When he was 21 years old, doctors told Stephen Hawking that he only had a few years left to live.

Hawking, the world-renowned physicist, was diagnosed with early-onset ALS, also known as Lou Gehrig's disease, which would gradually paralyze every part of his body. Luckily, Hawking would defy the odds and live another 55 years since the day he was given a death sentence.

"When you are faced with the possibility of an early death, it makes you realize that life is worth living and that there are lots of things you want to do," he said.

Indeed, he did a lot of things. He went on to have a long career in science in which he explored the bottomless gravitational pits in the universe known as black holes.

In 1974, Hawking made a breakthrough discovery thanks to his rigorous calculations: Black holes weren't "perfectly black." They would leak radiation and heat, which would cause them to shrink and eventually fizzle away. To put it simply: "When is a black hole not black? When it explodes."

While Hawking's mind was at its peak, his body kept deteriorating. He was able to retain some control over his speech up to 1985. But on a trip to Switzerland, Hawking came down with pneumonia so severe that doctors asked his wife Jane if she wanted to shut off his life support.

She said no, and this began Hawking's next chapter. He survived the illness, but his voice was gone forever.

When a computer expert, Walter Woltosz, heard about Hawking’s condition, he demonstrated the program he had written. Hawking would be able to communicate through the computer via an infrared beam that he was able to activate by tensing one muscle in his right cheek. It allowed him to speak, write books, compose emails, and browse the internet.

Hawking (and the world) became very attached to how his synthesizer voice sounded that when he was given a new synthesizer with a more clear voice, he asked them to replace it with the original.

Hawking was a man who pushed the limits in his personal, professional, and intellectual lives. He wrote best-selling books, visited every continent, became a father, appeared on "The Simpsons," went up on a hot-air balloon, and took part in a zero-gravity flight.

He didn't live life in fear of death. “My expectations were reduced to zero when I was 21," he says. "Everything since then has been a bonus.”

There's a lot we can learn from Hawking's life. He showed us that there is no boundary to human endeavor and that the human spirit can overcome even the most debilitating blows.

"However difficult life may seem, there is always something you can do and succeed at," he says. "It matters that you don’t just give up.”

READ.

On the origins of the universe: The Big Bang. Wormholes. Time travel. In his book, A Brief History of Time, Hawking explains a range of subjects in cosmology in a way that the average person could understand. One reader summarized it well: "Isn't it amazing that a person can read a book like A Brief History of Time, and come away feeling both smarter and dumber than before he started? What a universe we live in!"

On a brief history of his life: In his memoir, My Brief History, Hawking recounts his improbable journey — from his upbringing to his diagnosis of ALS at age 21 to struggling to gain a foothold in the world of physics and cosmology.

WATCH.

On becoming the master of the universe: This fascinating documentary gives us a glimpse of Hawking's quest for a "Theory of Everything." This "holy grail" hypothesis could explain everything — from supernovae to black holes. Here's how Hawking unlocked the mysteries that ultimately dubbed him 'master of the universe.'

On questioning the universe: In his TED Talk, Hawking asks some of the biggest questions in the universe. Where did humans come from? How did the universe come into being? Are we alone? Is there alien life out there? And what is the future of the human race? His answers are even more stunning than the questions.

On unpacking his scientific discoveries: This interview will blow your mind. It brings together two of the best: Hawking and astrophysicist Neil deGrasse Tyson. Tyson breaks down the conversation into several parts, in which he explains Hawking's many ideas, including the mind-boggling theory around non-negative energy density.

On the Theory of Everything: The movie, The Theory of Everything, is based on Hawking's life, and it focuses on his relationship with his first wife Jane Wilde. Over the course of their marriage, Hawking's body collapsed while his academic renown soared. His diagnosis tested their relationship and dramatically altered the course of both of their lives.

TECHNIQUES TO TRY.

Curiosity is the key to a full life: Hawking's curiosity was contagious. He saw himself as a child who never grew up in that he was always asking "how" and "why" questions. Hawking was constantly on the hunt for answers, never passively accepting expert claims as scientific fact. Ask questions, test your hypotheses, and most importantly, make space for wonder. “Remember to look up at the stars and not down at your feet," Hawking said. "Try to make sense of what you see and wonder about what makes the universe exist. Be curious."

Stay malleable: Hawking once said, "Intelligence is the ability to adapt to change." This is a powerful mental framework because it rejects blind dogma and embraces the unknown. The world is constantly evolving, and so are we. Only the most stubborn and intellectually lazy people are unwilling to change after they are presented with new information. "The greatest enemy of knowledge is not ignorance," he says, "it is the illusion of knowledge."

Communication is humanity's greatest strength: In today's polarized world, it's difficult to have a productive conversation. Hawking reminds us that effective communication is the key to bringing our ideas to life. “For millions of years, mankind lived just like the animals. Then something happened which unleashed the power of our imagination. We learned to talk and we learned to listen," he says. "Speech has allowed the communication of ideas, enabling human beings to work together to build the impossible." Remember, speaking and listening are both required in order to have a functioning society that promotes great ideas.

Cherish what gives you life: Despite his worsening condition, Hawking married Jane Wilde in 1965, saying that his marriage gave him “something to live for." It meant he had to find a job, find ways to support his family, and start taking his doctorate work seriously again. Even though both of Hawking's marriages ended in divorce, it's important to find people, moments, or life events that give you hope to keep going in the face of great darkness.

Imperfect things are beautiful things: The biggest blunder of Hawking's career was his early belief that everything swallowed up by a black hole must be lost forever. He discovered that there is one thing that does in fact escape from black holes: radiation. But without his initial erroneous belief, Hawking would have never advanced on his theory of black holes. Think about it this way: If the universe was perfect, humans wouldn't exist. “Next time someone complains that you have made a mistake, tell him that may be a good thing," he said. "Because without imperfection, neither you nor I would exist.”

Don't let circumstance break your spirit: Hawking’s life demonstrates that human identity doesn't have to be tied to its physical circumstances. He never allowed his condition to dictate his internal state. "My advice to other disabled people would be, concentrate on things your disability doesn't prevent you doing well, and don't regret the things it interferes with," he said. "Don't be disabled in spirit as well as physically."

Remember that you can escape the black hole: We've all felt like we've been sucked into the depths of a black hole at some point in our lives. But Hawking's discovery that heat can escape black holes can serve as a great metaphor for our own lives. “Black holes ain’t as black as they are painted. They are not the eternal prisons they were once thought," he said. "Things can get out of a black hole, both to the outside, and possibly, to another universe. So, if you feel you are in a black hole, don’t give up. There’s a way out.”

QUOTES TO REMEMBER.

"Intelligence is the ability to adapt to change."

"Life would be tragic if it weren't funny."

“I have sold more books on physics than Madonna has on sex.”

"The past, like the future, is indefinite and exists only as a spectrum of possibilities."

"When one's expectations are reduced to zero, one really appreciates everything one does have."

"To confine our attention to terrestrial matters would be to limit the human spirit."

"Work gives you meaning and purpose, and life is empty without it."

"People won't have time for you if you are always angry or complaining."

"If human life were long enough to find the ultimate theory, everything would have been solved by previous generations. Nothing would be left to be discovered."

"However difficult life may seem, there is always something you can do and succeed at. Where there's life, there's hope."

“So remember, look at the stars and not at your feet.”

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