100 years ago, a total solar eclipse experiment confirmed Einstein’s theory of relativity

Negative photo of the 1919 solar eclipse taken from Príncipe Island. The position of the stars that were examined in the historic test of Einstein’s theory of gravity are shown in this picture.

A hundred years ago, in the aftermath of the first world War, a British astronomer looked at a solar eclipse for signs that a German physicist might be right about distortions in the universe.

The bold new theoretical ideas belonged to Albert Einstein, whose last name is synonymous with genius. But his name is not always that feeling of People thought that his theories described reality, and it took a special experiment during a solar eclipse to cement Einstein as a physics legend.

Solar eclipses are just as wonderful as they might feel: every couple of years, the moon is able to completely and correctly stain from the body of the sun as seen from our planet. As photos, taken by NASA’s Curiosity rover in March, 2019 disclaim, planets like Mars are not the same luck, even with two moons to work with. The position and size of the Earth, the moon happens to coincide exactly with the position and the size of the moon.

Related: In Photos: Testing the General theory of Relativity with the 1919 solar Eclipse

In addition to a spectacle, total solar eclipses provide opportunities to all types of research, such as the study of the corona — the sun’s outer atmosphere — or the nature of the reactions of the dimming of light. In 1919, Arthur Eddington and his research team to look for signs that the gravity of massive objects can bend light, proving Einstein right and a positive development of the theoretical physics outside of classical mechanics of Isaac Newton.

As starlight travels past could be distracted by the sun, by the huge bulk, the stars would appear in slightly different positions when seen from the Earth, after the passing of the sun. But when the sun is in the sky, it is still too light to see the nearby stars — except during a solar eclipse.

On May 29, 1919, Eddington observed a long solar eclipse from Principe, an island off the coast of West Africa. At the same time, astronomers names of the notes of the Brazilian city of Sobral. The team used portable instruments to take where the stars of the hyades cluster — the shape of the bull’s face in the constellation of Taurus — appeared to be in the air, and the comparison of these observations with Eddington’s earlier comments about where the stars normally seen in the night sky.

At their most pronounced, the findings show a maximum shift in starlight “is equivalent to the angle subtended by a quarter viewed from two miles away,” author Ron Cowen writes in his new book, “Gravity’s Century” (Harvard University Press, 2019).

Eddington got creative with his instrumentation for the particular experiment. “The expedition used coelostats, mirrors that are specially designed for observing the sun, which is responsible for reflecting light into the telescope lens,” said Cowen in an e-mail. “The mirrors were required because the telescopes, to simplify travel, had no mechanical apparatus to drive or rotate the steel tubes with the lenses. Normally, there would be such a mechanical device to the telescopes in the line of a target as the Earth rotated. If a telescope can not rotate, the stars move during a photographic exposure, and there appear vertical stripes instead of a sharp image.”

Instead of moving the entire telescope to keep the instrument fixed to the Hyades and the eclipse of the sun, a small clockwork device to move the mirrors to correct for the rotation of the Earth, Cowen added.

Related: solar Eclipse Paintings in the New Princeton Exhibition (Photos)

When the results came in, the scientists have calculated that the Hyades’ starlight had indeed shifted when passing by the sun on a path in the direction of the Earth.

Einstein conceived this possibility — that the gravity of an object with enough mass can bend light — when combining mathematical equations and thought experiments (which are performed in the imagination) to determine that the light will appear to travel at the same speed the set of observers who are traveling at a consistent speed. That is the Special theory of Relativity.

But when he began to think how light would appear when an observer is accelerating, he realized that space and time are interwoven into a single continuum, and that the gravity is a part of this substance; the gravity is just like the dive on a trampoline surface (space-time) where a ball (solid object) roll over. If the ball moves in a straight line, the dip changes its path.

Eddington’s pacifism drew criticism when he refused to fight in the first world War, and some have argued that the scientist held a bias when he supported Einstein, a German scientist, which he saw as an opponent past nationalist conflicts and the embrace of humanism. Cowen argues that Eddington’s religious beliefs — he was a Quaker complemented his support for Einstein’s ” bold, scientific progress. On the other hand, the writer and the physicist Daniel Kennefick argues that Eddington’s view on the world came secondary to the science that he thought was valid.

“It was no longer clear how to interpret the variables in Newton’s law of gravity in the light of the discoveries of the special theory of relativity,” said Kennefick in an e-mail. He added that the mass of the sun is important for the light deflection test, and according to Newton, the science of the sun speed through the universe, it was necessary to determine the mass. But Einstein’s 1915 Theory of General Relativity offered a simpler: “the sun’s movement through the universe it doesn’t matter because we move with the sun in that movement,” Kennefick said. This should experiment, like the light bending of the observations Eddington eventually did take hold merit.

Cowen’s book “the Gravity of the Century: Einstein’s Eclipse to take Images of Black Holes” was published May 6. Kennefick’s book “No Shadow of a Doubt: The 1919 Eclipse That Confirmed Einstein’s theory of Relativity,” was also published this year.

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