He wore pajamas and a bathrobe, and a swollen bare foot was propped up on an ottoman. That was the figure cut by the revered science-fiction author Arthur C. Clarke the one time that I, along with a few other Scientific American editors, met him. It was October 1999, and he was in New York City for a few days while on an extremely rare trip outside of his adopted home country, Sri Lanka, for medical reasons.

He had invited us to come over for a chat at his hotel, which happened to be the historic Hotel Chelsea, where he had stayed in the mid-1960s while working on his best known work, 2001: A Space Odyssey. (In the 1993 edition of the book, he wrote of "months of brainstorming with [director] Stanley [Kubrick]—followed by (fairly) lonely hours in Room 1008... where most of the novel was written.")

Clarke gently berated us for not taking cold fusion seriously enough. Most researchers had dismissed it a decade earlier, but he still believed that a revolutionary discovery could come from the experiments of the smattering of remaining devotees.

He may have even repeated the first of "Clarke’s Laws": "When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong." For physicists and mathematicians, "elderly" means over 30. (His two other famous laws were that discovering the limits of the possible requires venturing a bit into the impossible, and that any sufficiently advanced technology is indistinguishable from magic.)

When Clarke was not yet elderly, 27 in fact, he wrote an article in the magazine Wireless World describing how a satellite in an equatorial orbit with a radius of 42,000 kilometers (26,000 miles) would remain over the same location of the earth, and how three spaced around the orbit could relay radio signals to anywhere on the globe. The concept was not new with Clarke, but he popularized the idea. Nearly two decades later, the first such geostationary communications satellite was launched (it relayed television signals of the 1964 Olympics in Tokyo to the U.S.) at the same time Clarke was at work on 2001 at the Hotel Chelsea.

Clarke suffered from post-polio syndrome and reportedly had trouble breathing before his death at 90 on Tuesday. During his lifetime, he wrote or co-wrote scores of books, both fiction and nonfiction, and won numerous awards. Spacecraft have been named in honor of his work, and entities including an asteroid, an orbit, a species of dinosaur and several awards have been named after him. Many scientists, astronauts and writers have credited him with inspiring them to take up their own careers.

His impact, you might say, was indistinguishable from magic.