Ten-17 and 10-19 of the radius of an atomic nucleus, or a million billionths of that nucleus. That is the range at which he expects really new physics to be found, and that is where we will find the “theory of everything,” Nobel-prize winning theoretical physicist Steven Weinberg said at Harvard’s Geological Hall this week.
The unification of the four known forces of nature can be found at what Weinberg said was a “crude estimate”–a ballpark range at which “it all seems to hang together.”
“The big question that we face… is, can we find a truly fundamental theory uniting all the forces, including gravitation… characterized by tiny lengths like 10-17 to 10-19 nuclear radii?” said Weinberg, as reported by the Harvard Gazette. “Is it a string theory? That seems like the most beautiful candidate, but we don’t have any direct evidence that it is a string theory. The only handle we have… on this to do further experiments is in cosmology.”
Weinberg referred to the level at which the four forces could be explained in his speech. The two problems that physicists consider to be the less familiar of the four fundamental forces of nature are atomic in level. One force holds a nucleus together. The other is responsible for radioactive decay, changing one particle to another. No theory exists that would explain how all four forces work. The theory of gravity explains one of the better understood of the four forces. Another theory describes the subatomic interactions of electromagnetism and strong and weak nuclear interactions.
Weinberg referred to the far extremes of tininess where the strong and weak forces converge. The strong force weakens at shorter scales and the other two nuclear interactions get stronger at the same scale, apparently.
Gravity, Weinberg said, was strongly suggested to be unified somehow with the other three forces at that same scale, because of the required mass for two protons or electrons to balance their repulsive electrical force.
However, that range is a challenging area for physicists. Required for that kind of investigation is technology beyond what scientists currently have–10 trillion times what we can currently offer physicists in terms of energy is needed, Weinberg said.
Steven Weinberg won the Nobel Prize in 1979 for his work on electroweak theory with Sheldon Glashow and Abdus Salam, in which the relationship between the weak force and magnetism was explained.
By James Haleavy