A strange stellar pair nearly 7,000 light-years from Earth
has provided physicists with a unique cosmic laboratory for studying the nature
of gravity. The extremely strong gravity of a massive neutron star in orbit
with a companion white dwarf star puts competing theories of gravity to a test
more stringent than any available before.
Once again, Albert Einstein's General Theory of Relativity,
published in 1915, comes out on top.
At some point, however, scientists expect Einstein's model
to be invalid under extreme conditions. General Relativity, for example, is
incompatible with quantum theory. Physicists hope to find an alternate
description of gravity that would eliminate that incompatibility.