Introduction to general relativity this energy loss would be too small to be detectable, but this energy loss was observed in 1974 in a binary pulsar called PSR1913+16. In such a system, one of the orbiting stars is a pulsar. This has two consequences: a pulsar is an extremely dense object known as a neutron star, for which gravitational wave emission is much stronger than for ordinary stars. Also, a pulsar emits a narrow beam of electromagnetic radiation from its magnetic poles. As the pulsar rotates, its beam sweeps over the Earth, where it is seen as a regular series of radio pulses, just
Beam riding to be powerful, as it is not necessary to use it for tracking as well. The main use of this kind of system is to destroy airplanes or tanks. First, an aiming station (possibly mounted in a vehicle) in the launching area directs a narrow radar or laser beam at the enemy aircraft or tank. Then, the missile is launched and at some point after launch is “gathered” by the radar or laser beam when it flies into it. From this stage onwards, the missile attempts to keep itself inside the beam, while the aiming station keeps the beam pointing