Stephen William Hawking CH CBE FRS FRSA was an English theoretical physicist, cosmologist and author. At the time of his death on March 14, 2018, he was research director at Theoretical Cosmology Center, University of Cambridge, UK.
In his 21st year, Hawking was diagnosed with motor neuron disease (MND) also known as amyotrophic lateral sclerosis "ALS" or Lou Gehrig's disease. His doctors predicted that he had just about 6 months to live, but he lived an extraordinary life for 76 years and contributed immensely to the field of cosmology, defining our universe in ways it had never been done before.
MNDs are a group of progressive neurological disorders that destroy motor neurons, the cells that control essential voluntary muscle activity such as speaking, walking, breathing, and swallowing. When there are disruptions in the signals between the motor neurons and the muscle, the muscles do not work properly. The muscles gradually weaken and may begin wasting away, and over time, the ability to control voluntary movement can be gradually lost.
Here's a brief walk through Hawking's theories on the universe: