Hawking,
who died on March 14 aged 76, had shown how one could not only manage to stay
alive with even a deadly motor neuron disease but also break scientific
boundaries.
**
Stephen William Hawking, a brilliant
scientist and the best-known physicist since Albert Einstein, was born in
Oxford, UK on January 8, 1942—exactly on the 300th death anniversary of Galileo Galilei, the
Italian natural philosopher, astronomer and mathematician, with whom he shared something
in common: Hawking, like Galileo, who was admonished by ecclesiastical
politicians “not to hold, teach, or
defend” the Copernican theory “in any way whatever, either orally or in
writing”, too had to fight to be heard. Of course, Hawking’s struggle was not
because of the clergy but due to a degenerative motor neuron disease called
amyotrophic lateral sclerosis that he was diagnosed with at the age of 21. It
slowly ate away his muscles, confining him to wheelchair. His condition turned
worse in 1985 when he caught pneumonia and had a tracheotomy, for he lost
whatever little control he had till then on his speech once for all, besides
becoming a dependent on 24-hour care. Since then, he had been communicating
through the electronic voice synthesizer.
Though his body slumped, his
spirit soared high, for his mental faculties remained untouched by the disease.
With that of a child’s curiosity, he pursued his ambitious intellectual goal,
“Complete understanding of the universe, why it is as it is and why it exists
at all”, by entering Cambridge in 1962 as a PhD student working on ‘Properties
of Expanding Universe’ under the supervision of cosmologist, Denis Sciama and
rose to become the Lucasian Professor of Mathematics in 1979. After retiring in
2009, he worked as the Dennis Stanton Avery and Sally Tsui Wong-Avery Director
of Research in the Department of Applied Mathematics and Theoretical Physics
until his death.
It is in 1970 that his
exceptional intelligence first came into limelight with the now famous
‘singularity theorem’ that he proposed jointly with the mathematician Roger
Penrose, which showed that general relativity implies that singularity lay at
the starting point of our universe, the Big Bang.
This interest in singularities
naturally led Hawking to work on black holes. His initial work on black holes
suggested that a black hole can only increase, never decrease in size—which
sounds obvious, for nothing that gets close to a black hole can escape from
being swallowed by it and thus gains mass.
He had also shown that a black hole can never be split into smaller
ones—even, say through collision of two black holes. He also argued that the
event horizon’s ever-expanding surface area was analogous to another quantity
known as entropy which could only grow.
And these two—increasing surface area of a black hole and increasing
entropy of the universe were oddly similar.
As Hawking announced his result in
1970, a young physicist called, Jacob Bekenstein boldly questioning: “what if
this wasn’t just an analogy?” suggested that the surface area of a black hole’s
event horizon might be a measure of the black hole’s entropy. This however was
turned down by Hawking and many other physicists, for black holes and entropy didn’t seem to go
together.
But when he set out to prove
Bekenstein was wrong, he realised that Bekenstein is “basically correct” and to
prove it he brought together general relativity and quantum theory, a feat
which nobody else managed. And thus came in 1974, his brilliant thesis published
in the Journal, Nature under the title, “Black Hole Explosions?” wherein
using quantum theory, he predicted that black holes—the regions of space-time
having a gravitational field so immense that nothing can escape it—emit
“thermal radiation” and hence “one would expect it to lose mass” which
phenomenon “in turn would increase the surface gravity and so increase the rate
of emission” because of which black hole would “have finite life”—i.e., the
larger the size of the black hole, the longer it takes to evaporate, while
miniature black holes vanish much faster.
This shocking and controversial
publication had also kick-started a long-lasting debate: when black holes
evaporate, what would happen to the information trapped in them? There could be two possibilities: either it is
somehow encoded in the radiation emitted by the black hole, or it is vanished.
Surprisingly, Hawking claimed that the information—mass, position, charge,
etc.—disappears for ever, hearing which the American Physicist, Leonard
Susskind argued that Hawking was simply wrong. For, Hawking’s assumption violates
the basic principle of quantum mechanics: the conservation of information. And
this debate raged, of course, fairly in a collegial manner, for decades,
including the fun-loving Hawking wagering an Encyclopaedia that information was
indeed lost in back holes. However, in 2004 Hawking finally concedes that he
lost the bet, for Susskind is right but with a qualification: information was
only returned to the universe in a corrupt form that was virtually impossible
to read and to this effect he did publish a paper next year. But it failed to
convince many Physicists.
In the 1980s, Hawking came up
with a brilliant idea of explaining the Big Bang in quantum mechanical terms.
He believed that the quantum fluctuations in an inflationary universe spread
galaxies in the universe. Working with James Hartle, he argued that when the
universe was extremely tiny, quantum theory implies that the distinction
between space and time was extremely fuzzy. It means that early universe did
not have meaningful boundaries in time or space. However, some physicists
believe that his quantum equation, supposed to explain the universe in its
early stage does not say anything meaningful. And, this idea is still being
debated.
Incidentally, it is this model
that he explained in his bestselling book, A Brief History of Time
(1988) that instantly made him a celebrity among the masses. Although he authored/edited
by then quite a few influential books, of course jointly with others—The Large scale Structure of Spacetime (1973),
General Relativity: an Einstein Centenary
Survey (1979), Superspace and
Supergravity (1981), The very Early
Universe (1983)—it is this book— A
Brief History of Time— that brought him closer to even common man besides
being on the Sunday Times best-seller list for a record-breaking 237 weeks,
besides being translated into as many 40 world languages.
Moving on, this iconic
cosmologist of his time had this to advise to the fellow scientists who
assembled at Cambridge to celebrate his 75th birthday in 2017: “…Be curious, and however
difficult life may seem, there is always something you can do, and succeed at.
It matters that you don’t just give up.” And the life of this wheelchair-huddled
man which is an amazing manifestation of willpower and determination, is in
itself a testimony to what Prof Stephen Hawking said.
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