EPILOGUE 289
generation of satellites will be launched that will analyze gravitational
radiation in outer space from the instant of creation. The three satellites that make up LISA (Laser Interferometer Space Antenna), a joint
project of NASA and the European Space Agency, will be sent into orbit around the sun. These satellites will be capable of detecting gravitational waves emitted less than a trillionth of a second after the big
bang. If a gravity wave from the big bang still circulating around the
universe hits one of the satellites, it will disturb the laser beams, and
this disturbance can then be measured in a precise way, giving us
"baby pictures" of the instant of creation itself.
LISA consists of three satellites circling the sun arranged in a triangle, each connected by laser beams 3 million miles long, making it
the largest instrument of science ever created. This system of three
satellites will orbit the sun about 30 million miles from the Earth.
Each satellite will emit a laser beam with only half a watt of power.
By comparing the laser beams coming from the other two satellites,
each satellite will be able to construct an interference pattern of light.
If a gravity wave disturbs the laser beams, it will change the interference pattern, and the satellite will be able to detect this disturbance.
(The gravity wave does not make the satellites vibrate. It actually creates a distortion in the space between the three satellites.)
Although the laser beams are very weak, their accuracy will be astounding. They will be able to detect vibrations to within one part in a
billion trillion, corresponding to a shift Vioo the size of an atom. Each
laser beam will be able to detect a gravity wave from a distance of 9 billion light-years, which covers most of the visible universe.
LISA has the sensitivity to potentially differentiate between several
"pre-big bang" scenarios. One of the hottest topics in theoretical
physics today is calculating the characteristics of the pre-big bang universe. At present, inflation can describe quite well how the universe
evolved once the big bang took place. But inflation cannot explain why
the big bang took place in the first place. The goal is to use these speculative models of the pre-big bang era to calculate the gravity radiation emitted by the big bang. Each of the various pre-big bang theories
makes different predictions. The big bang radiation predicted by the
generation of satellites will be launched that will analyze gravitational
radiation in outer space from the instant of creation. The three satellites that make up LISA (Laser Interferometer Space Antenna), a joint
project of NASA and the European Space Agency, will be sent into orbit around the sun. These satellites will be capable of detecting gravitational waves emitted less than a trillionth of a second after the big
bang. If a gravity wave from the big bang still circulating around the
universe hits one of the satellites, it will disturb the laser beams, and
this disturbance can then be measured in a precise way, giving us
"baby pictures" of the instant of creation itself.
LISA consists of three satellites circling the sun arranged in a triangle, each connected by laser beams 3 million miles long, making it
the largest instrument of science ever created. This system of three
satellites will orbit the sun about 30 million miles from the Earth.
Each satellite will emit a laser beam with only half a watt of power.
By comparing the laser beams coming from the other two satellites,
each satellite will be able to construct an interference pattern of light.
If a gravity wave disturbs the laser beams, it will change the interference pattern, and the satellite will be able to detect this disturbance.
(The gravity wave does not make the satellites vibrate. It actually creates a distortion in the space between the three satellites.)
Although the laser beams are very weak, their accuracy will be astounding. They will be able to detect vibrations to within one part in a
billion trillion, corresponding to a shift Vioo the size of an atom. Each
laser beam will be able to detect a gravity wave from a distance of 9 billion light-years, which covers most of the visible universe.
LISA has the sensitivity to potentially differentiate between several
"pre-big bang" scenarios. One of the hottest topics in theoretical
physics today is calculating the characteristics of the pre-big bang universe. At present, inflation can describe quite well how the universe
evolved once the big bang took place. But inflation cannot explain why
the big bang took place in the first place. The goal is to use these speculative models of the pre-big bang era to calculate the gravity radiation emitted by the big bang. Each of the various pre-big bang theories
makes different predictions. The big bang radiation predicted by the