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Stephen William Hawking (1942-present)

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OverviewStephen Hawking

Stephen Hawking is the most renowned theoretical physicist alive. He works at Cambridge University in England as a physics professor. He is a quantum cosmologist - a person who studies the universe at a time when it was so small that atoms had not yet formed. Hawking is best known for his work involving the exploration into the nature of black holes.

Stephen Hawking was born exactly 300 years after the death of Galileo Galilei. He was a normal boy, but he was small and slow to learn to read. He was very interested in how things worked. His father wanted him to become a doctor like himself, but Stephen didn't want to. He was more interested in astronomy.

Important Contributions

In 1973, theoretical physicists Yakov Zeldovitch and Alexander Starobinsky discussed the possibility that radiation could be produced by quantum effects acting just outside of a black hole. Hawking, interested in this idea, further explored it; he verified this assumption and he provided a precise prediction of how much radiation would be produced. This is now called Hawking Radiation. Hawking's calculations have been verified, but the technology to detect Hawking Radiation does not yet exist.

Hawking Radiation occurs when a pair of opposite particles form near the event horizon of a black hole. Normally, near a black hole, the particles spontaneously form from the energy of the black hole, and then they annihilate each other so the energy is given up, so no laws of physics are really violated. But, if one of the particles gets drawn into the black hole, then the other continues to exist, and therefore, the black hole loses some of its mass (by Einstein's equation e=mc^2, this energy loss is a loss in mass).

The escaping particles form a halo around the black hole. As the black hole gets smaller, the halo gets bigger, brighter, and hotter. Finally, when the black hole reaches about one quadrillion degrees (1,000,000,000,000,000 degrees), the black hole explodes in a burst of light and energy. In less than a millionth of a second, it explodes with the energy of one billion atomic bombs.

In 1988, Stephen Hawking published his first book, A Brief History of Time. This book has been the best-selling scientific work in history. It was such a sensation that it was on the London Sunday Times best seller list for 237 weeks, has been translated into about 40 languages, and sold the most copies than any other book (the Bible and Shakespeare are not counted) at about one copy for every 750 people on Earth.

The Disease ALS

Stephen Hawking is unable to move or speak* because of a disease called Amyotrophic Lateral Sclerosis (ALS).

ALS kills nerve cells in the upper spinal cord, and therefore they cannot carry signals from the brain to the muscles of the body. ALS is an incurable disease, and currently affects about 100,000 people world-wide. Most people who are diagnosed with ALS are between the ages of 35 and 55 years old, making Hawking's diagnosis at 21 in 1963 very early. Also, most ALS sufferers die within five years of being diagnosed, while Hawking has survived over three decades with it. 5% of the cases are hereditary. A popular theory about the other 95% is that the affected nerve cells age extremely quickly.

*His speech had been very slurred for several years, but in the late 1980's, Hawking had an emergency tracheotomy, which was a surgical procedure to open an artificial hole in his trachea (windpipe), so that he could breathe. This procedure left him unable to speak.

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