[ad_1]
We are celebrating today, May 29, 2019, the first hundred years of a legendary eclipse and special scientific expedition designed to observe it carefully. It was the first deliberate attempt to test Albert Einstein's new theory of gravity (or general relativity) – and his results made Einstein a celebrity of superstar greatness.
A hundred years ago, excitement around the expedition was palpable. Four years of war had made Britain and Germany enemies, but in early 1919 – in an act of international reconciliation and bold scientific planning – the British expedition embarked on for the tropics in order to capture the best glimpse of the total eclipse of May 29 the sun.
Their goal was to determine which theory of gravity was the right one: that of Einstein, born in Germany, or that of the British icon Isaac Newton.
What was the connection between eclipse and gravity?
Einstein had predicted that the light from the stars passing through the sun as she was heading toward Earth would be slightly deflected by the gravity of the sun.
To test this, he suggested taking pictures during a total solar eclipse, when the stars surrounding the sun became visible for a few minutes. He hoped that these photos would indicate a shift in the position of the stars relative to the images of the same stars when they are no longer near the sun.
According to the standard optical and gravitational theory of the time, however, the light should move in straight lines. He has no mass, so, according to Newton's theory, he could not be deflected by gravity as a tennis ball hit the arches of the net to the ground.
But Einstein did not tie the force of gravity directly to the masses of two bodies as Newton did; Instead, he predicted that the large gravitational field of the sun was bending the space-time around him. And that meant that the rays of light had to follow curved paths when they passed in front of the sun.
This curvature is extremely small: on their photographic plate representing the stars, the British astronomers had to be able to discern changes of position of about a fiftieth of a millimeter!
The technical skills needed for such a delicate task were enormous and deserve to be celebrated today. The results conclusively showed that the sun was deviating stars, and a new scientific star was born.
In the next edition of Cosmos quarterly magazine, published on June 6, Robyn Arianrhod delivers a fascinating and detailed history of the eclipse that cemented Einstein's reputation. Order your copy here.
[ad_2]
Source link