Stephen Hawking lived a life which could be observed, but not measured.
Hawking, who was diagnosed with amyotrophic lateral sclerosis when he was 21, spent much of the next fifty years making most people realise that they were actually pretty thick compared to him.
The disease is almost invariably rapidly fatal, and he said that his long life was proof that you should never give up hope.
He wrote several books about the nature of the universe, and the number of people who actually understood them was inversely proportional to the number of people who claimed to have read them.
It is thanks to his work that we know we cannot say for certain where he is, but we do know that some energy has escaped the universe – leaving only vacuum behind.
It is a fact that if you observe something, then you change it, and Stephen Hawking observed more of the universe than anyone else – and changed our reality in ways we have only just begun to comprehend.
Despite his contribution to science, Hawking’s relationship to his own work remained simple and human. He once observed that this would be a pretty poor sort of universe if the people you love didn’t live in it.
And now there is one less.