(ORDO NEWS) — General relativity has withstood perhaps the most difficult challenge to date.
The theory, which Albert Einstein published in 1916, revolutionized our understanding of physics and space. She explains gravity as a consequence of the flexibility of space-time: massive objects deform space-time, creating cavities around which other bodies revolve.
Scientists have repeatedly tested general relativity over the past 105 years, trying to find situations or circumstances in which it turns out to be insufficient. They haven’t found one yet.
In the new study, scientists report the results of one of the most ambitious and complex challenges to general relativity ever undertaken. They analyzed observations of the binary pulsar system made by seven different radio telescopes around the world from 2003 to 2019.
Pulsars are a type of neutron star or superdense stellar remnant that emit powerful beams of radiation and particles from their magnetic poles. These beams are continuous, but they appear to be pulsating (hence the name) because pulsars rotate; this light can only be seen when the pole is pointed at the Earth.
The pair of pulsars the group studied are about 2,400 light years from Earth. One of the pulsars rotates 44 times per second, while the other completes one revolution every 2.8 seconds. According to team members, the two objects revolve around a common center of mass every 147 minutes, each moving through space at a speed of about 1 million kilometers per hour.
“This rapid orbital motion of compact objects like these – they are about 30% more massive than the Sun, but only about 24 kilometers across – allows us to test many different predictions of general relativity – just seven!” Manchester of the Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia’s national science agency.
And quality matched quantity: the study achieved levels of accuracy unprecedented for testing general relativity, team members said.
“In addition to gravitational waves and light propagation, our accuracy also allows us to measure the ‘time dilation’ effect that causes clocks to slow down in gravitational fields,” said Manchester. “We even need to take into account Einstein’s famous equation E = mc 2 when considering the effect of electromagnetic radiation emitted by a rapidly rotating pulsar on orbital motion.”
The study showed that all seven tested predictions were confirmed. Thus, general relativity remains undefeated – but that doesn’t mean researchers should stop trying to find cracks in it.
“General relativity is incompatible with other fundamental forces described by quantum mechanics. Therefore, it is important to continue to conduct the most rigorous tests on general relativity as much as possible in order to figure out how and when the theory collapses,” said co-author Robert Ferdman, a physicist at the University of Eastern England, in the same statement.
“Finding any deviation from general relativity would be a major discovery that would open a window to new physics beyond our current theoretical understanding of the universe,” Ferdman added. “And that may help us ultimately discover a unified theory of the fundamental forces of nature.”
The new study was published on December 13 in Physical Review X.
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