Do We Need String Theory for Quantum Gravity?
The strong, weak, and electromagnetic interactions all have consistent, relativistic and quantum mechanical descriptions in terms of pointlike particles, but Einstein’s theory of gravitation has long resisted a similar treatment, because of severe ultraviolet divergences.
String theory solves these problems, but it introduces a new length scale, perhaps 16 orders of magnitude below what can be tested experimentally.
Dr. Dixon will describe recent theoretical progress in showing that a particular pointlike theory of gravity, called N=8 supergravity, might also be quantum mechanically consistent.
In particular, N=8 supergravity has been shown explicitly to have no ultraviolet divergences in perturbation theory through the four-loop order. Dr. Dixon will also discuss the possible implications of these results.