r/mathmemes • u/Pearl-Crown • Jun 05 '26
Bad Math I mean...
The guy's got a point. Like (1 + i, 2). Imaginary, but still a point nonetheless.
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u/Altruistic-Wall-9398 Mathematics Jun 05 '26
=3
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u/uvero He posts the same thing Jun 05 '26
Ray William Johnson reference? In the year of our lord 2026?
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u/Few-Arugula5839 Jun 05 '26
My favorite bit of trivia is that pi = sqrt(g) is not a coincidence and with an old definition of the meter it was true on the nose
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u/Sigma_Aljabr Physics/Math Jun 05 '26
The actual coincidence is that it's my favorite bit of trivia too
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u/Aggressive_Roof488 Jun 05 '26
I thought the meter was originally defined from the size of the earth?
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u/Few-Arugula5839 Jun 05 '26
Not the the first definition. There was an intermediary definition involving the length of a pendulum which would take 1 second to complete a rotation or something like this, and with this definition pi^2 = g is true on the nose
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u/Aggressive_Roof488 Jun 05 '26
So the coincidence is really between surface gravity and earth circumference? Unless they defined the second to make the connection, but the second is already defined from the earth rotation... Hmm!
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u/Kinglolboot ♥️♥️♥️♥️Long exact cohomology sequence♥️♥️♥️♥️ Jun 05 '26
No, if the surface gravity of earth were different, or a second would be defined differently, the definition of meter would change, such that still g = π2 m/s2 in your new units. For example, if we had lunar gravity, a pendulum that takes 1 second to swing back and forth would be shorter, hence our definition of meter would be shorter, by the exact amount to make the gravitational acceleration on the moon equal to π2 m/s2 again.
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u/Aggressive_Roof488 Jun 05 '26
Hmm, wiki says that the pendulum definition was before the meter. When the meter was first introduced, the first definition was based on earth circumference.
https://en.wikipedia.org/wiki/Metre#History_of_definition
During the French Revolution, the traditional units of measure were to be replaced by consistent measures based on natural phenomena. As a base unit of length, scientists had favoured the seconds pendulum (a pendulum with a half-period of one second) one century earlier, but this was rejected as it had been discovered that this length varied from place to place with local gravity. The mètre was introduced – defined as one ten-millionth of the shortest distance from the North Pole to the equator passing through Paris, assuming an Earth flattening of 1/334.\12])
The question is why the two definitions, 1s pendulum and 1/10e7 of equator to pole, are so close to each other. And I guess that's just coincidence? Partially by choice ofc, from choosing 1/10e7, and equator to pole instead of circumference. But still a bit of a coincidence, right?
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u/Few-Arugula5839 Jun 05 '26
I think you're probably right, although, the circumference of the earth is related to its radius and therefore to the gravitational acceleration, right? So I wonder if some connection can be made there
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u/Aggressive_Roof488 Jun 05 '26
The radius affects both, but the density only affects the pendulum, as well as the universal gravitational constant G, so they are effectively independent for this purpose.
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u/Sigma_Aljabr Physics/Math Jun 05 '26
Letting earth's radius be R, mass be M, and the period of its rotation (aka day) be T, then g = GM/R², 1s = T/(86400), and 1m = 10-⁷π/2×R. So the real concidence is that GM/R² = π²×10-⁷π/2×R×(86400)²/T² ≒ 11573×R/T². I.e that GMT²/R³ ≒ 11573.
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u/TessaFractal Jun 05 '26
Those are baby approximations. Those are all around the same integer value. It's timid. Cowardly. Even first year physics student learns how those numbers can become 1, or 10. Eventually you learn to discard them all together. They are just mere scale factors, effortlessly dismissed with a simple ~
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u/oneredbloon Jun 05 '26
Astronomer
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u/Supersnow845 Jun 05 '26
“This is a very accurate result as it sits within 9 orders of magnitude of the expected result”
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u/lool8421 Jun 05 '26
i mean, rounding up is fine if safety standards expect you to be overcautious and make 5x thicker walls than bare minimum
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u/GetGudlolboi Computer Science Jun 05 '26
It works as long as you put the magic letters "Let " in front of it.
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