Physically proven

Four minutes. For four minutes, the skies darkened. For four minutes, the birds fell silent. For four minutes, temperatures plummeted. And in those four minutes, the whole order of nature was overturned.

Animals went haywire. NocturnalActive at night and asleep during the day. The term derives from the Latin "nocturnus", meaning "of the night". Its opposite is "diurnal". creatures like owls woke up and flew around, believing it was already night. In a TexanFrom Texas, a huge state in the southern US, next to the Mexican border. zoo, the gorillas loped off to the barns where they usually sleep.

But perhaps the human response was stranger. It is thought five million people travelled to see it.¹ Some cheered, others wept. In ArkansasA southern US state with a population of just over 3 million. , 250 people got a TV singer-songwriter to officiate a mass wedding in the four minutes of darkness.²

It all helps to explain why eclipses left such a mark on traditional beliefs. In VietnamA Southeast Asian country with a population of nearly 100 million. it used to be thought that an eclipse happens when a giant frog swallows the sun and its master, the lord of Hahn, has to persuade him to spit it back out.

For the ancient Greeks, an eclipse was a sign of the gods' displeasure with humanity. As punishment, they took away the sun. Indeed, the word "eclipse" comes from a Greek word that means "abandonment".³

This cosmicRelating to the universe or cosmos. ballet is all the more wondrous when we consider how improbable it is. By sheer coincidence, the Moon is about 400 times smaller than the sun, but also about 400 times closer to the Earth. That means its disc in the sky is exactly the right size to cover our local star.

And that will not last forever. The Moon is steadily moving away from the Earth. That means if human beings had evolved 600 million years later, we would never have seen a total eclipse.⁴

And unbeknownst to the millions looking up in awe, a scientific breakthrough was taking place just outside the small Mexican town of El Salto. A group of physicists had set out to prove Albert EinsteinA German-born physicist, whose work in the early 20th Century revolutionised scientific understanding of the world. right.

It is now generally accepted that space and time exist on a continuum, known as space-time. In general, we think of both as linear. Time moves in one direction and space is on three straight axes: length, width, and height.

What Einstein argued was that space-time can actually curve under the influence of gravity.⁵ That is why near massive bodies, time moves more slowly. Close to a black hole, the most massive objects we know about, you would see your watch ticking more slowly.

Every physicist in the world now agrees with Einstein. But he only ever proved this theoretically.

That is why the scientists in Mexico were there. They hoped to get empiricalThrough observation or experience, rather than just theory. evidence that Einstein's theory is correct.

Einstein stated that according to his theory, the stars around the sun in the sky should appear in a different position when the sun is there from when it is absent. But during the day, you cannot see the stars to verify this. Unless something is blocking it.

It took the team seven years of preparation, and bad weather and a faulty telescope mount almost ruined it. But with four working telescopes they managed to get pictures of 200,000 stars.

Now they hope to use those data to prove once and for all that modern physics is right.

Did it prove Einstein was right?

Yes: Other experiments, with less sophisticated equipment, have already provided some evidence that Einstein's theory holds up in practice. We have every reason to expect this one will too.

No: Experiments never definitively "prove" anything. This may provide useful evidence until someone arrives at the next eclipse with even more telescopes.

Or... It will take some time to analyse all the data the research team collected from the site, and we will not know anything for sure until then. But they are quietly confident they have done something great.