Guide to the Universe-Dept of Physics - Carnegie Mellon University

Saturday, December 1, 2012

Guide to the Universe

Simulations developed by the McWilliams Center allow researchers to visualize the evolution of elements within the universe. This image shows the gas that surrounds a quasar. Image: Yu Feng.
Simulations developed by the McWilliams Center allow researchers to visualize the evolution of elements within the universe. This image shows the gas that surrounds a quasar. Image: Yu Feng.

Just as early cartographers struggled to map the terrain of undiscovered lands on Earth, modern day cosmologists face a similar challenge as they try to map the universe—something they can’t physically explore. While the invention of tools like the sextant and compass helped terrestrial mapmakers, new technologies like the latest generation telescopes and the largest supercomputers are allowing cosmologists to map the far reaches of space without leaving the comforts of Earth.  The light that is given off by galaxies, quasars, supernovas and stars help cosmologists draw maps of the visible universe. How that light behaves in space also gives researchers clues to understanding what is happening in the vast areas that are dark. In fact, most of the universe—96 percent of it—is made of dark energy and dark matter that can’t be seen directly.

Mapping the universe, both the visible and invisible parts, is a huge undertaking. No one university, let alone one person, could map the universe. Large collaborations that often involve researchers from laboratories and universities around the world are key to creating detailed cosmological maps.

“In general, there are things that can’t be done with one or two people working alone. When you want to answer a question as big as ‘what is the universe made of?’ you need these large collaborations,” said physicist Rupert Croft. “The future of cosmology is doing these large surveys of the universe. The strengths of CMU, things like theory, observation, computer science and statistics, are well oriented to this type of astrophysics.”

Carnegie Mellon University’s Bruce and Astrid McWilliams Center for Cosmology has been growing to meet these challenges. Since its inception in 2008, the center has hired Assistant Professors Shirley Ho, Rachel Mandelbaum and Hy Trac, three of the most promising young cosmologists in the field, to complement the work of the center’s other high-profile faculty, including Associate Professors Croft and Tiziana Di Matteo and Professor Jeffrey Peterson. The center also has recruited a number of skilled graduate students and postdoctoral researchers. These scientists are taking leading roles in multiple prominent international cosmology collaborations, including the Sloan Digital Sky Survey III (SDSS-III), the Large Synoptic Survey Telescope (LSST), the Giant MetreWave Radio Telescope, the Hyper Suprime-Cam (HSC) survey and the Atacama Cosmology Telescope (ACT). Their work has been highlighted recently in the December issue of Science Connection.