William Shakespeare frequently draws inspiration from the, often contradictory, nature of appearance and reality: Richard III hides his murderous ambition behind a diffident and servile manner; Macbeth presents a figure of utter loyalty to the King before having him brutally murdered; Falstaff's rumbustious, drink-sodden nature hides a melancholy and eventually broken inner man.

He was diagnosed with motor neurone disease at 21

It is entirely appropriate, then, that Professor Stephen Hawking should draw upon the Bard, specifically Hamlet, for the title of his latest work, The Universe in a Nutshell.

Rarely has there been such a public figure whose outward appearance so belied the person inside.

Stephen Hawking was born in Oxford in 1942. It was while he was in his final year as an undergraduate at University College, Oxford, in 1963, that he was diagnosed as having Amyotrophic Lateral Sclerosis (ALS).

A form of motor neurone disease, ALS is a degenerative and incurable illness which attacks the body's motor cells, leading to paralysis. It usually proves fatal within five years.

Survivor

Against all odds, Hawking has survived and, while his body wasted, his power of speech became curtailed and he came to rely on carers for almost all his needs, his mind, which had been good enough to earn him a First in Natural Science, flourished.

Distinguished predecessor: Sir Isaac Newton

Moving to Cambridge, he gained a doctorate in cosmology, was a Research Fellow and, in 1979, became Lucasian Professor of Mathematics - a post once held by Sir Isaac Newton.

There the story of this interesting, brilliant but still rather obscure academic might have ended. But then came The Book.

In 1988, Hawking published A Brief History of Time. The work, a magisterial exposition of theories about the beginning and the end of the Universe, which he wrote to pay for his care costs, was a huge best-seller.

Pioneering work

Ten million copies were sold in 40 languages. It became a pioneering magnum opus of popular science, even though cynics called it The Greatest Selling Book No-one Read. Hawking was f�ted by presidents and monarchs and even had cameo roles in The Simpsons and Star Trek.

Einstein predicted the "theory of everything"

Thirteen years on, The Universe in a Nutshell is the long-awaited sequel to A Brief History. In his new book, he brings cosmological theories up to date and allows himself to speculate on matters philosophical.

Central to his new thesis is a belief that scientists may have already discovered the Holy Grail of science or, as he calls it, "the theory of everything".

Albert Einstein posited this idea, which brings together Quantum Theory (the study of the very small) and General Relativity (the study of the very large) into a unification of all matter and forces, during the early part of the 20th Century.

Eleven dimensions

It is only now that Hawking and his colleagues are coming to an understanding that space-time, which we understand in four dimensions, height, width, length and time, may exist in no fewer than 11 dimensions. If proved, such a theory, he says, explains "the origin and fate of the Universe". Heady stuff indeed.

I don't think the human race will survive the next thousand years unless we spread into space

Stephen Hawking

The quotation which provides the book's title seems to reveal much about the man. In Act II of Hamlet, the Prince declaims: "O God, I could be bounded in a nut shell and count myself a king of infinite space, were it not that I have bad dreams."

Hawking's prediction for the future of mankind, which has provoked criticism in scientific circles, seems itself to have been the product of "bad dreams."

"I don't think the human race will survive the next thousand years unless we spread into space" he recently told a journalist. "There are too many accidents that can befall life on a single planet."

GMO threat

Chief among these, he says, is the possibility that, through accident or design, humanity may be wiped out by a genetically engineered virus. He has also recently warned that carbon dioxide emissions would leave the Earth like Venus with "boiling sulphuric acid."

But should this headline-grabbing pronouncement be seen merely as a natural part of the marketing publicity which surrounds any book launch?

Dr Benny Peiser, senior lecturer in social anthropology at Liverpool John Moores University and an expert on natural catastrophes, says that Hawking's dire prognostications are "unreasonable."

Could a virus wipe out humanity?

Dr Peiser is concerned about "apocalyptic prophecies and doomsday predictions" which generate irrational fears among the general public.

And he adds: "I feel this aggressive scare-mongering, be it about global warming or genetic engineering, does not only lack any credible evidence, but it is irresponsible coming, as it does, from a highly respected scientist."

There is no doubt that Hawking's new book will be a bestseller, just as there is no doubt that the man himself will remain a scientific superstar.

But the idea that the professor is an omniscient sage, something he has always fiercely denied, may have to be taken with the tiniest pinch of space dust.