From Space Dust We Come, to Space Dust We Go

 
 

Sean Mooney takes a look back on the extraordinary life and career of Stephen Hawking. 

At 21, Stephen Hawking was diagnosed with motor neuron disease, and was given a life expectancy of two years. Although death did not come in that time frame, over the years, the disease severely reduced his bodily control. Crucially for his research, however, his mind was left untouched. He did not let his disability stand in his way, and once said: “Look up at the stars and not down at your feet.”

This perseverance, coupled with his intellect, led him to carve out an illustrious career in the field of cosmology. For 30 years, Hawking held one of the most prestigious academic posts in the world, the Lucasian Chair of Mathematics, a professorship at the University of Cambridge that was formerly held by Isaac Newton.

For 30 years, Hawking held one of the most prestigious academic posts in the world, the Lucasian Chair of Mathematics, a professorship at the University of Cambridge which was formerly held by Isaac Newton

One of the main contributions Hawking made to science was regarding black holes. Matter exerts a gravitational pull on everything, attracting more matter to it. Black holes are sufficiently massive that nothing can escape their pull, not even light itself. The fact that there is no light coming from black holes is why they appear black. However, Hawking showed that black holes are in fact glowing, and emit what is now called Hawking radiation. This radiation leaks out from black holes, causing them to evaporate over time. Black holes continue to shrink and eventually disappear. This process is extremely slow for the average black hole, but miniature black holes release radiation rapidly and explode out of existence.

There are two incompatible theories that can explain much of what we see in the universe. Einstein’s theory of general relativity describes enormous structures in the universe, such as black holes and the orbits of the planets. Quantum mechanics, on the other hand, is a theory that precisely describes the behaviour of stuff on the smallest scales, like atoms. These two theories have forever been mutually incompatible and one of the biggest questions in all of science is formulating a grand unified theory that agrees with both general relativity and quantum mechanics. To explain why black holes emit radiation, Hawking applied the small-scale theories of quantum mechanics to black holes. This was the first step in the ongoing effort to find a grand unified theory.

Hawking realised that the Big Bang was rather like the collapse of a black hole in reverse

There is no such thing as a true vacuum; even in empty space, new particles and their anti-particle pair are constantly popping into existence and then immediately destroying each other. When this occurs at the edge of a black hole, however, it is possible that either the particle or anti-particle gets pulled into the black hole while the other escapes. Then the pair of particles can no longer annihilate each other and in this way, the black hole is seen to emit radiation, as these particles appear to be coming from the black hole.

The universe is expanding, in that all distant galaxies are moving away from each other at an ever-increasing rate. Hawking collaborated with Roger Penrose to publish a series of theorems which showed that, since the universe is expanding, space and time must therefore have had a beginning in the distant past. Hawking realised that the big bang was rather like the collapse of a black hole in reverse.

In the 1980s, Hawking showed that tiny variations in the distribution of matter right after the big bang could explain why galaxies are spread out across the universe. These tiny deviations from uniformity gave rise to the planets, stars, and galaxies of today and this was an important discovery in cosmology.

Hawking may have gained prominence in the scientific community for his work on black holes but his success extended well beyond academia and he inspired a generation to study science and ponder the universe. In spite of his condition, he was a master at science communication. Hawking stated that “Equations are just the boring part of mathematics” and he had a talent for describing technical ideas simply.

In the 1980s, Hawking showed that tiny variations in how matter was distributed right after the Big Bang could explain why galaxies are spread out across the universe

In 1988, he authored A Brief History of Time: From the Big Bang to Black Holes, using his scientific insight to translate complex ideas for a non-specialist audience. Since its release, the book has gone on to sell more than 10 million copies and has been translated into dozens of languages. He also featured in a range of popular media, including appearing on television shows such as The Simpsons and The Big Bang Theory.

Hawking’s remains have been laid to rest in Westminster Abbey, in a place of pride near the final resting place of Newton. Newton once said that “If I have seen further it is by standing on the shoulders of giants” and it is fitting that Hawking held the same position as him at the University of Cambridge since Newton was the first to formulate how gravity works and Hawking has arguably taken it further than anyone else. Likewise, the discoveries that Hawking has made will no doubt provide the bedrock for future theories for decades to come.

Advertisements