Tuesday, 13 February 2018

Is the Earth Flat?

Some people are still arguing about whether the Earth is round or flat.

I once did an experiment to try to prove that the Earth is round. The date was Sunday, 8th May 2016. My experiment failed, as I’ll relate in due course.

Here’s the idea. You visit a high hill, adjacent to flat country. You go there on a day when the visibility is perfect. You take your camera, and if you have them some decent binoculars.

You walk (slowly!) up the hill, and once you’re clear of any buildings between you and the plain, you measure how far you can see. Not to church steeples, but to objects close to the ground – like cows. You do it at several different heights above the plain. Then you plot how far you can see against how far you are up the hill.

Now if the Earth was flat, how far you can see wouldn’t depend on how high you are up the hill. With perfect, unobstructed visibility, you could see a cow 5 or even 10 miles away across the plain as soon as you could see one 1 mile away.

If the Earth was round, on the other hand, you’d expect to be able to see further the higher you are up the hill. I’ll leave out the trigonometry, but you’d expect the distance you can see to be very close to proportional to the square root of how far you are up the hill. Otherwise put, if you’re four times as far up the hill, you should be able to see twice as far.

Anyway, the hill I picked for my experiment is called the Worcestershire Beacon. Its top is almost 1,400 feet above sea level; and about 1,200 feet above the plain to the east, which includes the spa town of Malvern.

It was a beautiful walk. The east side of the hill is steep, so I climbed it from the north. And as I went down the easy south side, gradually losing altitude, I took many photos of the plain.

Imagine my chagrin, then, when I found on reaching the pub at the bottom of the track (the Wyche Inn – I recommend it), that my camera had run out of memory. And that all my photos had disappeared into the great byte sink in the sky.

But what if my photos had come out? Would I have been able to present incontrovertible evidence, even if only to those whose eyes are far better than mine, that the Earth is round?

No. For all I set out to do was to adduce evidence to verify one prediction of the hypothesis that the Earth is round. Namely, that how far you can see over a level plain is proportional to the square root of how high up you are above that plain. I didn’t even manage to do that. And let’s not even think about whether in some places the planet might be “locally round,” and in others not.

Science, when it advances, advances one failed experiment at a time.

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