Smithsonian Cosmology Gallery Would Showcase Seminal Work of Richards & Smoot

May 2, 1997

By Jeffery Kahn,

Though it does not yet rival the public interest in UFOs, cosmology -- the study of the origin, evolution, and structure of the universe -- increasingly engages the public imagination. Aware of this phenomenon, the Smithsonian Institution's National Air and Space Museum currently is contemplating adding a new gallery devoted to this field of exploration.

Since its opening in 1976, the museum has become a favorite of visitors to the nation's capital. Its most famous exhibits include the original 1903 Wright Brothers' airplane, Charles Lindbergh's Spirit of St. Louis, the Apollo 11 command module from the first manned lunar landing mission, and rocks retrieved from the moon.

Dave DeVorkin, the museum's curator for the history of astronomy, is spearheading the proposal to extend the museum to include the human quest to investigate and understand the cosmos. Berkeley Lab has a significant role in this story, says DeVorkin.

At this stage, says DeVorkin, "I am collecting objects that are worthy of permanent preservation in the national collection, objects that have played a prominent role in the history of astronomy. They would be displayed in a proposed new gallery (an extension to the museum) to be constructed here. This gallery would explore cosmology back to the beginning of human curiosity. Its working title is "`Explore the Universe.'"

If "Explore the Universe" is built, it would open to the public around the year 2001. Half of the 5,000-square-foot gallery would be devoted to contemporary cosmology.

In recent months, DeVorkin has contacted the Physics Division's George Smoot and the Material Sciences Division's Paul Richards. Both Smoot and Richards led scientific teams that made seminal discoveries about the early universe. Both have provided instruments and apparatus that now have become part of the Smithsonian's permanent national collection of historic objects.

The two scientists have made their mark studying the cosmic microwave background, the remnant radiation from the Big Bang that suffuses space.

Smoot's most significant contribution is well known. On April 23, 1992 at an American Physical Society meeting in Washington, D.C., he announced the discovery of fossil relics from the primeval explosion that began the universe: 15- billion-year-old primordial seeds that grew into the galaxies and superclusters of galaxies evident today.

The discovery was made through the use of exquisitely sensitive microwave receivers created for NASA's Cosmic Background Explorer (COBE) satellite. The receivers detected regions of space 100 million light years across and larger with temperature differences of a hundred-thousandth of a degree. As Smoot explained, "These small variations are the imprints of tiny ripples in the fabric of space-time put there by the primeval explosion process. Over billions of years, gravity magnified these ripples into galaxies, clusters of galaxies, and the great voids of space."

DeVorkin chose two microwave receivers -- known as Differential Microwave Radiometers -- to make a part of the Smithsonian's permanent collection. One was the prototype for COBE

and the other, flown on a U2 aircraft in the 1970s, was used to discover that the motion of our own galaxy through space exceeds one million miles per hour (relative to the distant matter in the Universe).

Paul Richards led a group that, in the 1970s, performed balloon-borne experiments that provided compelling evidence that the cosmic microwave background radiation is a blackbody spectrum.

When something is hot, it emits electromagnetic radiation. For every temperature, there is a unique and corresponding distribution of wavelengths and frequencies known as the blackbody spectrum, even for something as hot as the Big Bang.

Says Richards, "At a time when there was significant uncertainty, our data showed that the early universe was a blackbody. It documented that the universe was not a steady state (in which matter is continuously created and formed into new galaxies.) Instead, this was the strongest possible evidence for the Big Bang origin of the radiation."

Richards recalls that it was Nobel laureate Charles Townes who first involved him in astrophysics. Townes was always interested in the big questions of the day and was aware that the existing measurements of the spectrum of the background radiation showed large deviations from a blackbody spectrum.

Says Richards, "I was a condensed matter physicist in the Inorganic Materials Research Division at the Lab with an expertise in using infrared spectroscopy to probe the properties of matter. Townes approached me to say that he believed I had the best technology for measuring the temperature of higher frequency cosmic microwave background. He guessed, correctly it turned out, that we already had the building blocks to do this science."

Richards joined with two graduate students, John Woody and John Mather (later chief scientist for COBE). By 1974, they had built an apparatus that consisted of an antenna, spectrometer, and detector, all cooled by liquid helium to a temperature below 3 Kelvin. Beginning in 1973, this balloon-borne apparatus made a number of flights. For the next15 years -- up until the time of COBE -- the results of these flights provided the best evidence available that the background radiation indeed was a blackbody.

DeVorkin reports that elements of what came to be known as the Woody/Richards experiment now have joined the Smithsonian's permanent collection.

Says DeVorkin, "It's too early to say whether we will receive approval from the Smithsonian's director to create the `Explore the Universe' gallery. If we receive the go-ahead, then we still must secure funding to build it. However, even if the new gallery is not built, these objects will remain part of the national collection and will be available for future exhibit both here and for loan to other museums."

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