Friday, November 17, 2000, 16:00
WHGA Auditorium
Prof. K. Danzmann, Hannover
Abstract:
Gravitational waves have been predicted more than 80 years ago by
Einstein as a consequence of his Theory of
General Relativity. Although gravitational waves have not yet been seen
directly, their indirect influence can be observed in the binary pulsar PSR 1913+16. This
binary's two neutron stars are spiralling together
at just the rate predicted by gravitational
radiation reaction.
Gravitational waves, once observed, promise us a radically new view of
the universe. Electromagnetic waves are incoherent superpositions of
emission from individual electrons, atoms or molecules in low-density
regions. But gravitational waves will tell us about the coherent motion
of huge amounts of mass-energy and the vibrating, non-linear spacetime
curvature itself.
Several kilometersize laser interferometric gravitational wave detectors
are now under construction in the US and Europe (LIGO, VIRGO, GEO).
It is expected that in the first few years of the next millenium a world-wide
network of ground-based detectors will begin routine observations of
gravitational waves in the high-frequency band between 1 Hz and 10 kHz,
aiming at sources such as coalescing binaries or supernovae.
The low-frequency
band from 1 Hz down to less than a milli-Hertz is populated by waves emitted
by sources as diverse as supermassive black holes at large red-shifts
to short period binaries in our own galaxy . This band will never be
observable on the ground due to the unshieldable background of Newtonian
gravity gradients on earth. This is the domain of detectors in space.
The European Space Agency ESA has just recently selected a spaceborne
laser interferometric gravitational wave detector (LISA) as one of the
cornerstone missions in its future Horizon 2000 Plus program.
This talk will give an overview of
current efforts and future plans for gravitational wave detection on the ground
as well as in space.