Hawking gives a talk titled “A Brief History of Mine” to workers at Cedars-Sinai Medical Center in Los Angeles on April 9, 2013.

Hawking gives a talk titled "A Brief History of Mine" to workers at Cedars-Sinai Medical Center in Los Angeles on April 9, 2013.

Hawking gives a talk titled “A Brief History of Mine” to workers at Cedars-Sinai Medical Center in Los Angeles on April 9, 2013.

Hawking gives a talk titled “A Brief History of Mine,” to workers at Cedars-Sinai Medical Center in Los Angeles on April 9, 2013.