According to a paper published in the latest issue of Physical Review X, an international team spent 16 years studying a pair of "extreme stars" known as "pulsars", and the results once again proved that Einstein's "general theory of relativity" about gravity was correct. It is reported that this study is the most rigorous test of Einstein's famous theory and has been supported by researchers in 10 countries.
Einstein's general theory of relativity predicts that huge objects distort space-time around them. NASA's gravity probe B found that space-time around Earth is indeed bent by earth and distorted by the rotational motion of the earth.
General relativity was reportedly developed by Einstein et al. since 1907 and was finally largely completed in 1915. In general relativity, gravity is described as a geometric property (curvature) of space-time. General relativity predicts the flow of time, the geometry of space, the motion of free fall, and the propagation of light, such as time expansion within gravitational fields, gravitational redshift of light, and gravitational time delay effects.
The predictions of general relativity have so far been verified by all observations and experiments. Although general relativity is not the only theory describing gravity today, it is the most concise theory that can be consistent with experimental data.
A pair of pulsars constitute a "near-perfect gravity laboratory," and 16 years of research is the most rigorous test of Einstein's famous theory.
An international team of researchers, led by Michael Kramer at the Max Planck Institute for Radio Astronomy in Germany, studied a pair of pulsars to test Einstein's force theory in the "most accurate laboratory" to date.
Discovered by team members in 2003, the pair orbit each other in just 147 minutes at a speed of about 1 million km/h, with one pulsar spinning 44 times per second. The pair are young and have a rotation cycle of 2.8 seconds. It is their movements with each other that can serve as a near-perfect gravity laboratory.
The team looked at the pair of pulsars and found that light was indeed delayed by the intense space-time curvature caused by gravity.
A pulsar is a highly magnetized spinning compact star that emits a beam of electromagnetic radiation from its magnetic poles. They weigh more than the sun, but they are only about 15 miles wide, so they are incredibly dense objects that produce radio beams that sweep across the sky like lighthouses.
Using seven radio telescopes in Australia, the United States, France, Germany, the Netherlands and the United Kingdom, the team observed the pair of pulsars and found that light was indeed delayed by the intense space-time curvature caused by gravity.
General relativity has long predicted this delay, but it was first observed. That said, a 16-year study of two extreme stars confirmed that their motion patterns were consistent with general relativity predictions.
Professor Ingrid Stairs of the University of British Columbia in Canada, who participated in the study, said the researchers tracked the propagation of radio photons emitted by pulsars and tracked their movements in the strong gravitational field of the associated pulsars, only to see for the first time that due to the strong curvature of space-time around the companion stars, the light was not only delayed, but also deflected by a small angle of 0.04 degrees.
"Never before has such an experiment been conducted at such a high curvature of space-time." He said.
It is reported that Einstein's theory of general relativity has a very important application in astrophysics.
For example, it predicts that after the end of some massive stars, a region of space-time will be so distorted that all matter (including light) will not be able to escape from the "black hole".
The theory also predicts that the deflection of light in the gravitational field will form a gravitational lensing phenomenon, which makes it possible to observe multiple images of the same celestial body in distant locations.
General relativity also predicts the existence of gravitational waves. Gravitational waves have been directly observed by the Laser Interferometer Gravitational Wave Observatory in September 2015.
In addition, general relativity is the theoretical basis for the "expanding cosmic model" in modern cosmology.
Text/Nandu reporter Chen Lin