Who is the greatest genius of all time? As a scientist, I believe that we should first define what genius is to answer that question. Traditionally, it is the ability to be more creative and skilled than anyone else, or the first to glimpse new shores of knowledge. The history of science and technology is rich with great minds, but who is the greatest? For me, it is close between Einstein and Newton, but in Newton's time, there were not many people doing science. However, at the start of the 20th century, when Einstein was working, there were lots of other great scientists such as Paul Dirac, Wener Heisenberg, Niels Bohr and several others. Even amongst them, Einstein was considered special. Some people may say this is a lazy choice, but I have thought long about it, and I feel it is right. The three theories that he published in four papers are some of the greatest ideas ever to come out of the human mind – he proved that atoms exist with his paper on Brownian motion, discovered the fact that light is made up of packets of energy, and the whole field of cosmology and most of modern astronomy were born from Einstein's General Theory of Relativity. He changed forever the way we understand our Universe. Even now, when we talk about the possibility of a big idea changing science, we say "we need another Einstein".