Daniel Cutting is a final year PhD student at the University of Sussex visiting the IFIC from the 13th - 15th of November. During his PhD he has been performing large scale simulations of first-order phase transitions in the early Universe. During a first-order phase transition, bubbles of the true vacuum form, and upon collision produce gravitational waves. Daniel is particularly interested first-order phase transitions at the electroweak scale as if the transition is sufficiently strong it can produce a gravitational wave signal that would be observable for the upcoming LISA mission. In general Daniel is interested in other cosmological or astrophysical phenomena that can be observable through gravitational waves, for example inflation, cosmic strings and compact objects.