VT College of Science Magazine Annual 2014 | Page 17

“I didn’t have a single female professor in my undergraduate courses, for example, and I had no real female role models in graduate
school, which means it was impossible as a young woman to look
up to someone else who already had the kind of career you wanted
and who was successful. They didn’t exist, so entering the field your
gender really is part of the question, ‘Can I do this? Can I be really
successful and do what I want to do?’ And the answer is, yes.”

says those extra dimensions
that may exist could actually be very small and sort
of wrapped up around our
existing universe at a scale
that’s too small for us to
detect.”

After earning a doctoral degree in mathematical physics, she spent
the next five years doing postdoctoral work at a who’s who of universities, including the University of Pennsylvania, the Institute for
Advanced Study at Princeton, and at Harvard University’s Center for
the Fundamental Laws of Nature, before arriving at Virginia Tech in
2013 with her husband, James Gray, also a physicist. As a post-doc
she worked in high-energy particle physics and string theory, asking the questions that have been asked by others for decades – what
particles exist in the universe? What forces govern their behavior?
How do you mathematically describe the framework that holds this
all together and how do you test it in lab to decide if it’s correct?

The classic example of this is to imagine looking at a wire from very far away.
From a distance it looks one dimensional, like a
line. But up close you can see it has a thickness, a radius, so the two
dimensions of that wire, its length and width, have very different properties.

“It’s an exciting time,” she said of string theory. “This beautiful mathematical formulism for trying to describe all the forces and particles
that we see in nature is a lovely idea that’s been around for about

‘Can I do this? Can I be really
successful and do what I want
to do?’ And the answer is, yes.”
20 years and is the realization of what’s been called the Holy Grail
of modern physics. It is a question first posed by [Albert] Einstein –
could you put together the forces we see in nature like gravity, electromagnetism, and nuclear forces; could you put this all together
into one theoretical framework? Einstein spent the majority of his
working life after discovering relativity trying to answer this question, which he wasn’t able to do. So string theory is formally the
only working quantum theory of gravity we have that can, in principle, put all these forces together into one framework.
“The problem is that, well, there are a couple of problems,” she
admitted. “First, we haven’t been able to come up with an experimental way to verify the theory. Second is that it predicts the
universe has more than the four dimensions of space and time that
we see around us (three dimensions of space and one of time). At
first pass that sounds like a deal-breaker. However, string theory

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“What I actually work on is trying to decide if the universe has extra
dimensions and if they could be wrapped up in different ways and
how that would change the laws of physics. The nice thing is the
shape of these extra dimensions in string theory have incredible
predictive power, so if you try to say the extra dimension looks like
‘x’, then that changes the mass of the electron in the theory that you
would write down; it changes how quarks couple together differently; the profile of how the universe expanded.
“The main question is this: does there exist a way to wrap up these
dimensions so that you get the universe you see, and can you test
that in a lab? I’m optimistic the answer is yes,” she said. “At least we
can decide if this is a good idea or not.”
What happens if it turns out string theory is not a good model?
“Well, then, we’ve learned something useful. In modern particle
physics the lag time between theory and experiments has been getting longer simply because the experiments are bigger and harder
to make. The Higgs boson was discovered two years ago, 50 years
after Higgs suggested such a particle should exist. We know a lot
about how particles interact, so finding new properties is harder
and harder. In principle, string theory could be shown to be correct
or incorrect. If it’s incorrect, that would actually be very exciting in
its own right because it would tell us that a lot of the assumptions
we’ve been making for the last 20 years are wrong and we need to
look in brand new areas.”
Finding the answers to these questions will take time, resources,
and scholars who possess the capacity to think big. Finding those
scholars may require looking in brand new areas too, maybe even
the local planetarium.

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