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Stephen Hawking enjoys freefall on a special ‘vomit comet’ flight. Image: Jim Campbell/Aero-News Network

Stephen Hawking was widely regarded as one of the best physicists of our age, so it was a huge loss when he died on 14 March this year. Here are a few things you might not know about one of history’s most celebrated scientists.

1) He discovered that black holes aren’t black

A lot of Stephen’s work was on black holes; objects that are so massive and so compact that their gravity makes it impossible for even light to escape.

So you might imagine that black holes would be black, but Stephen thought that they might actually glow. Using quantum theory – the physics of the Universe’s smallest particles – he suggested that some of the black holes might emit something called Hawking radiation.

One way to imagine it is to think of a pair of particles popping into existence next to the black hole. Usually, these particles would collide and cancel out again. But near a black hole one particle could fall into the black hole as its twin fled, causing a faint, eerie radiation.

2) He had a rare, life-threatening disease

Stephen had amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease. ALS affects your motor neurons; cells in the brain and body that control muscle movement.

You may remember that several years ago, people started sharing videos of themselves getting soaked in ice water. This was known as the ice bucket challenge, and it was a fundraiser for ALS treatment and research!

Stephen was diagnosed in the early 1960s, and doctors said he probably only had two more years to live. Luckily, the disease progressed much slower than usual.

3) He used a computer to speak

Stephen lost his voice in 1985 after a life-threatening infection, and relied on a special computer that could read aloud words he wrote using a special device.

His computerised voice was cutting edge technology, but over time new voices were developed that were closer to normal speech. Stephen rejected the new voices, choosing to keep using the old computer.

Over time, his computer became fairly unique. Stephen was worried that it might break down and he’d need a new voice, so a team of computer scientists wrote a program that imitated the way Stephen’s unique voice worked. He received a brand new computer that sounded just like him!

4) He wrote a bestselling book

Quantum physics and relativity are two of the hardest ideas in science. Just the right topics for a best-selling book, right?

Stephen Hawking thought so. In 1988, he published a book called ‘A Brief History of Time’. The book covers lots of the big ideas in physics, from the Big Bang to black holes. It is written in easy-to-read language, but it is still famously difficult to understand.

An estimated 10 million copies of ‘A Brief History of Time’ have been sold, which makes it one of the most popular books every written.

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