Stephen Hawking, 1942-2018

CurioCity
16 March 2018

Astronomy Black Holes Cosmology Big Bang Theory Universe

Above: Image © NASA

One of the world’s great scientists, Stephen Hawking, passed away on March 14, 2018.

Hawking was a physicist and cosmologist, most famous for his research on the origin and development of the universe.

Did you know? Stephen Hawking became famous among non-scientists thanks to his 1988 book, A Brief History of Time. This book explained Hawking’s complex ideas in plain language. It has sold over 10 million copies.

Click here to watch a video, Stephen Hawking’s Big Ideas Made Simple

Black holes

Above: The centre of a black hole
Image © NASA

Working in the field of astrophysics, Hawking built on ideas first put forth by another brilliant scientist, Albert Einstein.

Black holes are extremely dense. This density causes their gravitational force to be so strong that nothing can pass through - not even light!

The centre of a black hole

Hawking and another physicist, Roger Penrose, found that in the centre of a black hole lies a small space of so much matter that it has infinite amount of gravity. They termed this space a singularity. (This was a revolutionary idea at the time they presented it!)

The edge of a black hole

According to quantum theory, vacuums are full of particles and antiparticles (a particle with the same mass, but opposite electric charge, as its pair). These pairs are called virtual particles. They exist for extremely short periods of time.

At the edge of a black hole, the negatively charged particle in the virtual particle pair will fall in. The other escapes. The escaping particles are called Hawking Radiation due to the immense amount of energy they release.

The particles that fall in have a negative charge. Over time, the continual loss of the positive particles (the negative’s pair) will cause the black hole to shrink, eventually exploding with a huge amount of energy! Hawking theorized that the explosion of a black hole caused the Big Bang around 14 billion years ago, which created our universe.

Did you know? The Big Bang Theory (not the TV show!) is based on the idea that our universe is continually expanding. Scientists believe that the opposite will occur in the future, meaning our universe will begin to compact. This idea called the Big Crunch.

Stephen Hawking had amyotrophic lateral sclerosis, or ALS. That’s a neurodegenerative disease, which means that the body’s nerves and muscles gradually lose their ability to function. This illness is the reason he was in a wheelchair, and used a voice synthesizer to speak.

When he was his early twenties, doctors told Hawking that he had a few years to live. He was 76 when he died.

Did you know? In a 2011 interview, Stephen Hawking gave this advice on life: “Look up at the stars and not at your feet.”