Assistant Professor of Cosmology
Rachel Bean | Cornell University
Exploring Cosmic Origins
Rachel Bean landed on the cosmology scene just in time for one of its most exciting eras in a long, long time - in about 13.73 billion years.
With new data cascading in, Bean is sorting out the still-durable theories of the origin of the cosmos from those that don't hold up.
A few years ago, Bean arrived for post-doctoral work at Princeton during a time of big developments in cosmology thanks to the WMAP (Wilkinson Microwave Anisotropy Probe) satellite. She was part of the NASA team that has produced the most detailed full-sky maps of the early universe. Suddenly, rich observations made by the satellite "way out beyond the moon" have erased old doubts about how the universe behaved in the first trillionths of a second after it was created.
Since then, the new data has transformed astronomy, challenging anyone in the business of cosmological theory. "The new level of precision is exquisite," Bean said.
Bean says her own research bridges two camps, between theory and those who mainly observe. "I guess I am a theorist who isn't frightened by data," she said.
In her research at the Cornell Space Sciences Building, she is building simulations of how the universe came into being and grew to what we see today. She builds statistical models of what might have happened and calculates how probable it is that the models are correct.
"For example, we are looking at how big the universe was at different stages in its life, how many galaxies it contained, and how they are arranged," she said.
What put her at Princeton at the right moment was a bit unconventional. She was born in Leyland, in Lancashire, England; studied physics at Cambridge; and worked in Management Consultancy until, she recalls, "I realized I loved physics more than I had realized." She entered Imperial College in London for a Ph.D. in cosmology. Then, after three years at Princeton, she joined the astronomy faculty at Cornell.
Today, she is a top expert on the origin of dark energy and dark matter - "dark" because it is invisible to telescopes - which together make up most of the stuff of the universe.
At the outset, the newborn universe, she says, was a trillion trillion times smaller than an atom. Its energy level was a trillion times larger than what can be measured in a particle accelerator. "The universe can be thought of as the ultimate particle accelerator," she says, "giving us insights into the nature of physics that we would never be able to attain terrestrially."
In the last century, it seemed the cosmologists had things down pat, Bean says. Edwin Hubble's observations of the expanding universe were explained by Einstein's Theory of General Relativity, linking the expansion to the amount and types of matter, while the Standard Model of particle physics told us how normal matter - from chemicals to stars - is made up of quantum particles.
Now, Bean says, "It's clear that we still know embarrassingly little about the universe. The ignorance is on a truly cosmic scale."
It's her goal to learn more, working from current observations of cosmic microwave background (CMB) radiation, the light left over from the Big Bang and still traveling after 13.7 billion years.
That may tell us not only where it all came from but where it's going next.
Education Goals:
Rachel Bean plans to continue her outreach and education efforts that have included public talks and a series of illustrated videos to introduce cosmology to nonscientists. One set of videos is at:
http://sandstone5.cit.cornell.edu/Requester/r/roomMain/Cosmophys
She will develop a new freshman-level course on critical thinking applied to cosmology. "People often see physics as a fait accompli. It's easy to think of Newton's and Kepler's laws as irrefutable, and overlook the process required to really question a theory's validity." Her course for science and engineering majors will encourage students to criticize theory, starting with Copernicus's heliocentric (sun centered) cosmology to variants of Newton and Kepler, and to debate merits of current theory about dark matter, dark energy and black holes at the center of galaxies.
