January 21, 1999
Vol. 18 No. 8

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    Pritzker symposium to look more closely at inflationary theory

    By Steve Koppes
    News Office

    The inflation theory proposes that the universe expanded extremely rapidly soon after the big bang and effectively explains a number of important questions the big bang theory alone has been unable to answer. Inflation theory also meshes particle physics with astrophysics, inner space with outer space, said Michael Turner, symposium co-chair and Chair of Astronomy & Astrophysics at Chicago.

    “It holds that the largest structures in the universe, from galaxies to great walls made of galaxies, originated as quantum fluctuations on the subatomic scale.”

    Some of the world’s top experts in cosmology will gather Jan. 29 to Feb. 3 for the Pritzker Symposium on the Status of Inflationary Cosmology at the University to discuss how well inflationary theory is holding up against new observations.

    The symposium, along with the opening of the new Pritzker Gallery of Cosmology at the Adler Planetarium and Astronomy Museum, marks the official beginning of the city of Chicago’s Project Millennium, a yearlong program to celebrate and reflect upon the millennium. Symposium sponsors are the University, Fermi National Accelerator Laboratory and the Adler Planetarium.

    “Nicholas Pritzker, an avid cosmologist, approached the Adler Planetarium about a gallery that would trace our understanding of the universe from Copernicus to inflation,” said Evalyn Gates, director of astronomy at Adler Planetarium. “As a result, the Adler created a gallery that even includes pages from the notebook of Alan Guth, one of the inventors of inflation.”

    The inflation theory has been around for more than 15 years, but only in the past few years have astronomers collected the first observational data in its support, said Rocky Kolb, Professor in Astronomy & Astrophysics and symposium co-chair.

    Inflation predicts a pattern of temperature differences in the cosmic microwave background radiation, the big bang’s afterglow. According to the theory, some regions of the sky should have slightly higher temperatures than other regions of the sky, and measurements made by Chicago scientists and others are beginning to bear these predictions out, said Kolb.

    Inflation also predicts that the total amount of matter and energy in the universe adds up to the critical density, which would mean the universe is flat like a piece of paper instead of curved like a sphere.

    “Just this year, we have the first evidence that this is true, and amazingly, that 60 percent of the critical density is in the form of a mysterious dark energy that is causing the expansion of the universe to speed up rather than slow down,” Turner said. “We are excited to have at long last found the ‘missing energy’ that brings the total to the critical density. Now we have to figure out what it is!”

    Astronomers are expecting to receive an avalanche of high-quality data during the coming years that will help them to confirm or refute inflation theory and possibly begin to probe the earliest moments of creation, said symposium co-chair Josh Frieman, Fermilab Scientist and Professor in Astronomy & Astrophysics.

    Crucial to testing inflation is the study of millionth-of-a-degree variations in the temperature of the cosmic microwave background in different directions. Some of the data will come from ongoing experiments being conducted at the University’s Center for Astrophysical Research in Antarctica and from balloon experiments at the South Pole that involve Chicago scientists.

    Further data will come from two satellites: the Microwave Anisotropy Probe that the National Aeronautics and Space Administration will launch in 2000, again with Chicago’s involvement, and the Planck Surveyor, which the European Space Agency will launch in 2007.

    The Sloan Digital Sky Survey also will be important in tying down the validity of inflation, said Kolb. The survey is an international collaboration of scientists and engineers, including Frieman and others at the University and Fermilab, to catalog the positions and brightness levels of more than 100 million galaxies.

    The survey’s objective is to map one quarter of the sky and create a systematic, three-dimensional picture of the universe 100 times larger than what was previously available.

    The NASA and European satellites, on the other hand, will study the large-scale structure of the universe but at a much earlier and simpler time. The cosmic microwave background is in effect a snapshot of the Universe when it was 300,000 years old, long before stars and galaxies existed.

    “We’re hoping that in the next few years these two different maps will complement one another and provide a consistent picture for the large-scale distribution of mass in the universe, and tell us about what conditions were like in the very early universe, thereby testing inflation,” Frieman said.

    “Inflation predicts certain patterns of fluctuations in the density of the universe, and that should be imprinted both in the microwave background about 100,000 years after the big bang and also in the large-scale distribution of galaxies, which was laid down more recently.”

    The symposium is scheduled from Jan. 29 to 31 and will consist of talks by 14 of the most distinguished cosmologists in the world, summarizing the current status of inflation theory.

    Among the astronomers making presentations at the symposium will be the three men who developed the inflation theory: Alan Guth, Massachusetts Institute of Technology; Andrei Linde, Stanford University; and Paul Steinhardt, Princeton University. Also presenting will be two scientists who made fundamental contributions to big bang theory: Sir Martin Rees of Cambridge University and P.J.E. Peebles of Princeton University. Another presenter will be Stephen Hawking, Cambridge University’s Lucasian professor of Mathematics, a position once held by Isaac Newton.

    Hawking will give a public lecture in addition to his scientific presentation to symposium participants. The public lecture, “The Universe in a Nutshell,” will begin at 8 p.m. Jan. 29 in the Arie Crown Theater at McCormick Place. The lecture is sponsored by the Adler Planetarium and the Pritzker Foundation. For ticket information, call (312) 559-1212. The public also is invited to visit the newly opened Pritzker Gallery at the Adler Planetarium. For information, call (312) 322-0304.

    Following the symposium will be a workshop from Feb. 1 to 3 that will be attended by more than 200 experts from around the world.

    “I tell my undergraduates at Chicago that every educated person should have some idea of the origin, age and size of the universe,” Kolb said. “We all live in the universe. It’s not just a matter of study for the experts who are coming to this meeting or the few hundred people in the world who call themselves cosmologists. I tell the students, ‘It’s your universe, too.’”