alt Hacker News> Caused by different densities of rock far beneath Earth's surface, these variations in gravity are small in absolute terms. But they can have particularly large effects on the oceans. Where gravity is weaker, the ocean surface can sit slightly lower relative to Earth's center because water flows away toward areas of stronger gravity. Due to its gravity hole, the sea-surface height around Antarctica is measurably lower than it would otherwise be.
Isn’t that just a result of earth rotation, and not some magical rocks far beneath earth’s surface!? Plus, that’s not how gravity works anyway, this sounds like some high school way to explain gravity.. in fact, no one knows what gravity is, even quantum physics can’t explain gravity.
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There are a lot of rocks beneath earth's surface, and it shouldn't be surprising or magical that some of them are heavier than others. Which does affect local gravity, especially if we talk about the rocks close enough to the surface.
Take for example a look at https://www.esa.int/ESA_Multimedia/Images/2015/04/Bouguer_gr... which has better resolution than the map in the article and tries to correct for oceans and mountains. There are clear deviations from the norm, and they are not shaped in a way that can be explained by simple rotational effects (even though those also exist)
> it is weakest beneath the frozen continent of Antarctica *after accounting for Earth's rotation*.
Geophysicist here. Look up potential fields methods in geophysics.
Such things have been measured and mapped for quite some time.
The grandfather of all modern gravimeters was invented in 1936 by LaCoste and Romberg.
If you weren't accounting for earths rotation, the area with lowest gravity would be near the equator due to the larger distance to earths center.
> in fact, no one knows what gravity is
Albert Einstein has entered the chat
> Plus, that’s not how gravity works anyway, this sounds like some high school way to explain gravity.. in fact, no one knows what gravity is, even quantum physics can’t explain gravity.
There's an impressive amount of irony in these juxtaposed statements.