The time-traveling exploits of Back to the Future duo Marty McFly and his DeLorean may not be such a stretch after all. In his new book, The Fabric of the Cosmos: Space, Time and the Texture of Reality, theoretical physicist Brian Greene ’84 suggests that time travel and teleportation are well within the realms of quantum mechanics, a conceptual framework of physics that emerged in the 1930s.

Greene kicked off his 15-city tour in Cambridge on Wednesday to promote his latest effort. A Harvard alum, Greene says being in Cambridge brings back quite a few memories.

“I decided to come to Harvard at the last minute. After sending in the forms saying I wasn’t coming, I changed my mind,” he jokes. “I started as in-between math and physics, but I took a course with [Mallinckrodt Professor of Physics] Howard Georgi, who’s still here, and it really impressed me how fantastic it was that the math could be used to describe the real world. So by the end of freshman year I was pretty certain, and I was physics from then on.”

After graduating summa cum laude, Greene won a Rhodes scholarship to Oxford, where he received his doctorate. Since then, he has taught at Cornell University, where he is currently a joint professor of physics and mathematics. Additionally, he bears the title of co-director of the Institute for Strings, Cosmology and Astroparticle Physics at Columbia University.

In 1999, Greene published his first book, The Elegant Universe, for which he was a Pulitzer Prize finalist. The book presented the idea of string theory, a concept that is gaining more credibility among the scientific community as a potential form of the Unification theory for which Einstein searched in his later years. String theory proposes that all matter is made up of infinitesimally small strings and what they form depends on their vibration, which moves like the vibration of a violin string.

“I think Einstein would have loved string theory. The thing to bear in mind is Einstein himself recognized the limitations of his own General Theory of Relativity. That’s why he was looking for something to go beyond it,” Greene says. “I think string theory, in many ways, does exactly what he was hoping. It puts together his own theory, general relativity, with this other framework that is undeniably correct: quantum mechanics.”

The mathematics of string theory gives rise to the almost unfathomable possibility that the universe may have more than three spatial dimensions. After an experimentally induced collision of particles, energy may be lost to the extra eight predicted dimensions, Greene explains, emphasizing the point by smashing his fists together and transforming his fingers into the extra dimensions. This way, it may be possible to indirectly “see” these missing dimensions.

In The Fabric of the Cosmos, Greene addresses a wealth of intergalactic enigmas that would normally make most people cringe, but strips away their convoluted veneer to present the underlying workings with a comfortable clarity. He expounds on already familiar concepts such as the Big Bang, and challenges our everyday notion of past, present and future.

“Who doesn’t worry about the passage of time? Who doesn’t worry about getting older? Who doesn’t have nostalgia of the past?” Greene says. “I think these kinds of feelings can be placed in a broader context when you understand how physics looks at time, and that’s part of what the book is about.”

Greene’s prodigious talents as a scientist were evident at as early an age as five, when he used to multiply 30-digit by 30-digit numbers on large pieces of construction paper he would tape together. After exhausting all of the textbooks and resources at his junior high school, Greene remembers walking door to door at Columbia University with a note from his sixth grade teacher asking someone to challenge the gifted boy. Finally, he was apprenticed to a graduate student in mathematics and continued to study with him throughout high school.

Greene seems to leave a lasting impression on anyone he meets. Former schoolmate and current Boston native Dr. Paul Ketro, who stopped by to see Greene’s talk Wednesday night at the Brattle Theatre, laughs as he recalls his old friend constantly practicing judo, a Japanese martial art, and proving he could do a thousand sit-ups during the lunch period in third grade.

While a student at Harvard, Greene worked with Menzel Professor of Astrophysics James M. Moran on a project to determine the shape of an ionized gas cloud near the center of the galaxy.

“I knew even when Brian was a junior that something special was going on,” says Moran. “Brian was clearly headed for a brilliant career in theoretical physics.”

Graustein Professor of Mathematics Shing-Tung Yau remembers receiving a phone call years ago from an unknown researcher in England informing him that the three mathematical structures discussed in his recently published “Calabi Yau Manifolds” were all essentially the same structure. Greene was the researcher, and Yau first disregarded his claims but was later astonished to realize Greene was correct. Yau subsequently convinced Greene to work with him for the following two years. “In those days, it was more like he was teaching me than me leading the research,” Yau says.

Greene may also be the only person on earth who can discuss supersymmetry and the Moulin Rouge soundtrack in the same conversation. In his occasional visits outside the realm of physics, he revels in music and theatre. If he weren’t a physicist, he says his dream would be to perform music, though he’s not convinced he’s very good at it. Such a predisposition towards the performing arts may have taken root because of the influence of Greene’s composer father. While at Oxford, Greene participated in improvisational theater, and later at Cornell, he acted in Harold Pinter’s “Betrayal,” which coincidently proceeds backwards through time.