“Quantum Gravity is the thorniest problem in modern theoretical physics. I'll explain how electromagnetism has led to a consistent quantum theory which is the best tested theory in science. Gravity, which at first sight appears very similar, leads to very strong interactions at high energy and everything breaks down. Latest observations of gravitational waves confirm Einstein's general relativity which describes gravity as a "double copy" of electromagnetism. String theory is one possibility for how to make such a double copy and provides *a* quantum theory of gravity.. but alas only in 10 space time dimensions. It throws up many strange ideas such as "brane-world" which simply emphasise the other big problem - we don't have any experimental probe of gravity at quantum distance scales. Inspite of this it seems real progress is being made and "holography" seems to be the best example of this. Convoluted thinking about black holes has revealed string theory to really be a lower dimensional theory and this seems to be a general lesson about quantum gravity.
Prof Nick Evans (University of Southampton) Nick completed his PhD in collider phenomenology in 1993 at Southampton University. He performed his early research work at Yale and Boston Universities in the US before returning to Southampton in 1999 on a UK government 5 year fellowship. His work centred on strongly interacting particle systems, including composite Higgs models, and he played a large role in applying string theory to study the strong nuclear force and the mechanism of mass generation. Much of his work centres on the structure of the vacuum so in a sense he works on nothing. He is now a Professor at Southampton University and the Director of the Faculty of Physical Science and Engineering Graduate School.”