The universe “sings.” By studying the vibrations that produce that song, scientists have discovered what cosmologist Charles Lineweaver has called “the oldest music in the universe” (Cole, L.A. Times).
The music originated when the universe was in its infancy, about 400,000 years after the big bang (the cosmic explosion that marked the beginning of the universe according to the big bang theory). At that time, nothing existed but pure light and some subatomic particles. The light and “matter fluid,” as physicists call it, sloshed in and out of gravity wells, where compression of the “liquid light” set up sound waves, producing “the oldest music in the universe.”
The early universe was like a dense fog because photons (energy packets of light) could not travel far without hitting electrons. But by the age of 400,000 years, the universe had cooled enough so that electrons and protons could combine to form atoms (and eventually galaxies, stars, planets, and so on). At that point, the universe became transparent, and photons began their flight through space, still reaching our telescopes today, nearly 14 billion years later.
That early light, or radiation, “sings” the story of the young universe. Scientists can capture, graph, and read that song (like reading a music score) by studying cosmic background radiation, a subtly complex hiss of microwave radiation pervading the universe–the echoes of the big bang.
The most extensive information about cosmic microwave background radiation to date has come from the Cosmic Background Imager, a special-purpose telescope comprising thirteen separate antennas, each operating in ten frequency channels. Caltech scientists designed the Cosmic Background Imager, built it, and moved it to its present location at Llano de Chajnantor, a high plateau in the Chilean Andes.
Graphic depictions of microwave data, mostly wiggly up-and-down lines, portray the music of the universe at the age of 400,000 years. The wiggly lines visually represent the movements of microwaves, which were originally set in motion by primordial vibrating sources. In those graphs, according to a Caltech news release, “we see a series of peaks and valleys, where the peaks are successive harmonics of a fundamental ‘tone'” (Caltech).
By analyzing the primordial song, scientists can learn more about the early universe itself. The sonic patterns that emanated from the early sloshing particles left a continuing record of the young universe: its birth, its shape, and its matter. The study of those patterns is based on the familiar principle that a unique sound is created by the unique shape and material of a sounding body: “the sounds coming from the early universe depend directly on the density of matter, and the shape of the cosmos itself” (Cole).
In a series of studies headed by Caltech’s Andrew Lange, Anthony Readhead, and others, analyses of cosmic microwave background radiation have confirmed the conventional theory of the big bang: the universe was born nearly 14 billion years ago, is geometrically “flat,” and is expanding. Eventually such studies may also help in understanding the newly discovered and mysterious “dark energy” in the universe.
Scientists have theorized that gases of the early universe contained tiny temperature variations caused by sound waves in the rapidly expanding fireball. “The fireball was, in effect, ringing like a bell. The ‘notes’ on which the early fireball was singing give a direct way to calculate cosmological parameters like the geometry of space-time, the density of the universe, and its rate of expansion” (Overbye, New York Times News Service).
The most fundamental of those cosmic notes has a frequency (rate of vibration) that outlines the geometry of space-time. The next two higher notes on the cosmic scale relate to each other in a way that helps scientists gauge the densities of ordinary and dark matter in the universe. The Cosmic Background Imager “is now starting to reveal the higher ‘overtones'” (Astrowatch).
Scientists should soon discover even more notes in the cosmic scale through further experiments, such as the Planck Surveyor, a spacecraft scheduled for launching in 2008. It will carry low and high frequency instruments to record the vibrations of the cosmic microwave background radiation, the oldest music in the universe.
Astrowatch, “Cosmic Background Imager Confirms Flat Universe Observations,” http://cerncourier.com/main/article/42/6/13
Caltech Press Release, Oct. 7, 2004, “CBI Reveals Motion in the Remotest Seeds of Galaxy Clusters in the Very Early Universe,” http://mr.caltech.edu/media/Press_Releases/PR12595.html
K.C. Cole, “The Cosmos Was Alive with the Sound of Matter,” Los Angeles Times, May 11, 2000, B2
Cosmic Background Imager, May 7, 2007, http://www.astro.caltech.edu/~tip/CBI
Darryl Lyman, Music of the Universe, http://members.sibeliusmusic.com/darryllyman
Dennis Overbye, New York Times News Service, “Astronomers View Universe at 300,000 Years Old,” Riverside (Calif.) Press-Enterprise, May 26, 2002, A23
