Astrophysical fluid dynamics she pulls in her arms. These stars gradually slow down over the eons, but those bodies that are still spinning rapidly may emit radiation that from Earth appears to blink on and off as the star spins, like the beam of light from a turning lighthouse. This "pulsing" appearance gives some neutron stars the name pulsars. After spinning for several million years pulsars are drained of their energy and become normal neutron stars. Few of the known existing neutron stars are pulsars. Only about 1,000 pulsars are known to exist, though there may be hundreds of millions of old neutron
Tractor beam Intended applications include remotely manipulating space objects at distances up to about 100 km, removal of space debris, and retrieval of adrift astronauts or tools on-orbit. In March 2011, Chinese scientists posited that a specific type of Bessel beam (a special kind of laser that does not diffract at the centre) is capable of creating a pull-like effect on a given microscopic particle, forcing it towards the beam source. The underlining physics is the maximization of forward scattering via interference of the radiation multipoles. They show explicitly that the necessary condition to realize a negative (pulling) optical force is the