FILE - In this March 6, 2017 file photo, Britain's Professor Stephen Hawking delivers a keynote speech as he receives the Honorary Freedom of the City of London during a ceremony at the Guildhall in the City of London. Hawking, whose brilliant mind ranged across time and space though his body was paralyzed by disease, has died, a family spokesman said early Wednesday, March 14, 2018. (AP Photo/Matt Dunham, File)
FILE - In this March 6, 2017 file photo, Britain's Professor Stephen Hawking delivers a keynote speech as he receives the Honorary Freedom of the City of London during a ceremony at the Guildhall in the City of London. Hawking, whose brilliant mind ranged across time and space though his body was paralyzed by disease, has died, a family spokesman said early Wednesday, March 14, 2018. (AP Photo/Matt Dunham, File) Credit: Matt Dunham

Hanover — Dartmouth College professor of physics Robert Caldwell on Wednesday remembered the late Stephen Hawking as an inspirational figure whose research and personal story pushed the limits of science and human courage.

As a young postdoctoral student in the mid-1990s, Caldwell worked in Hawking’s research group at Cambridge University, studying gravitational waves and other phenomena implicated in the work of the revered theoretical physicist and cosmologist, who died at home in Cambridge, England, early Wednesday morning.

Caldwell recalls the way faculty and graduate students hushed when, during the department’s occasional group lunches, Hawking piped up to ask a question via his speech synthesizer, which he used to communicate over several decades of living with amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease.

“When he asked a question, everyone stopped,” Caldwell said. It was partly out of courtesy, because Hawking’s sentences took a long time to formulate, but also “because if he asked a question, it was pretty significant.”

The two scientists did not work together directly, but Caldwell, who uses gravitational waves to probe the edges of the universe, is in some ways plumbing the implications of Hawking’s earlier research into the quirks of quantum physics, gravity and black holes.

Hawking occasionally accompanied his postdocs down to the local pub, Caldwell said, although, 20 years (and a few pints) after the fact, the conversations were difficult to remember. During department parties, Caldwell saw Hawking take to the dance floor, zipping back and forth in his wheelchair.

The Dartmouth professor visited Cambridge this past summer to see Hawking one last time, for his 75th birthday celebration. (Hawking was born in January, but the party took place in the summer for better weather.) The international physics eminence gave a brief autobiographical talk about his life and work, or, as Caldwell put it, “his trajectory through space-time.”

“He was a hero to a lot of people — to me,” Caldwell said. “It’s kind of funny to say, but the fame that he achieved — I think it’s amazing that someone in my line of work can reach such heights.”

Caldwell added, laughing, “He was on The Simpsons. And Star Trek!”

Rob Wolfe can be reached at rwolfe@vnews.com or 603-727-3242.