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Calculating the probability of possible solutions for the universe

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Testing superstring theory

Murray Gell-Mann
Scientist

Views | Duration | ||
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151. The fourth quark | 537 | 03:16 | |

152. Salam and Ward | 1106 | 01:18 | |

153. Sheldon Glashow; enemy of superstring theory | 1457 | 01:55 | |

154. Crucial tests for string theory | 804 | 01:03 | |

155. Superstring theory | 783 | 03:32 | |

156. Testing superstring theory | 1039 | 03:27 | |

157. Calculating the probability of possible solutions for the universe | 505 | 01:34 | |

158. Boundary conditions in the context of string theory | 427 | 01:09 | |

159. Cosmology, astrophysics and particle physics | 544 | 03:56 | |

160. Working on quantum mechanics, the work of Everett | 1013 | 03:01 |

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[Q] *Are you concerned in any way, given your... the way you practiced physics which was very closely tied in with experimental results, are you in any way disturbed by the fact that it seems unlikely that there can be a... an acid test of superstring theory, in the usual sense of that...?*

* *Well, I don't know what you mean by 'the usual sense.' It has already got some successes in predicting the Einsteinian theory; it predicts supersymmetry, which could play a very important role in preserving the big ratios that we observe among masses in the presence of radiative corrections; and curing the singular properties of the scalar particles. The… so supersymmetry is desirable in itself and it's predicted by superstring theory. Super… supersymmetry can also be verified by observation, and I hope that the LHC is sufficiently energetic to permit that. We don't know exactly what the supergap is, how high you have to go to encounter the superpartners of the known elementary particles, but if it's too high it sort of defeats the purpose—the one we just discussed—of maintaining the big ratios in the face of radiative corrections and so on, so I don't the supergap can be so very high. Moreover some people speculate that the superpartner of the top quark, the top squark, so to speak, might be lighter than the top quark. Could be discovered perhaps even without the LHC. All of those things are encouraging. Now I suppose there could be some naysayers who, even if supersymmetry is confirmed, will say, well, that doesn't prove superstring theory. But one can make a great many post-dictions as well as predictions: one can explain, perhaps, a large number of the facts about the standard model that are now known or will be known in the future. And I'm sure there are also corrections to the standard model and those could be verified; there may even be astrophysical or cosmological consequences that can be… that can be checked. I don't see any… anything wrong with the idea of comparing superstring theory with observation.

[Q]* Some of the practitioners of M-theory have been making provocative statements that there is really no need any longer for big accelerators and it's… no… along these lines of 'testing' in the traditional sense, hat those are not the sorts of tests, other than...*

Well, I don't find that very congenial. I think that's absurd. Of course we should, to the extent possible , carry our experiments to higher energies, try to understand what's going on there and see how it compares with theory. But I do agree that besides accelerator building and accelerator experiments, it's essential to do a lot of theory. We have to extract the predictions from superstring theory.

New York-born physicist Murray Gell-Mann is known for his creation of the eightfold way, an ordering system for subatomic particles, comparable to the periodic table. His discovery of the omega-minus particle filled a gap in the system, brought the theory wide acceptance and led to Gell-Mann's winning the Nobel Prize in Physics in 1969.

**Title: **Testing superstring theory

**Listeners:**
Geoffrey West

Geoffrey West is a Staff Member, Fellow, and Program Manager for High Energy Physics at Los Alamos National Laboratory. He is also a member of The Santa Fe Institute. He is a native of England and was educated at Cambridge University (B.A. 1961). He received his Ph.D. from Stanford University in 1966 followed by post-doctoral appointments at Cornell and Harvard Universities. He returned to Stanford as a faculty member in 1970. He left to build and lead the Theoretical High Energy Physics Group at Los Alamos. He has numerous scientific publications including the editing of three books. His primary interest has been in fundamental questions in Physics, especially those concerning the elementary particles and their interactions. His long-term fascination in general scaling phenomena grew out of his work on scaling in quantum chromodynamics and the unification of all forces of nature. In 1996 this evolved into the highly productive collaboration with James Brown and Brian Enquist on the origin of allometric scaling laws in biology and the development of realistic quantitative models that analyse the influence of size on the structural and functional design of organisms.

**Tags:**
LHC

**Duration:**
3 minutes, 28 seconds

**Date story recorded:**
October 1997

**Date story went live:**
29 September 2010