
During
the past two decades, scientists have made astonishing discoveries
and raised profound questions about the contents and evolution of the universe.
These new insights – derived from observation of exploding stars called supernovae,
from analysis of the cosmic
microwave background (CMB), from measurements of ghostly particles called neutrinos and
examination of ultra-high-energy collisions of atomic nuclei, from wide-angle
sky surveys, and from many other sources – are so revolutionary
that they cannot be explained by traditional ideas and methods.
To name only a few: About 95 percent of all the matter and
energy in the cosmos exists in one or more “dark” forms
radically different from the familiar protons, neutrons,
electrons and forces we know. The universe is expanding at
an accelerating rate, apparently driven by some exotic force
called dark
energy. The “empty” vacuum of
space is actually seething with activity that researchers
do not fully understand. And that same empty space is also
pervaded by super-high-energy particles such as gamma rays
and cosmic
rays, whose origins are still unclear.
Comprehending these and other mysteries requires far more
than astronomy. It demands an integrated approach in which
particle physics, cosmology, quantum theory, nuclear physics,
deep underground experiments and pioneering theoretical ideas
combine with space- and ground-based celestial observations
to create a synthesis.
NSF already supports many such efforts, including projects
to further analyze the cosmic microwave background; detect
and characterize the dark matter that holds galaxies together;
investigate dark energy through several kinds of observations;
and study those mysterious high-energy cosmic rays, which
have presumably been propelled to by some equally mysterious
sort of cosmic accelerator.
In addition, NSF funds the world’s largest and most
ambitious gravity-wave observatory, LIGO,
which is devoted to detecting and categorizing evidence for
one of the extraordinary predictions of Einstein’s
general theory of relativity: the ripples in space-time caused
by acceleration of enormous masses, such as black holes or
neutron stars.
In the future, NSF plans to collaborate with other federal
agencies to invest in the highly sensitive instruments and
technologies – and the improved experimental sophistication – that
will be needed to address the most pressing questions in
the physics of the universe. Among them are experiments to
test the prediction that protons ultimately decay, measure
the masses of the three “flavors” of neutrinos,
understand the origin of elements heavier than iron (which
are not created naturally in stellar
fusion), determine how cosmic accelerators work, and
describe the behavior of light and matter in extreme energy-density
conditions.
These are exhilarating times in cosmology and physics. With
NSF’s help, scientists are on the verge of revelations
that will be every bit as significant as those that produced
the Copernican revolution, the Newtonian era, and the age
of Einstein.
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