Stephen Hawking Stephen Hawking

This artist's impression shows the surroundings of the supermassive black hole at the heart of the active galaxy NGC 3783 in the southern constellation of Centaurus. M. Kornmesser/ESO hide caption

toggle caption
M. Kornmesser/ESO

British cosmologist Stephen Hawking gives a talk to workers at Cedars-Sinai Medical Center in Los Angeles on April 9. Eric Reed/Cedars-Sinai/AP hide caption

toggle caption
Eric Reed/Cedars-Sinai/AP