Parallel Worlds Read Free Page B

universe, by far the largest amount, is
made of a totally unknown form of energy called dark energy, or the invisible
energy hidden in the vacuum of space. Introduced by Einstein himself in i9i7
and then later discarded (he called it his "greatest blunder"), dark
energy, or the energy of nothing or empty space, is now re-emerging as the
driving force in the entire universe. This dark energy is now believed to create
a new antigravity field which is driving the galaxies apart. The ultimate fate
of the universe itself will be determined by dark energy.
    No one at the
present time has any understanding of where this "energy of nothing"
comes from. "Frankly, we just don't understand it. We know what its
effects are [but] we're completely clueless . . . everybody's clueless about
it," admits Craig Hogan, an astronomer at the University of Washington at
Seattle.
    If we take the
latest theory of subatomic particles and try to compute the value of this dark
energy, we find a number that is off by 10 120 (that's the number 1
followed by 120 zeros). This discrepancy between theory and experiment is far
and away the largest gap ever found in the history of science. It is one of our
greatest embarrassments—our best theory cannot calculate the value of the
largest source of energy in the entire universe. Surely, there is a shelf full
of Nobel Prizes waiting for the enterprising individuals who can unravel the
mystery of dark matter and dark energy.
     
    INFLATION
    Astronomers are
still trying to wade through this avalanche of data from the WMAP. As it sweeps
away older conceptions of the universe, a new cosmological picture is
emerging. "We have laid the cornerstone of a unified coherent theory of
the cosmos," declares Charles L. Bennett, who led an international team
that helped to build and analyze the WMAP satellite. So far, the leading theory
is the "inflationary universe theory," a major refinement of the big
bang theory, first proposed by physicist Alan Guth of MIT. In the inflationary
scenario, in the first trillionth of a trillionth of a second, a mysterious
antigravity force caused the universe to expand much faster than originally
thought. The inflationary period was unimaginably explosive, with the universe
expanding much faster than the speed of light. (This does not violate
Einstein's dictum that nothing can travel faster than light, because it is
empty space that is expanding. For material objects, the light barrier cannot
be broken.) Within a fraction of a second, the universe expanded by an unimaginable
factor of 10 50 .
    To visualize the
power of this inflationary period, imagine a balloon that is being rapidly
inflated, with the galaxies painted on the surface. The universe that we see
populated by the stars and galaxies all lies on the surface of this balloon,
rather than in the interior. Now draw a microscopic circle on the balloon. This
tiny circle represents the visible universe, everything we can see with our
telescopes. (By comparison, if the entire visible universe were as small as a
subatomic particle, then the actual universe would be much larger than the visible
universe that we see around us.) In other words, the inflationary expansion was
so intense that there are whole regions of the universe beyond our visible
universe that will forever be beyond our reach.
    The inflation
was so enormous, in fact, that the balloon seems flat in our vicinity, a fact
that has been experimentally verified by the WMAP satellite. In the same way
that the earth appears flat to us because we are so small compared to the
radius of Earth, the universe appears flat only because it is curved on a much
larger scale.
    By assuming that
the early universe underwent this process of inflation, one can almost
effortlessly explain many of the puzzles concerning the universe, such as why
it appears to be flat and uniform. Commenting on the inflation theory,
physicist Joel Primack has said, "No theory as beautiful as this has ever
been wrong