?Hawking - AFP

A brief history of Stephen Hawking, 1942-2018
(The Philippine Star) - March 22, 2018 - 12:00am

MANILA, Philippines — Stephen Hawking spent his scientific life exploring some of the deepest questions a human caught in the Einsteinian opera of space and time could ask.

Although Einstein himself never really accepted it, his general theory of relativity predicted that if enough mass or energy were concentrated at one point, space would sag like mattress and eventually close itself off, creating a black hole from which nothing, not even light, could escape.

It would be Hawking’s fate to explore these imagined monsters and ask what their presence portends for the universe, and for those of us who live inside it.

The universe had a beginning

?In 1965, when Hawking was 23, British mathematician Roger Penrose proved that if Einstein’s theory of gravity, general relativity, was correct there is a point of infinite density – a singularity – at the center of a black hole.

In 1970, building on work in Hawking’s doctoral dissertation, he and Penrose show that there had to be a singularity at the beginning of time – in other words, a Big Bang.

That is to say, he showed that the universe had a beginning.

How black holes behave (and misbehave)

1970 – Hawking shows that the area of a black hole’s event horizon – a spherical surface marking the point of no return – can only increase, never decrease, as stuff falls into a black hole or it collides and merges with other black holes

1971 – He suggests that mini black holes much smaller than stars created in the Big Bang could be peppering the universe.

1974 – He shocks his colleagues and the world by showing that black holes will leak and explode when quantum effects – the weird laws that describe subatomic behavior – are taken into account.

1976 – Hawking says exploding black holes add randomness and unpredictability to the universe, forever erasing information about what might have fallen into a black hole.

Quantum physicists object, saying the universe can’t forget, initiating a 40-year argument about the fate of information.

Hawking concedes in 2004 but does not say how information is preserved in a black hole, and the argument continues to this day.

A universe with no boundaries

1982 – Using a mathematical conceit called imaginary time, Hawking and James Hartle, a theoretical physicist at the University of California, Santa Barbara, propose a model of a self-contained universe that has no boundary in space or time, and thus no place or time when the laws of physics break down.

In their picture of cosmic history, space-time is like a globe of the Earth. Time starts at the North Pole and goes south as the universe gets fatter. Asking what came before the Big Bang, in this case, is like asking what is north of the North Pole, they said.

Moreover, just as nothing weird happens at the North Pole of the Earth, nothing strange happens to the laws of physics at time zero. Earth abides and so does physics, obviating the need for a creator.

‘A Brief History of Time’

1988 – Hawking publishes “A Brief History of Time.” It stays on the London Times best-seller list for four years, starting a gold rush of science books by prominent scientists.

1991 – Errol Morris directs a documentary of the same name about Hawking and his life.

2007 – Hawking is briefly free of gravity at last on a “vomit comet” flight in Florida.

2012 – Hawking stars in the opening of the Paralympic Games in London

2015 – “The Theory of Everything,” a movie based on a book by his ex-wife, Jane Wilde, wins an Oscar for Eddie Redmayne.

He can’t make his mind up about aliens

2010 – Hawking tells the Discovery Channel, “If aliens visit us, the outcome would be much as when Columbus landed in America, which didn’t turn out well for the Native Americans. We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet.”

2015 – He presides over the announcement of Breakthrough Listen, a $100 million search for signals from extraterrestrial civilizations.

“In an infinite universe there must be other occurrences of life,” he said. “Or do our lights wander a lifeless universe? Either way, there is no bigger question.”

But he is sure about time travel. In 1991, he enunciated what he called the chronology protection conjecture, that will, as he put it, “keep the world safe for historians.” It says that the laws of physics do not allow time machines.

In 2016, working with Andrew Strominger of Cambridge University and Malcolm Perry of Harvard, Hawking took a small step toward a solution of the infamous information paradox. He announced that information about what falls into a black hole might be preserved on the surface, or event horizon, of a black hole.

The universe will remember us, which is no small thing, he declared.

If the rules break down in black holes, they may be lost in other places as well, he warned. If information disappears into a gaping maw, the notion of a “past” itself may be in jeopardy – we couldn’t even be sure of our own histories. Our memories could be illusions.

“It’s the past that tells us who we are. Without it we lose our identity,” he said. – New York Times News Service

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