CBI samples the temperature variations of the faint microwave emissions across a section of sky. Angular resolution is 7 arc min, about 4 times smaller than the full moon. Scientists plot the variations in intensity of the temperature as seen below. The CBI map is similar to maps produced by other teams, except that it has significantly higher resolution. In itself, these maps do not tell the whole story.
Theoretical work on the CMB demands that temperature plots can be reinterpreted in a mathematical way known as a "spherical harmonic expansion." After some math and computational firepower, the plots in fig. 3 can be produced.
The early universe at the moment the CMB was created was a gas of protons, neutrons and photons at a temperature of about 4000 degrees.
Disturbances in this gas propagated much like sound waves. The math of acoustics says that these disturbances peak at a fundamental frequency, and then at even and odd harmonics. This is analagous to waves that are made when a rope is whipped up and down. The frequencies of these peaks are represented by the quantity "l" along the x-axis in both plots.
One of the central questions in the field of cosmology is the "shape" of our
universe. The geometry of the universe depends on the energy density of the
universe, designated by Omega. There are three quantities that contribute
to Omega--ordinary matter, dark matter and dark energy. This state of affairs
is summed up by the equation:
dark energy + ordinary matter + dark matter = total
energy density of the universe
The unique high-resolution CBI observations provided independent evidence for a flat universe in which Omega (total) is made up of 5% normal matter, 35% dark matter and 60% dark energy. The term "dark energy" is also sometimes referred to as the "cosmological constant," a concept originally proposed by Einstein in 1917.
The CBI telescope is the first one sensitive enough to sample the CMB with enough angular resolution to discern the clumps of matter which in time eventually evolved to become the clusters of galaxies we see today. Below is a time line in real years for the approximate age of the universe. The second time line is the age of the universe expressed in terms of the age of a human. On that scale the CMB would be only 2.5 hours old.
0 / conception
300,000 yrs/ 2.5 hrs old (CMB radiation)
1 billion yrs / 1 yr old
14 billion yrs / 14 yrs old (clusters of galaxies)
Return to NSF PR 02-41 images.