General relativity is Einstein’s famous theory about how gravity curves or bends light (with lots of other implications for physics and astrophysics!). He had presented ideas about special relativity (E = MC2) in 1905 , but wanted to extend that to include how gravity affected celestial bodies. In November 1915, he presented his general relativity to the Prussian Academy of Science.
The problem, of course, was World War I (1914-1918). The scientific community, though, worked around the war and Einstein’s papers eventually wound up in the hands of Sir Arthur Stanley Eddington, head of the Cambridge Observatory in England. Eddington would be one of Einstein’s greatest supporters and explainers of his complex theory.
To tell the story of Einstein, Eddington and the 1919 solar eclipse, I wrote ECLIPSE: How the 1919 Solar Eclipse Proved Einstein’s Theory of General Relativity. It launches on October 8 and is now available for preorder.
Push and Pull: Explaining General Relativity to Kids
How do you explain general relativity to kids? I studied the NextGen Science Standards for inspiration and was thrilled to discover that even kindergartners study PUSH and PULL.
K-PS2-1 Motion and Stability: Forces and Interactions: Plan and conduct an investigation to compare the effects of different strengths or different directions of pushes and pulls on the motion of an object.
I realized that in Einstein’s theory PUSH would equal acceleration and PULL would equal gravity. By using the simple terms of PUSH and PULL, the theory became within reach for a children’s picture book.
The story follows Stanley Eddington to Africa into the path of totality for the 1919 solar eclipse. They carried a large telescope with them in hopes of photographing the eclipse. Before leaving England, they took NON-ECLIPSE photos of the Hyades star cluster. In Africa, they took DURING ECLIPSE photos to compare. If the Hyades star cluster appeared to move, it would be proof that the star light had bent around the sun.
It was a tricky and expensive expedition. The Principe Islands were known as the Chocolate Islands because they grew and exported cacao for major chocolate manufacturers such as Cadbury. Other than commercial exports, though, there was very little traffic to the island. Once there, the tropical climate made development of the film difficult. And there was the weather.
The eclipse would occur about 1:30 pm on May 29. The morning started with storms, so cloudy that no one could see the sky. About noon, it started to clear, but slowly. Finally, just as the eclipse started, the clouds parted.
Fortunately, a second team of astronomers had gone to Brazil, the other location that would experience a total eclipse. They, too, had problems. Their main telescope warped in the heat and moisture, making all images blurry. They used a back-up 4″ telescope to take the picture, the best pictures of either expedition.
Photos Proved General Relativity
Then, the hard work began. After the photographs were safely returned to the observatory in England, the measurements and calculations began. And it was complicated! The math had to account for Earth’s atmosphere, the gravity of Earth and the sun, temperature variations and more. But finally…
On November 6, 1919, Stanley and the other astronomers presented their results. The starlight had appeared to move. That meant the sun’s gravity had bent the starlight–which proved Einstein’s theory. The 1919 solar eclipse had changed the world forever.
Watch the Eclipse in the FlipMe Feature
If you can’t see this video, CLICK HERE.