Unwholesome gas given off by Time Snails. One of the great mysteries of the universe is where time goes to. Seconds, minutes, days, and years go by, but where too? The answer: time flows into wormholes. If it didn't, the universe would fill with time until it exploded. But if time simply flowed into wormholes and into other dimensions, they woud explode. This is where Time snails come in. They perch on the edges of wormholes and consume time, which is promptly digested. In doing so, they give off the gas known as gneff. Basicly, gneff is a time fart.
The physicist detected the scent of gneff, so he knew he was near a wormhole.