LONDON: The fact that scientists can see gravity perform the same in our solar system as it does in a distant star system helps confirm that the gravitational constant truly is universal.
Gravity, one of the four fundamental forces of nature, appears reassuringly constant across the universe, according to a decades-long study of a distant pulsar. This research helps to answer a long-standing question in cosmology: Is the force of gravity the same everywhere and at all times? The answer, so far, appears to be yes.
Astronomers using the National Science Foundation’s Green Bank Telescope in West Virginia and its Arecibo Observatory in Puerto Rico conducted a 21-year study to precisely measure the steady “tick-tick-tick” of a pulsar known as PSR J1713+0747. This painstaking research produced the best constraint ever of the gravitational constant measured outside our solar system.
Pulsars are the rapidly spinning, superdense remains of massive stars that detonated as supernovae. They are detected from Earth by the beams of radio waves that emanate from their magnetic poles and sweep across space as the pulsar rotates. Since they are phenomenally dense and massive, yet comparatively small — a mere 12–15 miles (20–25 kilometers) across — some pulsars are able to maintain their rate of spin with a consistency that rivals the best atomic clocks on Earth. This makes pulsars exceptional cosmic laboratories to study the fundamental nature of space, time, and gravity.
