Why this eclipse could really prove Einstein was right

EL SALTO, Mexico — Three hours before the total solar eclipse, the sky had only a few wispy clouds.

“It looks good,” said Toby Dittrich, a physics professor at Portland Community College.

For him, the eclipse isn’t about the pictures of an occulted sun. Instead, he wants to use the celestial phenomenon to understand our universe like never before.

Dittrich and a group of students are planning to run one of the most famous astronomical experiments in history — one that proved Albert Einstein’s theory of general relativity. It showed how our massive sun bends starlight around it, showing that space-time must be curved instead of flat as Isaac Newton had predicted. Since it was performed with rudimentary instruments in 1919, though, scientists have run only a limited number of loose follow-on tests.

Dittrich wasn’t satisfied. “No one really believes that [Einstein’s theory] isn’t true because of theoretical calculations,” he said. “But no one has actually satisfactorily proven it.”

So instead of heading to sought-after eclipse-viewing destinations such as Mazatlán, Mexico, or Austin, Dittrich and a group of fellow physics professors, amateur astronomers, and undergraduate students traveled more than 2,000 miles to the outskirts of El Salto, a small mountainous town in northcentral Mexico.

This remote area is at the center of the eclipse shadow, providing 4 minutes and 30 seconds of totality — the maximum time that anyone will experience during this eclipse. It might also shed unprecedented data that would verify Einstein’s mathematical model without a doubt.

The journey of Dittrich’s 2024 experiment began more than a century ago. A 36-yearold Einstein, yet to reach major stardom, published a radical new idea in 1915 on how gravity worked.

Previously, Newton proposed that gravity occurred in a flat, uniform space. But in Einstein’s universe, space and time (which are inextricably linked together) are curved, getting pushed, pulled, stretched, and warped by matter.

“If you get really close to really massive things, things get weird,” said Daniel Borrero Echeverry, a physics professor at Willamette University in Salem, Ore., who also traveled to El Salto.

Einstein did the math to prove his theory, but he suggested one way of measuring it in the real world would be by recording the position of the stars close to the sun when the sun is out and compare it with when it’s absent. It’s difficult to image stars in daylight because the sun washes them out, though — unless a total solar eclipse blocks the sun’s surface, allowing scientists to see details along its outer edge.