A river delta, one stride wide

recreated every tide

For some time I had two websites in my name (as well as a few others dedicated to specific topics and businesses). One of them is this one, the other is/was royeveritt.com, and there were quite a few articles on there that no one could see any more because I had a redirect on that domain to this website.

Anyway, I decided to rescue them and have posted most of them on this site, under ‘Articles’, would you believe. You may find them useful or thought-provoking. I’ve dated them approximately to their original date but they are, of course, timeless 😉

They’re all written by me so please don’t even think about republishing them without my permission, though of course you’re welcome to link to them,

Roy

Gauss pioneered a branch of mathematics called non-Euclidean geometry, and an example of this is geometry drawn on the surface of a sphere, such as the Earth.

If we draw a triangle on a flat surface, the sum of the angles in the triangle is always 180 degrees. But if we draw it on the surface of the Earth, this is no longer true. To visualise this, imagine a triangle where one point is at the north pole and the other two corners are on the equator. Two of the sides are thus lines of longitude and the angles they make with the equator are both 90 degrees. Thus, whatever angle we have at the pole, the sum of the angles is greater than 180 degrees…

But ‘whatever angle we have at the pole’ includes anything from a fraction of a degree to almost 360 degrees, and that includes 180 degrees, or a straight line. Thus, our triangle now has one continuous side, from equator to equator, via the pole, and one side along the equator.

Making two sides. (Of equal length, if the Earth is a perfect sphere.)

Meanwhile, angles at the pole greater than 180 degrees give us some really weird triangles that emphasise the impossibility of drawing a non-Euclidean shape on a flat, Euclidean surface.

Just a passing thought.

See what I did there? Here’s a little poem I wrote in January 2015 that I just rediscovered among my emails:

No age but the mileage,
no miles but the ride
past the edge of the village
to the turn of the tide.

Old guys get the go on
to ride on ahead.
No age but the mileage:
the miles in your head –

the miles put behind you,
the miles still to ride.
No age but the mileage.
No miles but the ride.

Roy Everitt 2015-17

Almost three years later, it’s still true 🙂