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For release at 10 a.m. EDT April 29, 2001
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Chronology of important cosmological research developments

  1. Arno Penzias and Robert Wilson of Bell Laboratories discover the existence of the cosmic microwave background radiation. They received the Nobel Prize in Physics for their discovery in 1978.


  2. The University of Chicago's Donald York and Princeton University's Jack Rogerson make the first galactic measurement of deuterium. Using the Copernicus satellite, they measure the deuterium abundance in the local interstellar medium by measuring the amount of ultraviolet light that was absorbed by deuterium in the starlight of nearby, hot, young stars.


  3. David Schramm, a graduate student at the California Institute of Technology, realizes that deuterium is a sensitive indicator of baryon density (the density of ordinary matter).


  4. The University of Chicago's David Schramm writes a seminal paper in which he argues that all the deuterium in the universe was made in the big bang. This means that the big bang must have produced at least as much deuterium as astronomers see today.

    Tom Adams, then a young Assistant Professor in Astronomy & Astrophysics at the University of Chicago, now at Los Alamos National Laboratory, outlines a technique for determining the abundance of deuterium in the big bang.


  5. The Massachusetts Institute of Technology's Alan Guth introduces the concept of cosmic inflation, which would become what is probably the most important idea in cosmology since the big bang itself.


  6. The idea that the largest structures in the universe grew from subatomic fuzz involved the University of Chicago's Michael Turner who attended a landmark conference, the Nuffield Workshop, organized by Cambridge University's Stephen Hawking. At the end of the two-week conference, four very different calculations arrived at the same amazing conclusion: if the universe inflated, then the largest structures grew up from the intrinsic fuzziness of the subatomic world. They also realized that the idea could be tested by measurements of the cosmic microwave background radiation, though experiments of the day were technologically unable to do so.


  7. The University of Chicago's Stephan Meyer and others on NASA's Cosmic Background Explorer (COBE) satellite team detect tiny fluctuations in the cosmic microwave background. These fluctuations relate to fluctuations in the density of matter in the early universe. These small variations in the distribution of matter bolster the big bang theory by revealing the seeds for all structure in the universe and opening the door to testing inflation.


  8. The University of California, San Diego's David Tytler and his then graduate student, Scott Burles, make the first definitive measurement of the deuterium abundance in a very distant and very primitive gas cloud with the 10-meter Keck Telescope. Since then, Tytler, Burles and others have measured the deuterium abundance in other pristine samples of cosmic gas and obtained similar values. Burles, who went on to a postdoctoral position at the University of Chicago, now is a staff scientist at Fermi National Accelerator Laboratory. Astrophysicists pin down the abundance of ordinary matter at 4 percent the total energy of the universe using theoretical calculations of big bang deuterium by the late David Schramm, Turner and others, and the Burles-Tytler measurement.

    David Schramm's last paper, written with the University of Chicago's Michael Turner, realized a career-long dream. Titled "BBN Enters the Precision Era," Schramm and Turner point out a critical test of the bang bang nucleosynthesis prediction for baryon density: comparing it with an independent determination based on the measurements of the cosmic microwave background radiation.


  9. An international team led by the California Institute of Technology's Andrew Lange announces the first results of its Balloon Observations of Millimetric Extragalactic Radiation and Geophysics (BOOMERANG) experiment. Flying high above Antarctica in late 1998 and early 1999, BOOMERANG obtained the first detailed images of the early universe. The images bolster inflation theory and show that the geometry of the universe is flat.

    An international team led by the University of California, Berkeley's Paul Richards announces results from the Millimeter Anisotropy Experiment Imaging Array (MAXIMA). Flying high above Texas during the summer of 1998 and 1999, MAXIMA collected data that confirmed BOOMERANG's findings and took the highest-resolution images yet of the cosmic microwave background.


  10. The NASA/National Science Foundation TopHat balloon experiment successfully completes a 27-day journey high above Antarctica. The international TopHat collaboration, which is led by the University of Chicago's Stephan Meyer, is expected to announce the results of its cosmic microwave background radiation experiment in 2002.

    The Collider Detector at Fermilab experiment begins. The University of Chicago's Henry Frisch and Melvyn Shochet and others begin searching for the neutralino, the leading candidate for dark matter.

    The University of Chicago's John Carlstrom and his research team announce the first data obtained from the Degree Angular Scale Interferometer experiment at the South Pole. The team's measurements of the cosmic microwave background radiation indicate that the density of baryons is 4.5 percent that of the total energy in the universe. The number matches with the one generated by measurements based on deuterium abundance.

    NASA's Microwave Anistropy Probe is scheduled for launch on June 30 to make further measurements of the cosmic microwave background radiation. Chicago's Stephan Meyer is a member of the MAP team.
Last modified at 01:29 PM CST on Friday, April 27, 2001.

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