Solar eclipse in Brazil helped prove Einstein’s theory – 04/05/2024 – Science

NASA should take advantage of the total solar eclipse, next Monday (8), to conduct scientific studies that would not be possible if it weren’t for the Moon blocking sunlight. One of the most important experiments in history, carried out in Sobral, Ceará, and on the island of Príncipe, in Africa, was also thanks to a phenomenon of this type.

The experiment, carried out in 1919, made it possible to confirm that gravity can bend the trajectory of light to the extent predicted in Albert Einstein’s theory of general relativity.

But not only that. The experiment —partly on Brazilian land— showed that the German physicist was right in relation to the predicted deviation of light.

“The results of the expeditions to Sobral and Príncipe can leave little doubt that the deflection of light occurs in the vicinity of the Sun and that it is by the amount demanded by Einstein’s theory of generalized relativity, attributed to the Sun’s gravitational field,” said Royal Society, in London, on November 6, 1919, the team led by Arthur Eddington and Frank Dyson.

If it may now seem like something that has already become common knowledge, at the time it was uncertain what would be found in the experiment and there was distrust among physicists about Einstein’s conclusions.

What does the eclipse have to do with Einstein?

The question begins with the discovery that light always has the same speed in a vacuum: 300 thousand km/s. According to Einstein, the only explanation for this is if your speed influences the way you perceive the world, shortening space and lengthening time in relation to observers. There was, in 1905, the theory of special relativity.

Einstein then realized that accelerating is the same as being under the influence of a gravitational field. If variations in speed alter the geometry of space-time, objects that generate gravity must also cause changes.

Basically, the laws of geometry bend. In flat space, the angles of a triangle add up to 180 degrees, but in curved space they can add up to more or less, depending on the light that scans this geometry. When light curves, it is actually traveling in a straight line, but in a curved space.

Einstein realized this and was able to describe the reasoning with the work of mathematician Georg Riemann.

The Sun, with its enormous gravity, would therefore be a good point to observe whether the light that passes close to it, derived from distant stars, suffers a small deviation, which would cause the star to appear out of its normal position in the sky.

The problem is the brightness of the Sun, which prevents us from seeing the background of nearby stars — unless something was in front of it, that is, in an eclipse with the Moon covering it.

According to Einstein’s calculations, the light from background stars in the vicinity of the solar disk would be deflected by 1.75 arc seconds, equivalent to about 0.00048 degrees.

All that was needed was a suitable eclipse to confirm the calculations. And he came in 1919 — with a second in 1922, which reinforced the conclusions.

In 1925, in South America, more specifically in Rio de Janeiro, Einstein stated: “The problem that my mind formulated was answered by the luminous sky of Brazil.”