists have forgotten that the phlogiston theory of heat and the luminiferous aether for the propogation of electromagnetic waves were elegant solutions to real problems, but still they were not right.
Some former string theorists are more trenchant in their criticisms. Peter Woit, in his book Not Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law argues that string theory’s lack of rigor has left its practitioners unable to distinguish between a scientific speculation and a genuine analytical result.. The overall result is a disaster in terms of the waste of funding and scientific talent. Lee Smolin speaks of being challenged at string theory conferences as to his right to being there.
What can be said is that the journey that the term string theory represents is strewn with discarded formulations and interpretations that were once thought to be revolutionary developments in science. These were discarded because of theoretical flaws, but it is unlikely that the an empirical failure of a version of string theory would have resulted in anything other than a reformulation of string theory and a continuation of the quest.
The following is a graph of the number of article published per year in string theory from 1973 to 2008.
Despite more than 800 published articles per year from 1998 and beyond no testable prediction of string theory has, as of 2015, been developed. However, what has come out of the effort is valid propositions in mathematics.
The process sees to involve two parts. The first part involves formulating a model in terms of Lagrangian mechanics and rigorously analyzing it mathematically. The second part involves linking the mathematical results ingenuously but nonrigorously to entities in the physical world. The first part is string theory as such; the second part is more or less yarn theory.
Father Divine, a cult leader of the 1920's through the 50's, once said
The trouble with this world is that there are too many metaphysicians that don't know how to tangibilitate.
The trouble now may be that there are all too many metaphysicians who know how to tangibilitate and they do so freely.
Furthermore, as it is, string theory is an example of an attempt to execute an all-too-prevalent false syllogism in science. The false syllogism is:
To draw that conclusion it would have to be established that Proposition B is true only if Proposition A is true, which is a much stronger proposition than what is used in the false syllogism.
At this stage string theory is collecting witty characterization by people who are not true believers; e.g.,
String theory is The Theory of More than Everything. .,
And then along came the Bogdanov brothers.
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