Tophat and a Very Long Tail
by Duane Dunkerson
Before there were stars and galaxies there was the cosmic microwave
background radiation (CMBR). Tophat, a name for a unit of experimental
apparatus, sits atop a high-altitude (120,000 ft.) balloon. It
must be placed high in the sky above most of our interfering atmosphere.
Tophat may fly for days or weeks. As it goes along it spins and
"sees" a circle in the sky above the South Polar Region.
It is carried along above the South Pole because at the Pole there
are conditions supportive of less interference for the measurements.
The air is dry since there is less water vapor, warm objects giving
off radiation aren't as prevalent, and the Sun's own microwave
radiation is lessened by being no more than 23 degrees above the
horizon during the 6 month "day" and not seen for the
6 month "night".
What Tophat has at its crux are bolometers. The bolometers are
detectors that sense heat. Tophat's detectors are extremely sensitive.
In the circle that it is seeing, Tophat is to record variation
in the CMBR intensity in its circle in the sky. It is known that
the CMBR is not spread out evenly in the sky. Concentrations,
however slight, have been found. Tophat has a phenomenal accuracy
that enables astronomers to find out to what degree the concentrations
The universe, in its beginning, was hot and CMBR is the what's
left behind like the warmth near you after the wood-burning stove's
fire has gone out. In this case the stove (the universe) has expanded.
The stove's logs were not placed evenly one apart from the other.
They overlapped. The radiation, their warmth, is not evenly distributed
away from the stove.
Once the stars and galaxies came along, they did so in correlation
with where the radiation varied in distribution. The stars and
galaxies have their own distribution now as we see them. The CMBR
is older than the stars and galaxies. We can see differing times
in the universe - CMBR time and star-galaxy time. Noting the distribution
of CMBR as compared to the distribution of the stars and galaxies,
one can infer the age, size, and mass of the universe. Other fundamental
questions about the universe can be addressed such as will the
universe expand forever?
We can't find out the answers as quickly as we might like. Tophat
and its balloons can go up only once a year during favorable weather
conditions. Our slow data gathering is puny in time span against
the billions of years we use to characterize the universe. Yet
we may in a short time be able to speak confidently of scientific
matters in relation to a time scale far beyond our limits.