Cosmic Dance Offers Fresh Test for General Relativity

The death dance of a white dwarf star and a pulsar reveal relativistic frame dragging — also known as the Lense-Thirring effect — in which a fast-spinning object distorts the fabric of space-time around it. Such a mind-boggling effect is due to the brain-bending qualities of the two stars. The white dwarf orbits at speeds of up to a million kilometres per hour, making its year only about five hours long. The pulsar itself spins around more than two times per second. The white dwarf is the size of Earth and the pulsar is the size of a city — but both contain more mass than the Sun. The pulsar’s metronome-like radio emissions showed researchers how this extreme relativistic system pulls space-time around it, causing the pulsar’s orbit to wobble exactly as predicted by general relativity.