The galaxy
cluster Abell 1689 is famous for the way it bends light in a phenomenon called
gravitational lensing. A new study of the cluster is revealing secrets about
how dark energy shapes the universe. Full story.
A mysterious
quantity known as dark energy makes up nearly three-fourths of the universe,
yet scientists are unsure not only what it is but how it operates. How, then,
can they know this strange source exists?The expanding universe
In 1929,
American astronomer Edwin Hubble studied exploding stars known as
supernovae to determine that the universe is expanding. Since then, scientists
have sought to determine just how fast. It seemed obvious that gravity, the
force which draws everything together, would put the brakes on the spreading
cosmos, so the question many asked was, just how much was the expansion
slowing?........In the 1990s,
two independent teams of astrophysicists again turned their eyes to distant supernovae
to calculate the deceleration. To their surprise, they found that the expansion
of the universe wasn't slowing down, it was speeding up! Something must be
counteracting gravity, something which the scientists dubbed "dark energy."......To Read More....
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