How does the universe work? Understanding the Universe's birth and
its ultimate fate are essential first steps to unveil the mechanisms of
how it works. This, in turn, requires knowledge of its history, which
started with the Big Bang.
Previous NASA investigations with the Cosmic Microwave Background
Explorer (COBE) and the Wilkinson Microwave Anisotropy Probe (WMAP) have
measured the radiation from the Universe when it was only 300,000 years
old, confirming theoretical models of its early evolution. With its
improved sensitivity and resolution, ESA's Planck observatory probed the
long wavelength sky to new depths during its 2-year survey, providing
stringent new constraints on the physics of the first few moments of the
Universe. Moreover, the possible detection and investigation of the
so-called B-mode polarization pattern on the Cosmic Microwave Background
(CMB) impressed by gravitational waves during those initial instants
will provide clues for how the large-scale structures we observe today
came to be.
Observations with the Hubble Space Telescope and other
observatories showed that the Universe is expanding at an
ever-increasing rate, implying that some day - in the very distant
future - anyone looking at the night sky would see only our Galaxy and
its stars. The billions of other galaxies will have receded beyond
detection by these future observers. The origin of the force that is
pushing the Universe apart is a mystery, and astronomers refer to it
simply as "dark energy". This new, unknown component, which comprises
~68% of the matter-energy content of the Universe, will determine the
ultimate fate of all. Determining the nature of dark energy, its
possible history over cosmic time, is perhaps the most important quest
of astronomy for the next decade and lies at the intersection of
cosmology, astrophysics, and fundamental physics.
Knowing how the laws of physics behave at the extremes of space
and time, near a black hole or a neutron star, is also an important
piece of the puzzle we must obtain if we are to understand how the
universe works. Current observatories operating at X-ray and gamma-ray
energies, such as the Chandra X-ray Observatory, Fermi Gamma-ray Space
Telescope, XMM-Newton, are producing a wealth of information on the
conditions of matter near compact sources, in extreme gravity fields
unattainable on Earth.
(From : http://science.nasa.gov)
