Is Time Travel Possible?

The premise of time travel — with its promise and pitfalls — has intrigued authors, playwrights and movie directors from Mark Twain, who wrote the novel “A Connecticut Yankee in King Arthur’s Court” in 1889, to H.G. Wells, who invented “The Time Machine” a few years later, to decades’ worth of plots for comic books, movies and popular fiction.

Who could forget the 14 incarnations of Dr. Who? Or Marty McFly, desperate to get back to the future — specifically, 1985 — to ensure his and his siblings’ existence? 

In July, Associate Professor of Physics Jose Lozano gave the lecture “The Physics of Science Fiction: Time Travel and Beyond,” at the Chillicothe Public Library as part of its summer programming. In his introduction, Lozano posed an essential question. “What is time? How is it distorted, for example, by how fast you’re moving or where you are?”

In a spoiler alert, Lozano cited paradoxes that make time travel unlikely. “Traveling to the past to change the present may alter events in the past — for example, consider a person who travels back in time and somehow prevents his mother from conceiving him.”

Then he gave a quick primer on the tenets of physics and how they relate to time travel. Using metal cubes manufactured at the machine shop in the physics department at Bradley, Lozano gave an overview of the four dimensions of space and time and summarized Einstein’s theories on general and special relativity which state that time is not absolute.

He touched on the effects of gravitational lensing, the deflection of light from a distant object by another object (for example, a galaxy) in the foreground. And while answering a question about Stephen Hawking’s theory of black hole extinction, he explained Heisenberg’s Uncertainty Principle.

The somewhat disappointing conclusion: Time travel is impossible. “You can look into the past but not modify it,” he said. “We may be able to fast forward, but not rewind.”

Lozano’s invitation was the brainchild of Catherine Barnett, programming librarian for adult and family programs. “Our summer theme was ‘Reading takes you everywhere,’ so I wanted to find a way to capture the interest of adults. I reached out to Dr. Lozano, and he was very gracious.

“It’s a challenge to address a general audience about a subject you’re an expert in, but he did a good job of balancing that and using examples to illustrate,” she said.