New Faculty: Michael Schulz Ties Relativity
To Quantum Mechanics With String Theory
Thanks to theories of relativity, science has developed ways to explain the relationships among energy, gravity, and mass, and with the rise of quantum physics, we have gotten a glimpse into the workings of subatomic particles. These hypotheses and laws have proven extraordinarily useful in expanding humankind's understanding of the universe and of the individual parts that the universe comprises.
There's just one problem.
"It's for some of the most interesting questions that you don't have this nice separation between relativity and quantum mechanics," says Bryn Mawr theoretical physicist Michael B. Schulz. "What is the earliest history of the universe? What are black holes, really? What is matter made up of at its most fundamental level? Are the elementary particles fundamental or is there something else that's more fundamental? These are, I think, the most exciting questions."
UNIFYING ALL MATTER AND FORCES
Relativity is concerned with gravitational forces, and applies to more sizable bodies, while quantum mechanical theory describes the interplay among individual particles, the tiniest bits of matter yet discovered. Applying the former to the latter produces contradictory results. Reconciling these incompatible theories to explain all matter and forces in the universe in a uniform way is the goal of string theory, Schulz's primary research interest.
"We don't have a consistent theory that explains all observations," says Schulz, who joined the College in 2007 as an assistant professor of physics. "The minimum goal of string theory is to incorporate everything that has been explained, all the successes of those other theories, into one consistent theory."
String theory is an approach to quantum gravity in which the "point particles" of elementary particle physics—fundamental to all matter and all forces—are replaced by small vibrating strings.
"An electron, if you look at it very closely, is just a small vibrating string, vibrating in one particular way. A photon, the quantum of light, if you look at it really closely, is a little string vibrating in a different way. Everything is made up of strings in string theory," Schulz says. "There is every indication that this modification cures the short-distance problem of quantum field theory plus general relativity in a consistent way."
A big challenge for string theory is that for realistic particle physics to be extracted from it, the theory must account for six unknown dimensions. In applying string theory and its applications to quantum field theory, cosmology, and particle physics, much of Schulz's work seeks to broaden the understanding of "compactifications," the condensation of these theoretical dimensions to help explain in a more realistic way the physics of the four known dimensions of height, width, depth, and time. Within the framework of string theory, Schulz is interested in constructing a consistent gravitational quantum theory encompassing an extension of the standard model of particle physics together with general relativity at sufficiently large distances.
"The different solutions of string theory lead to different quantum field theories," Schulz says. "My work seeks to generalize the toolbox through which realistic quantum field theories like the standard model and its extensions can ultimately be realized as large-distance limits of string-theory solutions."
Prior to Bryn Mawr, Schulz pursued postdoctoral research at Caltech and the University of Pennsylvania, and held positions at the Linear Accelerator Center and the Institute for Theoretical Physics at Stanford University, where he obtained his Ph.D. A small liberal-arts college might seem an odd choice after so many years at large research universities, but Schulz has found Bryn Mawr to be an excellent fit.
"Bryn Mawr is a unique place," he says. "As a liberal arts college that takes research very, very seriously, it has graduated an impressive number of women who go on to get Ph.D.s in physics. That was very attractive. The physics department faculty members have a terrific research record. It's also a very nurturing place, and I wanted to be part of the close personal interaction between faculty members and students that Bryn Mawr is known for. That was something I was not finding on the same level at research institutions."
It is not hard to see why Schulz was drawn to the College. As immersed as he is in the highly arcane and technical details of his discipline, there is something of the philosopher underneath his empirical exterior. In a specialty packed with data and driven by the search for quantitative evidence, Schulz seeks "an interpretive, qualitative understanding, which perhaps is just as exciting" as the models physics has provided to explain the world's workings.
"What I hope to accomplish is to better understand some of these great mysteries of the natural world," he says. "What was the physics of the earliest universe? What exactly are the building blocks? For the progress of science, I hope to contribute to making connections between string theory and observable physics. Despite the fact that string theory has been around for 25 years, there are some very basic things that we still don't really understand.
"If you've got a finite amount of time here on earth to learn the mysteries of the universe," Schulz adds, "it seems to me the most attractive pursuit is to seek answers to the most fundamental questions."
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