Parallel Worlds Read Free

special
point of relative stability near Earth). From this vantage point, the satellite
always points away from the Sun, Earth, and Moon and hence has a totally
unobstructed view of the universe. It completely scans the entire sky every six
months.
    Its
instrumentation is state-of-the-art. With its powerful sensors, it can detect
the faint microwave radiation left over from the big bang that bathes the
universe, but is largely absorbed by our atmosphere. The aluminum-composite
satellite measures 3.8 meters by 5 meters (about 11.4 feet by 15 feet) and
weighs 840 kilograms (1,850 pounds). It has two back-to-back telescopes that
focus the microwave radiation from the surrounding sky, and eventually it
radios the data back to Earth. It is powered by just 419 watts of electricity
(the power of five ordinary lightbulbs). Sitting a million miles from Earth,
the WMAP satellite is well above Earth's atmospheric disturbances, which can
mask the faint microwave background, and it is able to get continuous readings
of the entire sky.
    The satellite
completed its first observation of the full sky in April 2002. Six months
later, the second full sky observation was made. Today, the WMAP satellite has
given us the most comprehensive, detailed map of this radiation ever produced.
The background microwave radiation the WMAP detected was first predicted by
George Gamow and his group in i948, who also noted that this radiation has a
temperature associated with it. The WMAP measured this temperature to be just
above absolute zero, or between 2.7249 to 2.7251 degrees Kelvin.
    To the unaided
eye, the WMAP map of the sky looks rather uninteresting; it is just a
collection of random dots. However, this collection of dots has driven some
astronomers almost to tears, for they represent fluctuations or irregularities
in the original, fiery cataclysm of the big bang shortly after the universe
was created. These tiny fluctuations are like "seeds" that have since
expanded enormously as the universe itself exploded outward. Today, these tiny
seeds have blossomed into the galactic clusters and galaxies we see lighting up
the heavens. In other words, our own Milky Way galaxy and all the galactic
clusters we see around us were once one of these tiny fluctuations. By
measuring the distribution of these fluctuations, we see the origin of the
galactic clusters, like dots painted on the cosmic tapestry that hangs over the
night sky.
    Today, the
volume of astronomical data is outpacing scientists' theories. In fact, I
would argue that we are entering a golden age of cosmology. (As impressive as
the WMAP satellite is, it will likely be
    dwarfed by the
Planck satellite, which the Europeans are launching in 2007; the Planck will
give astronomers even more detailed pictures of this microwave background
radiation.) Cosmology today is finally coming of age, emerging from the
shadows of science after languishing for years in a morass of speculation and
wild conjecture. Historically, cos- mologists have suffered from a slightly
unsavory reputation. The passion with which they proposed grandiose theories
of the universe was matched only by the stunning poverty of their data. As
Nobel laureate Lev Landau used to quip, "cosmologists are often in error
but never in doubt." The sciences have an old adage: "There's
speculation, then there's more speculation, and then there's cosmology."
    As a physics
major at Harvard in the late 1960s, I briefly toyed with the possibility of
studying cosmology. Since childhood, I've always had a fascination with the
origin of the universe. However, a quick glance at the field showed that it was
embarrassingly primitive. It was not an experimental science at all, where one
can test hypotheses with precise instruments, but rather a collection of loose,
highly speculative theories. Cosmologists engaged in heated debates about
whether the universe was born in a cosmic explosion or whether it has always
existed in a steady state. But with so little