He never allowed his condition—which developed in his early 20s and doctors said would kill him within months of diagnosis—to overcome him. Hawking lived a long and full life, becoming one of the most important scientists and public intellectuals of our time, if not all time.

Despite his undoubted intelligence, Hawking was modest about his gifts. When asked in a 2004 interview with The New York Times what his IQ is, Hawking gave a curt reply: “I have no idea. People who boast about their IQ are losers.”

The interviewer pressed him on how the world could know if he really is a genius physicist, as was often said.

“The media need superheroes in science just as in every sphere of life, but there is really a continuous range of abilities with no clear dividing line,” Hawking said.

“Are you saying you are not a genius?” asked the interviewer.

“I hope I'm near the upper end of the range,” Hawking replied.

According to Mensa, the organization for the world's most intelligent people, which only allows members to join if they pass a difficult test: "IQ or Intelligence Quotient is an attempt to measure intelligence. This means many things to many people but generally the attribute of intelligence refers to quickness of mental comprehension (or mental agility).

"Intelligence is often confused with knowledge, wisdom, memory, or other attributes and in general has a variety of meanings depending on the context in which it is used. The term IQ usually refers to the attempt to measure a person's mental agility.

"There are many standard IQ tests in use around the world. On most intelligence tests, average IQ score is 100, but some tests give different numerical values to the level required for entry into Mensa, in the same way that the same temperature is expressed by different numerical values on the Fahrenheit and Celsius scales."