Another Test is Passed by Einstein's Theory of General Relativity, having Implications for Dark Matter and Dark Energy

                               The Theory is accurate to at least one quadrillionth of a part

Space-Time Curvature

 

VITAL LESSONS

• A fundamental tenet of Einstein's current theory of gravity was put to a razor-sharp test by researchers. With a quadrillionth of a part accuracy, the theory held up.
• The equivalence principle, which states that inertial and gravitational mass are equivalent, was built into Einstein's theory of gravity.
• Some alternative theories of gravity are ruled out by the most recent test, but not all of them. The findings of the study have important repercussions for hypothetical concepts like dark energy and dark matter.

 

Researchers tested a fundamental tenet of Einstein's theory of general relativity, the contemporary theory of gravity, with extreme precision using a satellite orbiting the Earth. It is up for debate whether gravitational mass and inertial mass are the same things. With an accuracy of one part in a quadrillion, the researchers discovered that two things on board the satellite descended toward Earth at the same velocity. This practical application of Einstein's theory has important ramifications for ongoing cosmic puzzles, such as the existence of dark matter and dark energy.

 

The Ancients were Duped

The Universe is held together by gravity, which pulls on distant galaxies and leads them in an endless cosmic dance. Both the mass of the items and their distance from one another influence the strength of gravity. More mass results in a stronger feeling of gravity. "Gravitational mass" is the formal term for this kind of mass.

 

The second characteristic of mass is inertia. This is an object's propensity to resist motion changes. In other terms, heavier objects are more difficult to move: a bicycle is simpler to push than a car. "Inertial mass" is the formal term for this kind of mass.

 

There is no justification for presuming that inertial mass and gravitational mass are equivalent. One controls the gravitational force, while the other controls motion. Philosophers in ancient Greece noted that a hammer and a feather fall differently. If they were different, heavy and light items would fall at different rates. Undoubtedly, heavier objects appear to fall faster than lighter ones. Although it is now clear that air resistance is to blame, this wasn't always the case.

 

When Galileo conducted a series of experiments in the 17th century using ramps and spheres of various masses to demonstrate that objects of varying masses fall at the same rate, the situation was made clear. (His frequently famous experiment involving the falling of balls from the Tower of Pisa is likely fictitious.) And in 1971, Astronaut David Scott successfully recreated Galileo's experiment on the airless Moon in which he dropped a hammer and a feather, showing that they fell indistinguishably from one another. The Greeks of antiquity had been duped.

 

Dark Speculation

The equivalence principle, which states that inertial and gravitational mass are equivalent, was built into Einstein's theory of gravity. The majority of the time, general relativity accurately predicts how objects will fall, making it the most popular theory of gravity among scientists.

 

The majority of situations do not necessarily mean all of them, though, and astronomical measurements have uncovered several puzzling riddles. For starters, galaxies revolve more quickly than Einstein's general theory of relativity or the stars and gases that make up their interiors can explain. The existence of dark matter, or something that does not radiate light, is the most widely accepted explanation for this disparity. The discovery that the Universe is expanding faster is another cosmic mystery. Scientists have proposed that the Universe is filled with dark energy, a repellent type of gravity, to explain this anomaly.

 

These, however, are just questions of well-informed speculation. It's possible that our understanding of gravity and the principles of motion is incomplete. We must validate Einstein's theory of general relativity with extreme precision before we can be certain that dark matter and dark energy exist. To accomplish that, we must demonstrate the validity of the equivalence principle.

 

Modern attempts to test the equivalence principle are significantly more accurate than those made by Isaac Newton in the 1600s. Astronomers demonstrated in the 20th century that inertial and gravitational mass are identical to an accuracy of one part in 10 trillion by reflecting lasers off mirrors Apollo astronauts left behind on the moon. It was a remarkable accomplishment. The most recent trial, though, went even further.

 

Another Test for General Relativity is Passed

In 2016, the MicroSCOPE cooperation, a team of scientists, sent a satellite into orbit. The scientists were on board with titanium and platinum cylinders, and their goal was to test the equivalency principle. They shielded their device from vibrations and minute gravitational changes caused by neighbouring mountains, subterranean oil and mineral deposits, and other factors by placing it in space. Using electric fields, the researchers kept track of where the cylinders were located. According to the theory, if the two objects had different orbits, they would need to be held in place by two different electric fields.

As a result of their discovery that the necessary electric fields were identical, scientists were able to calculate that any variations between inertial and gravitational mass amounted to less than one part in a quadrillion. They essentially validated the equivalence principle precisely.

 

Although this is a predictable result from the perspective of general relativity, it has very significant ramifications for the investigation of dark matter and dark energy. While those theories are widely accepted, some researchers think that more recent theories of gravity can better account for the spinning characteristics of galaxies. Numerous of these opposing views suggest that the equivalence principle is not entirely accurate.

 

The equivalence principle was not broken during the MicroSCOPE measurement. Some alternative theories of gravity are disproved by its findings, but not all of them. A follow-up experiment called MicroSCOPE2, which is currently being prepared, should be around 100 times more accurate than its predecessor. If it detects violations of the equivalence principle, it will provide scientists with vital direction for creating fresh and more accurate theories of gravity.