I didn't know they already had machine learning and model fitting algorithms in the 1800s, but here we are...
Intuitively you would think that the tide is being formed because the Moon is "lifting up" the water at the point closest to the Moon. But this contribution is actually very miniscule to the tidal effect. Instead the bulk of the tides are produced about 45 degrees away where the tidal force is parallel to the Earth's surface. This has the effect of dragging the water closer to the tidal bulge.
the water of an incoming tide doesn't feel "i'm being dragged uphill", it feels "hey, the earth is moving underneath me". it's all in freefall all the time.
you don't feel like you are rotating at 1000 mph (1600 kph) but you do feel your weight against the surface of the earth. same with the water, except it feels itself being squeezed by everything around it like you only feel that in the entrance to a crowded venue.
so, the water on the side toward the moon and the water on the side away from the moon would mostly perceive the earth as dropping away or coming closer (if they could perceive anything at all) where they are is always their point of reference
In particular, I could understand how two satellites connected by a cable would result in the cable being stretched. But I still find it hard to wrap my mind around the fact that we get a high tide where the Earth's gravity and the Moon's add (the far side of the Earth from the Moon), but we also get a high tide on the opposite side, where the Moon's gravitational pull is subtracted from the Earth's. The centrifugal force is (I think) a much better explanation. (I realize physicists don't consider that a force, but...)
So yes, tides really are weirder than I think.
(The other facts in the article were actually familiar, e.g. the fact that the tides in Hawaii are quite small, because it's not far from an amphidromic point.)
Basically, a summation of sinusoids.
For me, the worst are posts about scale and things I won't need, like "You don't need kafka" or "your data isn't actually big data" or "don't horizontally scale, just get a bigger server"
I get that I am not the target audience and there are people for whom those statements are true, but I am running Kafka clusters with data from 10s of thousands of servers, I absolutely can't move that to a single machine.
I wish they would phrase it as "Tides are weirder than most people think", although that probably doesn't drive as much engagement.
It is language quirk, but you can probably use LLM to replace HN headlines like this. Pretty cheap and one will no longer have visceral reaction that one does not wish.
Any talk of tide prediction should always mention xtide:
I've used it with great accuracy in a number of locations around the world.
Another one of those free software packages that's been meticulously maintained by one person for decades...
Title: The Most Powerful Computers You've Never Heard Of
