Einstein developed a theory of gravity that is as stupefying as it is accurate. Yet Einstein’s theory of gravity is pushed to new limits as scientists study the complex-dynamics of a triple-star solar system. Astronomers have discovered a unique, triple-star system that can shed light onto the medium that bends light itself—gravity. Einstein taught that gravity is an effect that is felt when matter warps the fabric of space-time. It is what ties the solar system together into a single cosmic dance. Yet physicists have a poor understanding of Einstein’s theory of gravity when the smallest ontological depths of nature are probed.
The triple-star system consists of two white dwarfs and a super dense neutron star or ‘pulsar’. A white-dwarf is a star that has reached the end of its life cycle with a mass equivalent to the sun packed into the volume the size of Earth. A pulsar star is about the size of a white-dwarf but slightly heavier and spins rapidly. The constituency of this cosmic heavy-weight champion is mostly neutrinos—particles with no net charge but are slightly heavier than protons. Hence the term neutron in neutron star. The pulsar is roughly 4,200 light-years a way, tangoing with a fiery brethren in an orbit smaller than the Earth’s around the sun, tangoing with yet another fiery brethren even further a way.
The pulsar spins at 366 spins per second and pulsates beams of electromagnetic radiation. Pulsars have long been utilized by astronomers as a cosmic calibrator when detecting evasive gravitational waves. The astronomers made some of the most precise measurements in the history of astrophysics, reports Anne Archibald of the Netherlands Institute for Radio Astronomy. The relative position of stars measured by the astronomers was accurate to hundreds of meters, which by cosmic standards is a precision equivalent to pinpointing a needle in a haystack.
Einstein’s General Theory of Relativity is the most accurate description of gravity physicists have yet contrived (discovered?). Nevertheless, Einstein’s General Theory of Relativity is incompatible with its sister theory of the very small—quantum theory. Physicists believe Einstein’s General Theory of Relativity breaks down under extreme conditions. The triple-star system is an extraordinary disturbance within the very fabric of space-time where the laws of physics were meant to be broken. Einstein’s Theory of Gravity is pushed to new limits within this cosmic vortex and gives physicists the kick in the pants they need to meld a more complete theory of gravitation that is compatible with quantum theory.
So what limits of Einstein’s General Theory of Relativity might scientists discover? Astronomers believe the triple-star system is the best hope to discover a violation of the Equivalence Principle. The Equivalence principle states that the gravitational motion of a body is determined by its position and velocity in space-time rather than by its internal structure. When a star collapses into a neutron star, some of the stars mass is converted into gravitational energy that binds the star together. The Equivalence Principle predicts the gravitational energy that binds the neutron star will behave as if it were a mass. Alternatives to the General Theory of Relativity predict otherwise.
The triple-star system is an excellent means to discover whether the Equivalence Principle breaks down. In particular, the Equivalence Principle predicts that the gravitational effect of each star within the three-star system will hold equal. If the white-dwarf on the outskirts of the three-star system has a slightly different gravitational effect on the other two stars, then the Equivalence Principle is broken. Thus, within the quirky dynamics of this complex solar system, Einstein’s Theory of Gravity is pushed to new limits in a cosmic terrain where there are none.
By Nathan Cranford