Hawking vs Sagan

Stephen Hawking and Carl Sagan are often named together as the supreme popularisers of science in the late twentieth century, the two figures who did most to bring the cosmos into ordinary homes. They also have a direct link that many people forget: Sagan wrote the introduction to the original 1988 edition of A Brief History of Time.

What Sagan did

Carl Sagan, who lived from 1934 to 1996, was an American astronomer and planetary scientist as well as the most famous science communicator of his generation. He did real scientific work, on planetary atmospheres and the conditions for life, and played a part in NASA's robotic missions. But his greatest impact was as a communicator: his television series Cosmos reached hundreds of millions of viewers, and he championed the search for extraterrestrial intelligence and a sense of wonder at the universe that inspired countless people to take up science.

What Hawking did

Hawking shared Sagan's gift for reaching the public, and A Brief History of Time arguably surpassed even Cosmos in sheer sales. But Hawking was first and foremost a theorist working at the deepest level of physics, with Hawking radiation and the singularity theorems to his name. His public communication grew out of, and ran alongside, frontier research.

An honest verdict

The fairest summary is that the two excelled at overlapping but different things. Sagan was the greater communicator and a capable scientist; Hawking was the deeper theorist who also happened to communicate brilliantly. Both understood, as Hawking put it in his own approach to explaining science, that knowledge shut away from the public does only half its work. Their connection through that 1988 introduction is a fitting symbol of a shared mission.