Abstract
Gravitational radiation antennas have been operating since 1965. A large number of pulses have been observed, coincident on widely separated antennas. These data and the Supernova 1987A observations are reviewed. It is concluded that some of these pulses may have a gravitational radiation origin.
Introduction
The theory of elastic solid, and interferometer gravitational radiation antennas has been under development at the University of Maryland since 1957. Aluminum bar systems have been operating continuously since 1965.
It is very important to stress that the output of a gravitational antenna (and a neutrino detector as well) differs in fundamental ways from the output of an optical telescope.
When an optical telescope collects light from a star, it can be concluded that most of the light came from the star.
A gravitational antenna - bar or interferometer - has electrical output pulses. For a single antenna, there is no way to guarantee that observed pulses are not noise of internal origin or noise from local disturbances such as lightning. If statistically significant numbers of coincident pulses are observed on widely separated antennas, this is evidence that the pulses have a common origin. Directive information is useful but not conclusive, in identifying the source.
There is no way to be certain that such pulses are or are not due to gravitational radiation.
Therefore the statement which is frequently made that gravitational radiation has not yet been observed is meaningless.