Time Travel Potential

What if you had a time machine?” asked MIT Professor Seth Lloyd at the start of his evening presentation on September 15. “What would you do?”

Suggestions from the audience were quick and creative, with most focusing on traveling back in time to “see the Beatles” or “invest in Apple,” while one student proposed visiting the future to “find great technology and bring it back.” For a mechanical engineer and physicist like Professor Lloyd, thinking about the possibility of time travel – and how it might work within the laws of physics – is “absolutely the most fun thing to do.” And he clearly enjoyed sharing his theories about seemingly improbable concepts, like time travel and teleportation, as he delivered the first Hub Lecture of the new academic year. 

Borrowing its name from Oliver Wendell Holmes’ famous comment that Boston’s State House was “the hub of the solar system,” The Hub at Middlesex lecture series was the inspiration of Dr. Alan Lightman. A noted physicist and author, as well as the father of two Middlesex graduates, Dr. Lightman brought the series to life in 2006 with his enthusiasm for introducing the School’s students to some of the many intellectual luminaries who live and work nearby in the Boston area.

A principal investigator in the Research Laboratory of Electronics at MIT, Professor Lloyd is perhaps best known for his work in the fields of quantum computation and quantum communications. But for his visit to Middlesex, Professor Lloyd turned instead to the idea of time travel and discussed a new theory that he and his colleagues have conceived and even tested at the elementary particle level using photons.

Having reviewed many narratives in folklore, literature, and film, he contended that most time travel stories fall into two categories. In the first, people travel back in time, change something in the past, and return to a reality that has been altered by their actions. The second type of story also involves going back in time, but what happens there is consistent with the future; both remain unchanged.

Professor Lloyd’s theory, he said, falls into the latter category. And in order to explain it in simpler terms, without advanced mathematical calculations, he related it to the famous “grandfather paradox,” in which a woman travels back in time and accidently kills her grandfather before he has met her grandmother, thereby preventing her own birth. In his experiments involving photons, Professor Lloyd said that he and his colleagues have not found that a photon sent “back in time” will destroy itself (and thereby eliminate itself in the future). They have therefore concluded that, at least at the level of elemental particles, time travel is possible and will not alter present-day conditions. Offering a solution to the grandfather paradox, he suggested that perhaps the woman thought she had killed her grandfather, but “a quantum fluctuation deflected the bullet,” sparing his life – and hers.

Allowing that “this is not technology that is ready for commercialization,” Professor Lloyd explained his fascination with topics like these. “My goal is to change the way we think about things,” he stated. “What I get to do is absolutely the most fun thing to do if you want to think about what is possible and maybe change the way that people think about things like time travel.”

The number and quality of questions posed showed that he was indeed successful in that pursuit, and many students stayed to talk with him at length following the lecture’s conclusion.


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