Stephen Hawking died on March 14 at the age of 76. But the physicist lived for 55 years before that with debilitating, nerve-killing ALS.
British physicist Stephen Hawking, who wrote the classic "A Brief History of Time" and transformed our understanding of the cosmos and black holes, died Wednesday at the age of 76.
But decades before his death, at the young age of 21, Hawking was diagnosed with ALS, also known as Lou Gehrig's disease. He wasn't expected to live for more than a few years after that, but he managed to stick around for 55 years before his death (which happened to coincide with Pi Day and Einstein's birthday).
So what is ALS and how did Hawking manage to stay alive for so long?
Amyotrophic lateral sclerosis is a disease that affects the nervous system of the body, slowly destroying nerve cells and becoming more debilitating over time.
It usually begins with some muscle weakness, twitching, or slurred speech. That twitching tends to start in the hands, limbs or feet, according to the Mayo Clinic. Things get worse from there as the disease destroys more cells and degrades motor neurons, eventually affecting a person's ability to speak, eat, swallow, breathe, and eventually, live. On average, people live two to three years after a diagnosis.
But ALS is a pretty variable disease, and doesn't typically have an effect on your brain's ability to think clearly. It also doesn't tend to have an effect on bladder, bowel, or sexual functions. Hawking got married twice, had three children, then lived to meet his three grandchildren, even as ALS slowly gnawed away at his muscle function.
Though Hawking spent most of his life in a wheelchair and was unable to move much of his body, he still had some working face muscles that came in handy. The physicist used a special computer that tracked his cheek muscle movement through a connection to his glasses. That's how he was able to talk to the world and theorize about what might be happening in the cosmos for decades.
Leo McCluskey, medical director of the ALS Center at the University of Pennsylvania, told Scientific American that people who develop ALS when they're younger can live well into their 40s, 50s, and 60s. But he said Hawking’s long stint with the disease was an “astounding” and rare case.
“He's certainly an outlier,” McCluskey said.
For the more than five decades that Hawking had the disease, he dived in to groundbreaking research on how the cosmos formed in the big bang, and wrestled with how it might all end one day. He changed our understanding of black holes, and was the first scientist to unify Einstein's theory of relativity with the tiny, invisible world of quantum mechanics (which had previously been two separate ideas in physics).
Scientists don't fully understand what causes ALS, though a small portion of the cases are hereditary. New CRISPR techniques are helping geneticists learn more about some of the most common genes that drive the neurodegenerative disease.
There is no cure for ALS, though there are a couple of FDA-approved drugs on the market that can slow the progression of the disease.