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I have read a variety of articles and books about string theory that relate the various initial discoveries that ultimately lead to a theory we know now as "string theory" (and its descendants such as M-theory, branes, etc.).

But, is any single individual noted as being the father (or, mother) of string theory. Could it be Susskind? Who was the first person to recognize that actual vibrating strings were at the core of the original work?

I know this is rather recent history but that makes it easier -- someone here lived through this time.

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  • $\begingroup$ I've seen Schwarz and even Veneziano credited as being the father, though Susskind is there just as often. $\endgroup$ – HDE 226868 Jul 11 '15 at 16:23
  • $\begingroup$ Yes I know Schwarz and Veneziano which is one of the main reasons for my question -- who actually did the key step that resulted in "string theory" to be known as string theory? Also, one paper I read seemed to hint that vibrating strings were not the first realization but rather vibrating membranes came first but I am not sure about that and I can't even remember the paper where this idea came from. $\endgroup$ – K7PEH Jul 11 '15 at 16:43
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I will reduce the detailed history to principal highlights. Any of the physicists mentioned below can be considered "fathers" of string theory depending on which aspect of it is considered "the core". The problem with a straightforward answer is that the mathematical formalism was originally developed for purposes that had little to do with modern string theory, and there were several additional insights by different people that made it viable, any of which can be seen as its "true birth".

The earliest candidate for a "father" is perhaps Gabriele Veneziano, who used Euler's beta function as a scattering amplitude in his 1968 paper. At the time unification of quantum fields and gravity was not on the agenda, the issue was working out a theory of strong interaction, and that is what Veneziano introduced his formula for. By 1970, Nambu, Nielsen and Susskind concluded that Veneziano's formula would be based on more than a mere analogy if particles were treated as vibrating strings. This led to the so-called dual resonance models of strong interaction, but they were abandoned in 1973 in favor of quantum chromodynamics.

The original string theory was purely bosonic, fermions were added in 1971 by Ramond and led to the discovery of supersymmetry and superstrings. The number of required dimensions was reduced from 26 in bosonic theory to 10. One of the bosonic vibration modes was a massless particle of spin two, which as Schwarz, Scherk, and independently Yoneya, pointed out in 1974, were exactly the properties of hypothesized graviton. Moreover, in late 1970s supersymmetry was used to unify field theories with gravity independently of strings, in the so-called supergravity. So while original string theory of strong interactions was discarded, the mathematical formalism lived on as a candidate for quantum gravity.

It was not taken seriously however until 1984, when Green and Schwarz discovered that superstring theories produce counterterms that eliminate so-called quantum anomalies. These are mathematical complications that prevent quantized field theories from manifesting classical symmetries, and make them inconsistent. This came to be called the "first superstring revolution", which attracted many new researchers to the field, including Witten, who initiated the "second superstring revolution" in 1995.

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  • $\begingroup$ I had read a bit of the work done by the early group and I think that I had ruled out Veneziano as a candidate Father primarily because he was working towards something totally different and I am not sure if he even knew of the import of his early work. Of those early guys, Susskind is the only one I would vote for but then I am not sure if his work is more important than Green and Schwarz. But, I think the notion of strings first came from Susskind which is the reason I lean toward him. Maybe Susskind is the father but since Green and Schwarz nurtured the work they can be mothers. $\endgroup$ – K7PEH Jul 14 '15 at 1:29
  • $\begingroup$ @K7PEH It's not always like Einstein and relativity, sometimes father's identity just can not be established :-) It was somewhat similar with quantum mechanics, Planck thought he was still doing classical physics until 1905. $\endgroup$ – Conifold Jul 16 '15 at 18:40
  • $\begingroup$ I agree with your comment. I originally posted my question because quite recently I saw two other articles that gave the "father" title to Susskind. I would be happy to hear Susskind admit in deep voice: "String, I am your Father". $\endgroup$ – K7PEH Jul 16 '15 at 19:10
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This seems relevant: ${}{}{}{}{}{}{}{}{}{}$

enter image description here

Image obtained from Chapter 9 of A Brief History of String Theory: From Dual Models to M-Theory by Dean Rickles. Its legend in the book reads:

Extract from Weinberg's letter of support for John Schwarz's nomination for California Scientist of the Year. Image source Caltech archives [letter dated Feb. 13, 1986; Gell-Mann papers: Box 5, Folder 10]

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