Does Earth have two high-tide bulges on opposite sides? (2014)
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Does Earth have two high-tide bulges on opposite sides? (2014)
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Re: Does Earth have two high-tide bulges on opposite sides? (2014)
#2I was asked why there are two tides a day in an interview for my undergraduate University place. I blundered through to the classic answer. This stackexchange discussion made me realize I was even more of an imposter than I thought :-).
Re: Does Earth have two high-tide bulges on opposite sides? (2014)
#3I was asked why there are two tides a day in an interview for my undergraduate University place. I blundered through to the classic answer. This stackexchange discussion made me realize I was even more of an imposter than I thought :-).
If it makes you feel better, the crust of the earth does bulge more in line with the classic answer due to the flow of the underlying magma being effectively uninterrupted by solid obstructions. Which then means the classic tidal answer is technically correct, except what we observe as tides is a delta between land and ocean.
Re: Does Earth have two high-tide bulges on opposite sides? (2014)
#4TL;DR newton basically got the FORCES right, but forces don't tell the whole story because of (mainly ) 1) insufficient propagation speed because ocean is deep 2) think of it kind of like a diff eq, the boundary conditions (largely from land masses) from the actual structure of the earth make the solutions much more interesting than F=ma might suggest.
Edit- I recommend actually reading it, especially the second answer.
Re: Does Earth have two high-tide bulges on opposite sides? (2014)
#5So it's a bunch of complicated splashy water that is excited by the moon moving past, and follows along at the same frequency - but it's not a simple wave travelling around the world, for various reasons.
The earth itself is squashed like that with two bulges, but the water on the surface exhibits a more complex motion.
Re: Does Earth have two high-tide bulges on opposite sides? (2014)
#6The problem of predicting tides was so important that it attracted many Physics and Maths heavy weights. You can well imagine how important predicting tides would have been for D-day landing.
One related fascinating historical artifact is the special purpose analogue computer designed by Lord Kelvin in the 1860s based on Fourier series, harmonic analysis. Think difference engine in it's cogs and cams glory, but special purpose.
https://en.m.wikipedia.org/wiki/Tide-predicting_machine
Possibly one of the first examples of Machine learning, with Machine in capital 'M'. It incorporated recent tidal observations to update it's prediction.
Note that sinusoids are universal approximators for a large class of functions, an honour that is by no means restricted to deep neural nets.
George Darwin (Charles Darwin's son) was a significant contributor in the design and upgrade of the machine.
https://en.m.wikipedia.org/wiki/George_Darwin
Other recognizable names who worked on tide prediction problem were Thomas Young (of double slit experiment fame) and Sir George Airy (of Airy disk fame).
Re: Does Earth have two high-tide bulges on opposite sides? (2014)
#7The problem of predicting tides was so important that it attracted many Physics and Maths heavy weights. You can well imagine how important predicting tides would have been for D-day landing. One related fascinating historical artifact is the special purpose analogue computer designed by Lord Kelvin in the 1860s based on Fourier series, harmonic analysis. Think difference engine in it's cogs and cams glory, but speci…
Veritasium made a video on this topic a couple of years ago: https://www.youtube.com/watch?v=IgF3OX8nT0w
Re: Does Earth have two high-tide bulges on opposite sides? (2014)
#8[dead]
Re: Does Earth have two high-tide bulges on opposite sides? (2014)
#9So, yet another thing I learned at school was bullshit. Pretty interesting to know!
Re: Does Earth have two high-tide bulges on opposite sides? (2014)
#10[flagged]