Gravity is one of the four fundamental forces
of nature.
Gravity is the force that structures the universe - it shapes space and
alters time - but gravity is still shrouded in mystery. The existence of
tiny gravitational ripples in the fabric of space is a direct prediction
of Einstein's theory of space, time and gravitation known as his General
Theory of Relativity. Gravitational waves pass directly through any object
they encounter and cause everything including space itself to alternately
stretch and shrink in different directions, but only by an infinitesimal
amount. They cause things to vibrate as do sound waves. Space should
be full of gravity wave 'sounds': intense drum beats from the collision
of black holes; chirrups like bird calls when neutron stars and black holes
spiral together; pure tones from rapidly rotating neutron stars and continuous
murmurs from the big bang itself. Vast amounts of gravitational energy are
thought to be out there and passing through us all the time.
Scientists aim to detect the new gravitational
spectrum to enable humanity to directly 'listen' to black holes and the
birth of the universe itself.
The first generation of detectors were based on giant bars of metal designed
to vibrate in response to gravitational waves. Five of these were built
around the world - one of them at the University of Western Australia. Today,
large teams of physicists, engineers, mathematicians, computer programmers
and technicians are testing and developing a new generation of detectors
based on devices called Laser Interferometers. These devices
use high power lasers, supermirrors, advanced vibration isolators and state-of-the-art
digital techniques. Today we are at a point where the upcoming detectors
are certain to detect known powerful signals produced when superdense neutron
stars spiral together and merge to create a black hole.

