A Dip into the Wonders of Quantum Gravity, Many Worlds and Black Holes

Maria Violaris

On the 11th November 2019, we held our first quantum information "Flash Talks" event. We invited Adityer Ayer, Sam Kuypers and Nicetu Vidal to give short talks, armed only with a whiteboard, followed by questions and discussion with the audience. All the speakers are DPhil students in the Oxford Physics Department 'Frontiers of Quantum Physics' group led by Professor Vlatko Vedral.

First, Aditya explained the search for signatures of quantum gravity using cosmology, with the help of an image of the cosmic microwave background. The unification of quantum mechanics and gravitation remains one of the greatest mysteries of modern physics, and discovering quantum gravity would be a revolutionary step forward. From contemplating how distant points of the universe communicate to considering how inflation can couple with gravity, we found out how correlations in cosmological data could be investigated to hint at this phenomenon. 

Then Sam took us into a world (or many?) of measurement and thought experiments, arguing convincingly for why the many-worlds interpretation of quantum mechanics should be the most natural conclusion. He explained the testability of the many-worlds interpretation using a thought experiment by Professor David Deutsch - the very thought experiment which led Deutsch to invent the concept of quantum computing.

Finally, Nicetu challenged our minds with the famous black hole information paradox. Simplifying some ideas from quantum field theory and general relativity, we learnt how black hole evaporation seems to violate unitarity - one of the fundamental properties of quantum theory. We were left questioning whether this paradox really requires a profound upheaval of the laws of quantum mechanics or is simply a mistaken mathematical artifact of a very complex calculation. 

All the undergraduates and graduates that had filled Magdalen's Lecture Room A for the event were left with much to think about after the informative and insightful talks, and we look forward to more in the future!