Mathematician and theoretical physicist. Since 1979 Hawking has been Lucasian Professor of Mathematics at Cambridge University, a post famously held by Sir Isaac Newton. His early research on relativity led him to study the Big Bang, the creation of the universe and black holes. From the 1960s Hawking has suffered from a progressive neuromotor disease known as amyotrophic lateral sclerosis (ALS), causing him severe disability. He uses a wheelchair and speaks through an electronic voice synthesizer. He continues to work and has produced several best-selling science books including A Brief History of Time (1988), Black Holes and Baby Universes (1993) and The Universe in a Nutshell (2001). In the 1980s, encouraged by Margaret Gowing (who was both a Trustee and an historian of science), the Gallery embarked on an active policy of commissioning portraits of scientists, on the grounds that science and technology make a contribution to British culture which is not always well understood by the general public.