Einstein’s Theory of Relativity Proved Right on another Galaxy

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The Theory of Relativity, as proposed by Albert Einstein over 100 years ago has been proven right in another Galaxy for the first time, validating General Relativity on a large astronomical scale.

Most of us consider Albert Einstein to be one of the greatest minds of the 20th century. By the time he visited the United Kingdom in the 1920s, he was world famous, often compared to Galileo and Newton.

However, most people, including many physicists, did not understand Einstein’s greatest achievement – The General Theory of Relativity. Comic genius Charlie Chaplin once said to Einstein, “They are cheering us both, you because nobody understands you, and me because everybody understands me.”

This isn’t surprising; like the life of most theoretical physicists, Einstein’s life had its ups and downs. In the first half of the 20th century, there were no advanced tools to validate Einstein’s theory of relativity. This changed in the latter half of the century when technological advancements helped scientists prove beyond reasonable doubt that Einstein was right about gravity.

 

Validation of General Relativity

Amid the chaos of the First World War, Einstein proposed his theory of general relativity, which explained how gravity works. Over the years, General Relativity has been subjected to a series of tests and has been proved correct, time and again. Although, all of these precision tests were carried out within our solar system. 

The latest research by Dr. Thomas Collett and his team of astronomers used the European Southern Observatory’s large telescope and NASA’s Hubble Space Telescope to test the theory of General Relativity in a nearby galaxy to validate it on a large astronomical scale.

 

The Expanding Universe

It is now widely accepted by scientists that the Universe is expanding. But, earlier, there was no unanimity on this. There were two camps – those who supported the Big Bang Theory and those that backed the Steady State Theory. It was Edwin Hubble who shifted the weights in favor of the Big Bang Theory, after analyzing the galactic redshifts. He found that galaxies are drifting apart as hypothesized by the big bang theory.

A major addition to the concept of the expanding universe was made in 1998. After measuring the speed at which the Universe expands, two teams of astronomers claimed that compared to past data, the Universe is currently expanding at a faster rate. For this 2011 Nobel Prize-winning discovery’s results to be true, the theories of gravity as explained by Einstein’s General Relativity must also be true on cosmological scales.

 

Gravitational Lensing

According to Einstein’s theory, objects of enormous size can deform space-time. To explain it differently; the light path, which is normally straight, bends or is deflected near a massive object like a star or galaxy. This gives rise to an occurrence called strong gravitational lensing. This happening was proved in 1919 by Sir Arthur Eddington who carried out the first test on Einstein’s concept of space-time distortion.

We know that normal lens bend light; a process known as refraction. Something similar happens in gravitational lensing. Here the gravitational field of massive stars and galaxies acts as the lens, bending light.

 

The Experiment proves General Relativity correct on a galactic scale

The current experiment used galaxies to validate General Relativity. So, if three things – our sight, the massive light-bending object (galaxy), and the background object (galaxy) – are alighted in a straight line, we can observe the phenomenon of gravitational lensing. The observer - our eye, telescope, camera, etc. – will notice multiple images of the background galaxy. Scientists can then use the separation between the background images and the mass of the massive galaxy (acting as a lens) to prove the theory of gravity as proposed by Einstein in General Relativity.

Even though scientists are well aware of hundreds of strong gravitational lenses, most of them could not be used, as they are situated too far away to accurately measure the mass. Hence, scientists used ESO325-G004 – a galaxy that’s just 500 million light-years from us – as the lens.

The team of astronomers measured the speed at which the stars moved in Galaxy E325 using the large telescope in Chile. With the data, they were able to deduce the amount of mass in the lens galaxy that’s required to hold the stars in its orbit. The findings were then compared to the separation of multiple images of the background galaxy as observed by the Hubble Space Telescope. With the help of the most advanced and precise tools available today, scientists were able to prove General Relativity as proposed by Einstein in 1915.

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Story Source:  Materials provided by University of Portsmouth. (Content may be edited for style) Photo Credit: Bryan Goff (The photograph provided bears no relation to the study.)