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: http://www.naic.edu/~pfreire/space/index04.html
Дата изменения: Sun Jan 27 18:53:09 2008
Дата индексирования: Tue Oct 2 05:29:07 2012
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Поисковые слова: aurora
Cosmology / Relativity / Gravity Wave Astronomy
One very important space
mission has already provided definite answers about cosmology, the
quest to understand the origin and fate of the Universe. This is NASA's Wilkinson Microwave
Anisotropy Probe, which announced its first results in 2003.
We
now know that the Universe is 13.7 +/- 0.2 billion years old, and that
the cosmic background radiation was emitted when it was only 380 000
years old. More intriguingly, we also know that more than 70% of the
mass of the Universe is "Dark Energy", and that this entity now
dominates universal expansion, and that its dominance wil grow stronger
and stronger with time. In a few years, we will witness the launch of
the Planck
Surveyor mission (ESA),
which will produce the definitive map of the cosmic microwave
background, enabling cosmologists to measure the fundamental constants
of the Universe with unprecedented precision. In 2011, the SuperNova
Acceleration Probe (SNAP) will start
measuring the properties of Dark Energy itself, which will allow us to
have a fairly good picture of the future of the Universe.
Astronomy has, so far, been
the exclusive study of electromagnetic waves and occasionally
neutrinos. Ground-based gravitational wave telescopes like LIGO and VIRGO now being completed; and
space-based telescopes like LISA
should open an entire new window on the Universe, by looking at the
gravitational radiation being emitted by extremely large or compact
sources, like double black holes, or coalescing neutron stars. By
studying neutron stars orbiting black holes, LISA will test some basic
predictions of general relativity (GR) to an extreme precision. Several
other missions are also going to test GR and its fundamental
assumptions: Gravity Probe B,
launched in April 2004, and STEP, still being
planned, are among the most important. The Space Interferometry Mission will
test GR by measuring stellar deflection to a precision of a
microarcsecond (a capacity that can also be used to search for extra-solar planets), and BepiColombo
will also help testing GR because with its precise measurement of the
gravitational field and motion of the planet Mercury (which was
the first GR test).