Lisa Randall: String Theory

Physicist

Lisa Randall studies theoretical particle physics and cosmology at Harvard University. Her research connects theoretical insights to puzzles in our current understanding of the properties and interactions of matter. She has developed and studied a wide variety of models to address these questions, the most prominent involving extra dimensions of space. Her work has involved improving our under-standing of the Standard Model of particle physics, supersymmetry, baryogenesis, cosmological inflation, and dark matter. Randall’s research also explores ways to experimentally test and verify ideas and her current research focuses in large part on the Large Hadron Collider and dark matter searches and models.

Randall has also had a public presence through her writing, lectures, and radio and TV appearances. Randall’s books, Warped Passages: Unraveling the Mysteries of the Universe’s Hidden Dimensions and Knocking on Heaven’s Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World were both on the New York Times’ list of 100 Notable Books of the Year. Higgs Discovery: The Power of Empty Space was released as a Kindle Single in the summer of 2012 as an update with recent particle physics developments.

Randall’s studies have made her among the most cited and influential theoretical physicists and she has received numerous awards and honors for her scientific endeavors. She is a member of the National Academy of Sciences, the American Philosophical Society, the American Academy of Arts and Sciences, was a fellow of the American Physical Society, and is a past winner of an Alfred P. Sloan Foundation Research Fellowship, a National Science Foundation Young Investigator Award, a DOE Outstanding Junior Investigator Award, and the Westinghouse Science Talent Search. Randall is an Honorary Member of the Royal Irish Academy and an Honorary Fellow of the British Institute of Physics. In 2003, she received the Premio Caterina Tomassoni e Felice Pietro Chisesi Award, from the University of Rome, La Sapienza. In 2006, she received the Klopsteg Award from the American Society of Physics Teachers (AAPT) for her lectures and in 2007 she received the Julius Lilienfeld Prize from the American Physical Society for her work on elementary particle physics and cosmology and for communicating this work to the public.

Randall has also pursued art-science connections, writing a libretto for Hypermusic: A Projective Opera in Seven Planes that premiered in the Pompidou Center in Paris and co-curating an art exhibit for the Los Angeles Arts Association, Measure for Measure, which was presented in Gallery 825 in Los Angeles, at the Guggenheim Gallery at Chapman University, and at Harvard’s Carpenter Center. In 2012, she was the recipient of the Andrew Gemant Award from the American Institute of Physics, which is given annually for significant contributions to the cultural, artistic, or humanistic dimension of physics.

Professor Randall was on the list of Time Magazine's "100 Most Influential People" of 2007 and was one of 40 people featured in The Rolling Stone 40th Anniversary issue that year. Prof. Randall was featured in Newsweek's "Who's Next in 2006" as "one of the most promising theoretical physicists of her generation" and in Seed Magazine's "2005 Year in Science Icons". In 2008, Prof. Randall was among Esquire Magazine's “75 Most Influential People.”

Professor Randall earned her PhD from Harvard University and held professorships at MIT and Princeton University before returning to Harvard in 2001. She is also the recipient of honorary degrees from Brown University, Duke University, Bard College, and the University of Antwerp.

  • Transcript

TRANSCRIPT

Lisa Randall: Well okay, so first of all what problem is string theory trying to solve? String theory is trying to reconcile quantum mechanics and gravity. And let’s take a step back and see what we mean by that, because in fact we do understand gravity. Einstein’s theory of general relativity describes gravity, and it’s been tested. We’ve seen evidence of general relativity. Quantum mechanics we know very well has been tested on atomic skills. The point is that there exists scales that we can’t test. They’re much too small for experiments to be done – in distance, or much too high energy – where we wouldn’t know how to make predictions. It would look inconsistent. In other words, in the regime of large things where cosmology or general relativity applies, we do fine. It’s just quantum mechanics is negligible on those scales. On small scales, atomic scales we can ignore gravity because gravity is so weak. But there exists tiny distances or very high energies where both forces (22:24) would, in principle, be important. Those aren’t ones where we can experimentally test; but even theoretically we believe we should have a theory which could work at all distance scales. It’s just the fact that we haven’t been able to make experiments to test those yet doesn’t mean there shouldn’t be a theory that describes it. So people have been looking for a candidate theory of what’s called “quantum gravity” for some time. So string theory is a theory of quantum gravity. Or it’s a candidate theory of quantum gravity. And it’s based on the idea that fundamentally we don’t have elementary particles, but we have fundamental oscillating strings. And particles are the oscillation of those strings. And if you . . . You can say how could we not notice those strings in the particles. But if you think about it, if the strings are really tiny, they look like particles. We can’t see it. To see that it’s actually a string, you’d have to see the additional oscillations that a strong can have. And to do that you’d have to be able to test the energies that it would take to make a string oscillate. And it turns out we need to start having __________ approach anywhere near those energies at this point.So essentially what we’re doing is we’re taking . . . It’s sort of an interaction in the sense that we take some ideas from string theory, such as extra dimensions and branes, and see what could be the implications for particle physics. And if, for example, it was found that we were right, string theorists would have to find ways to predict the kind of geometry we propose. And if that . . . After we did our work . . . At first when we did it, everyone said, “Oh this never happens in string theory.” But after we did it, people found ways that this could happen in string theory. But also some of the more theoretical work such as the infinite work dimension of space, maybe that goes back to string theory. There are possibilities that people haven’t thought about yet. So . . . and it goes back and forth.

 

 

Recorded On: 11/2/07


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