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Eclipse 2017: Was Einstein Right?

While most people who make the trek to the path of totality for the Great American Eclipse next week will fix their gazes skyward as the heavenly spectacle unfolds, we suspect many will attempt to post a duck-face selfie with the eclipsed sun in the background. But at least one man will be feverishly tending to an experiment.

On a lonely hilltop in Wyoming, Dr. Don Bruns will be attempting to replicate a famous experiment. If he succeeds, not only will he have pulled off something that’s only been done twice before, he’ll provide yet more evidence that Einstein was right.

Eddington’s Expedition

Back in 1915, Albert Einstein first presented a set of field equations he had been working on for eight years. After publishing his Special Theory of Relativity, he searched for ways to work gravitation into his new framework, and finally hit upon a set of nonlinear and fiendishly difficult equations that describe how space and time must curve under the influence of matter and radiation.

Arthur Eddington. Source:
Wikimedia Commons

The physics community took a keen interest in Einstein’s General Theory of Relativity and began looking for ways to prove it. One of the predictions of the theory is gravitational lensing, or the deflection of light by massive bodies (lensing is also a prediction of Newtonian physics, but Einstein’s field equations predict about twice the deflection of light as the classical model). Measuring this effect, though, is no mean feat, mainly because the one thing massive enough and close enough to quantifiably bend light also happens to be really bright itself — the Sun.

What was needed was a total solar eclipse, and conveniently enough, one would occur in May of 1919. With only four years to go, and with the world torn by war, Sir Arthur Stanley Eddington planned a scientific expedition to the island of Principe off the west coast of Africa. He took a series of photographs of stars in the Hyades cluster, and through careful measurement found that Einstein’s predictions were correct. The publication of his results the next year made a huge splash in the popular press, instantly catapulting Einstein into the public eye and…

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