page 6 The Signal September 20, 2017 page 6 The Signal September 20, 2017

Physics colloquium kicks off string theory seminar series

Left: Kalb describes microscopic matter. Right: String theory is the only modern theory that quantifies gravity.

By Heidi Cho Nation & World Editor

A sunny Friday afternoon was juxtaposed with a discussion of string theory on Friday, Sept. 15, in a physics colloquium. Michael Kalb, an adjunct physics professor at the College, gave the first presentation of a seminar series with the working title “String Theory Seminar.” “String theory is the theory of the universe,” Kalb said. “It makes the assumption that most microscopic matter are filaments.” According to string theory, these filaments have a specified length, and intersect each moment of time at a specific point. Most objects in the world can be visually represented by a world-line. That line would have a path through planes of time, like a string threaded through a pile

of printer paper, and each plane or paper would be like a coordinate graph to plot the location of the object. It is only a visual aid, but it still demonstrates how string theory can graph the universe. It is also the only modern theory that manages to quantify gravity, according to Kalb. Since strings can vibrate, gravity becomes quantifiable because all strings can vibrate at the mode of a graviton — a hypothetical particle used to measure gravity in theoretical quantum physics. This is remarkable because when it comes to creating an unifying theory, gravity is the problem child out of the four fundamental forces of nature. Kalb remarked that it refuses to quantify, and it doesn’t cooperate, refusing to be wrangled into the same formula as the other forces.

Kalb went on to explain the thought behind the search for a unifying theory. 3.8 billion years ago everything was so close together, so hot, that there was only space enough for one force. That one force then split into the four forces sometime when the universe expanded and cooled down. Kalb admitted there was no firsthand evidence that the four forces were ever once one force just as unabashedly as he admitted string theory is not yet a mature theory, and not yet experimentally verified. Due to the theory’s infancy, it is rare for it to be academically offered to undergraduates who appreciated the series as “a window into the state of modern theoretical physics,” according to Chris Lovenduski, a sophomore physics major who attended the seminar.

Kalb listed nine possible predictions string theory could make. One problematic contingency was that there would have to be either 10 or 26 spatial dimensions for string theory to be plausible. Another contender for what could eventually lead to a unifying theory, the standard model, is not flawless either. It has approximately 20 unidentified parameters, while string theory has one identified parameter of minimum string length. With those unidentified parameters, Kalb joked that four of them could be an elephant, and with the fifth parameter, you can twist the trunk of the elephant, emphasizing how drastically the theory could change due to the missing factors. Though neither theory is close to unifying all of physical phenomena,

Kim Iannarone / Photo Editor

there is a pattern with ground breaking theories and the important scientists, like James Clerk Maxwell, Albert Einstein, or Isaac Newton, that make them. These scientists unite together seemingly disparate parts of science from clouds to black holes and allow for accurate predictions of the universe by building on top of each other’s theories. Science is an ongoing process, and the most important takeaway from this seminar for Lovenduski was that “the unification of all physical observations is not some defined moment.” “String theory might be the next step in revising existing theories to fit more physical observations,” Lovenduski said, “but if proven correct, it will not be the end of the line for theoretical physicists.”

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