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Remembering Stephen Hawking

The groundbreaking astrophysicist died at the age of 76

March 15, 2018
By Jennifer Hackett
Jemal Countess/Getty Images

Stephen Hawking presenting at an event about space exploration in New York City in 2016.

Stephen Hawking, one of the world's most famous scientists, died Wednesday. Hawking was an astrophysicist who studied cosmology, the science of the origin and development of the universe. In addition to his research prowess, Hawking wrote popular books about cosmology for the public. For many, he was the first person to come to mind when asked to name a scientist.

Hawking entered graduate school at Cambridge University in England in 1962. His work was based on Albert Einstein's theory of general relativity. It stated that three-dimensional space is connected to a fourth dimension: time. Einstein described this concept, known as spacetime. He proposed that the presence of matter and energy causes spacetime to curve. That curvature creates gravity, the force that attracts objects to one another. General relativity predicts that in some areas of spacetime, called black holes, gravity is so strong that even light can’t escape.  

Hawking dedicated his career to studying and making theories about black holes. When he was in school, black holes were only theoretical objects. Around the same time, astronomers predicted that a black hole would form when a star explodes and then collapses in on itself. It wasn't until the 1970s that astronomers' telescopes found evidence of black holes.

Since black holes suck in all matter and energy within a certain radius, nothing should ever come out of a black hole. Yet Hawking theorized that if a black hole could shrink, it would emit a small amount of energy. This type of energy is now called Hawking radiation. The Fermi space telescope, which was launched in 2008, is on the hunt for Hawking radiation to confirm his theory.

Universal History Archive/UIG via Getty Images

An illustration of what a black hole may look like.

LIVING WITH ALS

When he was 21, Hawking was diagnosed with a disease called amyotrophic lateral sclerosis (ALS). It’s also called Lou Gehrig’s disease after a famous baseball player who died of the disease in 1941. ALS destroys nerve cells that help control muscle movement.

Doctors told Hawking he would live for just two more years. He went on to live for another 55 years, until the age of 76. For most of his life, Hawking used a wheelchair to get around. This led Hawking and his wife, Jane, to advocate for better accessibility for those with physical challenges at Cambridge University, where he was a professor.

Because of his illness, Hawking eventually lost the use of his vocal cords. He used a computer software program to communicate. At first he would select words on a screen with his hand that would then be said aloud by the computer program. Later as his condition progressed, they adapted the computer to respond to movements in his cheek muscles.

A GIANT OF SCIENCE

Unlike most scientists, Hawking became a household name. One reason he was so well-known is that he wanted to share what he learned with everyone, not just other scientists. He wrote many science books about his research and about the history of cosmology. His first book, A Brief History of Time, has sold more than 10 million copies since it was published in 1988. It is one of the most read books about science in the world.

Hawking also made guest appearances on many television shows. He appeared as a cartoon version of himself that he voiced in four episodes of The Simpsons. He also had guest spots on The Big Bang Theory and Star Trek: The Next Generation. Dozens of other movies, TV shows, and comics have referred to him or his research.

For many scientists and students, Hawking was a source of inspiration. “Not since Albert Einstein has a scientist so captured the public imagination and [been admired by] tens of millions of people around the world,” said Michio Kaku, a physicist at the City University of New York in an interview.

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