Lyman Page,
along with students and collaborators, measures the
spatial temperature variations in the cosmic microwave background
(CMB). The CMB, which pervades the universe,
is the thermal afterglow of the big bang. Detailed knowledge of
the
magnitude and pattern of the fluctuations in temperature
from spot to spot on the sky, or anisotropy, will help us
understand how
the universe evolved and how the observed structure, at sizes
ranging
from galaxies to superclusters of galaxies, was formed. From
precise
measurements of the CMB, one can also deduce many of the
cosmological parameters and the physics of the very early
universe.
For example we have been able to
determine the geometry and age of the universe,
the cosmic density of baryons, the cosmic density of dark matter,
and the Hubble constant.
Measuring the anisotropy is challenging, the variations in
temperature
are on the order of a few hundred thousandths of one degree
Celsius.
After nearly two decades of searching by groups at Princeton and
elsewhere, NASA's Cosmic Background Explorer (COBE) satellite
discovered
the long sought after fluctuations in 1992. This discovery
heralded a
new era in comprehending the cosmos. Page's work centers on
characterizing these fluctuations. The
research program is
focused on
developing and building precision radiometers operable over a
range of
frequencies. Additionally, a considerable effort is spent on
developing new techniques for analyzing anisotropy data.
This is an extremely exciting time for cosmology. The
experimental
tools and techniques, coupled with theory, have developed to the
point
were we can probe the physics of the infant universe in wonderful
detail. There are many cosmologists at Princeton and a number
work on
CMB related projects. On the theoretical front, there
are Uros Seljak, Paul Steinhardt, Jim Peebles, and David Spergel.
On the experimental front, there are Joe Fowler, Norm Jarosik,
Lyman Page, and Suzanne Staggs.
The Wilkinson Microwave Anisotropy Probe. Princeton is heavily
involved
in all aspects of the WMAP satellite. The project was a
partnership
with NASA/GSFC with collaborators at Chicago, UBC, Brown, and
UCLA.
Much of the instrument was designed and built at
Princeton and the Princeton team played a large role in the data
analysis. In the first
data release (February 2003) we
presented
the most accurate and precise measurements of the CMB anisotropy
to date. WMAP will operate through 2005. The analysis is in full
swing.
The satellite is named in honor of Prof. Wilkinson, a leader in
experimental cosmology and a faculty member in the Physics
Department until his death in 2002.
The
Atacama Cosmology Telescope. WMAP continues to map
the anisotropy with an angular resolution of 0.2 degrees.
There is a wealth of cosmological information that may be
obtained with measurements at finer angular scales.
For example, we can understand how the first cosmic structures
formed through the Ostriker-Vishniac and Sunyaev-Zel'dovich
effects. From the growth of structure and the WMAP data, we
can determine the neutrino mass and the possibly the equation
of state of the dark energy or quintessence. The Princeton group
is
a leading member of a large collaboration to build a 6m telescope
in Chile with thousands of detectors and an angular resolution of
0.03 degrees.
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