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David Cassidy from UCL Physics. David is a lecturer at UCL and has been since 2013.⠀ ⠀ David is conducting experiments at UCL that aim to understand how atoms made from matter and antimatter interact with gravity. These entities, which are called positronium atoms, are made from an electron and a positron bound together. They can be difficult to work with because the particle-antiparticle pair can destroy each other via a process called annihilation in a few hundred billionths of a second. However, using lasers they can be put into more stable excited states, which can also be manipulated by electric fields. ⠀ ⠀ David and his group hope to use these properties to create a slow beam of positronium observe its gravitational free-fall. Finding out if antimatter interacts via gravity in the same way as ordinary matter, or if it could possibly be affected by some sort of “anti-gravity” is one of the most important unanswered questions in modern physics.⠀