As news of famed physicistspread Tuesday night, friends and fans of the great scientist were quick to mourn and remember him on social media.
Some of the tributes came from famous names in their own right.
Many remarked on Hawking's remarkable brainpower, and many shared memorable quotes from the physicist.
While Hawking easily solved intellectual problems, physical challenges proved a tougher opponent. He was diagnosed at just 21 with a form of amyotrophic lateral sclerosis known as Lou Gehrig's disease that gradually paralyzed him. He got around via wheelchair and spoke through a computer system operated with his cheek.
Many took inspiration from Hawking's continuing to learn and work despite his physical limitations.
There was a certain scientific symmetry in Hawking's birth and death dates.
First published March 13, 9:45 p.m. PT.
Update, 10 p.m. PT: Adds more reactions.