Albert Einstein's Theory of General Relativity has passed its most stringent test yet after scientists observed their experiment on the weak-equivalence principle.
Scientists announced that Einstein's theory of general relativity has proven itself to be a fundamental truth of our universe. The team conducted what it calls the "most precise test" of one of the theory's key aspects using a mission dubbed Microscope.
Weak Equivalence Principle
A scientist at French aerospace lab ONERA, Manuel Rodrigues, the author of a new study published in the journal Physical Review Letters, said, "I have been working on this subject for more than 20 years, and I realize the luck I had to be the project manager of the science instrument and the co-investigator of this mission."
The project sent a satellite into Earth's orbit that contained two objects: a platinum alloy and titanium alloy. Rodrigues said that the selection of the objects was based on technology considerations, including whether or not the materials were easy and feasible to make inside a laboratory, as per CNET.
The alloys were blasted into Earth's orbit because stuff up there exists in our planet's gravitational field without any other forces acting on them. Once the satellite was in space, the researchers then began their tests, which lasted for years, on whether the platinum bit and titanium bit fell in the same way as they orbited Earth.
The researchers found their answer to that question, and they did, to an extremely precise degree. Rodrigues argued that the most thrilling part of the project was to develop an instrument and a mission that nobody else has done before at such a level of accuracy.
According to Science Alert, the weak equivalence principle is relatively simple to observe in action. It states that all objects accelerate identically in the same gravitational field when no other influences act upon them, regardless of their mass or composition.
Theory of General Relativity
It was most famously demonstrated to dramatic effect in 1971 when astronaut Dave Scott dropped a hammer and a feather simultaneously from the same height while standing on the Moon. With air resistance to slow down the feather, the two objects, of widely different weights and composition, dropped to the lunar surface at the same speed.
During the project, the team ran multiple experiments using masses suspended in free-fall, providing a total of five months worth of data. Roughly two-thirds of that data involved pairs of test masses of different masses of different compositions, alloys of titanium and platinum. While the remaining one-third involved a reference pair of masses of the same platinum composition.
The Microscope team's results, which are the culmination of 20 years of research, revealed that acceleration in pairs of objects in free fall differed by no more than 1 part in 10^15. This means that they found no violations in the weak equivalence principle larger than that.
On top of placing constraints on deviations in the weak equivalence principle, the team's findings also disfavor any deviations in Einstein's 1915 theory of gravity, general relativity, as a whole, Space reported.
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