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Nobel Laureate Wilczek Speaks On Strangeness of the Universe

By Kelley Rivoire

NEWS EDITOR

MIT Professor and 2004 Nobel Laureate in Physics Frank Wilczek spoke to a packed audience at Kresge Auditorium yesterday in a talk entitled “The Universe in a Strange Place.”

Dressed characteristically in a black tee shirt and jacket, Wilczek spoke of strange, yet beautiful physics of the world as understood by physicists today, and he suggested ways for physicists to continue their struggle to understand such mysteries as dark matter and dark energy.

Mass as “a music of the void”

Much of the modern physics understood today is “strange in many ways,” Wilczek said. He suggested, however, that insight can be gained by disposing of the traditional notions of particles and instead considering wave patterns, and even the tones of musical instruments.

“The equations of musical instruments are exactly the equations one encounters when describing what happens inside hydrogen atoms according to the modern quantum theory,” Wilczek said.

This musical analogy can be extended to mass as well, Wilczek said. Mass perplexes physicists, he said, since nucleons with mass such as protons and neutrons are composed of nearly massless quarks and massless gluons.

Rewriting Einstein’s fundamental equation as mass being equal to energy divided by the square of the speed of light, however, “suggests the possibility of explaining mass purely in terms of energy,” and was the form in which Einstein initially wrote his famous equation, Wilczek said.

According to quantum field theory, “what appears to us as empty space is in reality a wildly dynamical medium” with short-lived “virtual particles” created as a consequence of an uncertainty in energy and time interacting with real particles.

The “different particles we observe correspond to different vibration patterns in this dynamical void,” and stable particles “are just vibration patterns that have a particularly long lifetime,” he said.

Furthermore, expressing energy in terms of frequency generates a unique mapping between a mass and an associated frequency. This suggests the masses of particles “are the tones, the frequencies of these vibration patterns in the dynamical void,” Wilczek said.

“There’s a music of the void” in the table of particle masses, he said.

Experiment shows quarks, gluons

Wilczek spoke about experiments conducted at CERN European Laboratory for Particle Physics that verify the quark and gluon model.

The principle of asymtotic freedom states that “radiation events that significantly change the overall flow of energy and momentum are very rare,” while events that do not change the flow of energy and momentum are more common, Wilczek said.

A picture showing two jets, groups of particles moving in the same direction, emerging from a collision of particles, indicates quarks and anti-quarks, whereas a picture with three jets emerging indicates the presence of gluons, which perturb the energy and momentum flows, as well.

By looking at the probability distributions of the numbers of jets, their angles, and energies as a function of the initial annihilation energy, physicists can rigorously test their theories, and have been able to verify gluons and quarks as a “complete description,” Wilczek said.

In addition, the mere fact “that you don’t get the same thing coming out every time even though you put the time thing in” reflects the probabilistic nature of quantum mechanics, he said.

“We still have a lot to learn”

Wilczek discussed not only the mysterious physics now understood, but also the phenomena whose mysteries have yet to be decoded, as well as ways that physicists might begin to understand these phenomena.

First and foremost in the realm of the explained is cosmology, a field in which “we don’t know what’s going on,” Wilczek said.

Astronomers have calculated that only five percent of matter in the universe is the ordinary matter that we understand. Twenty-five percent is “dark matter,” something we can only detect by its gravitational influence on ordinary matter, and which exists in clumps. The remaining seventy percent is “dark energy,” which is evenly spread, as if it were “an intrinsic property of space and time,” Wilczek said. The dark energy exerts a negative pressure, and is the reason for the accelerating expansion of the universe, Wilczek said.

In order to attack such problems as dark energy, Wilczek suggested that physicists”try to improve the equations of the part of physics we know,” and “extend the amount of symmetry.” Symmetric theories developed so far provide possible explanations for dark matter, Wilczek said.

Wilczek’s talk led up to three so-called lessons he has gleaned from physics. Firstly, “if we work to understand, then we can understand,” as evidenced by the studies of the strong interaction. Secondly, “the part of the world we understand is by any standard strange, and I think quite beautiful.” Finally, Wilczek said, “We still have a lot to learn.”