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I don’t mean that I find the Bernoulli explanation non-sensical — that’s a very common thing these days — more that the experience of listening to the falsehood presented as truth by so many people now means I am suspicious of other non-intuitive explanations.
In this specific case, I can’t get a good intuition about how tidal forces explain (1) Earth’s moon causing ocean bulges on both sides of Earth; and (2) tidal friction making Earth’s moon stop spinning and move further away. I feel like it’s one of those phenomena, like aerofoil lift, whose explanation is glossed over far too quickly given how odd the explanation is.
This is an amateur’s explanation and I’d welcome input from someone with more understanding. For tidal friction, I can’t answer at all, I need to research.
Tidal forces are fictitious forces that are what orbital mechanics look like in the accelerated frame of reference of the thing doing the orbiting. They are not a uniform "pull" in a single direction. That will get you to the idealized Waterworld explanation of PBS SpaceTime. What will get you further is the realization that PBS SpaceTime is almost on-point with the "assume a perfectly spherical cow" joke, which is where the Physics StackExchange explanation comes in, with the reality that the water is moving around and over the rock and that it's a lot more complex.
Which then gets you to Tom Scott and part of Cornwall rising and falling twice per day. (-:
As for the Bernoulli explanation for lift.. try holding a sheet of paper in front of you, it's not solid so it'll bow down, with a nice wing-shaped form. Then blow gently over it, see what happens.
So everything is pulled towards the moon, but the more distant parts are pulled less, and the sides are pulled inwards, so the resultant shape is the familiar ellipsoid
[1] http://nicholasbsullivan.com/page_oceanography/Meeting6/01_t...
That's not really a thing, and tides are way more complicated than that. For example, at any given moment, part of New Zealand's coast is at high tide, and part is at low tide. Same with the coasts around the North Sea, and the Atlantic coast of Patagonia, and Hudson Bay.
Animation of today's tides: https://www.tpxo.net/
Some good tide explanation: http://physics.stackexchange.com/questions/121830/does-earth..., discussed three months ago https://news.ycombinator.com/item?id=44065458
Try to imagine that all the Earth is liquid, so no landmass that resist deformation. And now ask yourself a question: which form this Earth should take in presence of Moon? You see the reason for a bulge facing the Moon, but what kind of shape should be the other side? Anti-bulge, depression? Or maybe an approximate spherical surface? Or another bulge facing from the Moon?
> tidal friction making Earth’s moon stop spinning and move further away.
Deformed Earth is rotating and the bulge under the Moon tends to move faster than Moon (in terms of angular velocity). So the bulge is sort of "in front" of the Moon and it pulls it forward speeding it up. The other bulge works in opposite direction, but it is more distant so the force is lower.
Interesting! I had never caught that key idea and need to read more about that. thanks
With water and surface tension the net result is an oblong oval ish shape
And the tides are basically a teeny tiny version, where the spherical earth water is squeezed to an oblong shape
If it is an asteroid belt, maybe it is on a different (high inclination) plane, which is why the star only hit one part of it.
wglb•4mo ago