
Stones and Apples - oxplot
https://blog.mathspace.co/stones-and-apples/
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surfsvammel
This was awesome. I’ve taken astronomy and physics in high school and then
later physics and mechanics at university. But this article explained gravity
way better than anything I’ve encountered before.

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kazinator
The viewpoint presented in the article looks "way better" only because you've
been exposed to it much more recently than what you've studied in the past.
Newer = shinier.

Also, you've not been asked to solve any chapter exercises using this shiny
theory, where you have to obtain correct numerical answers.

Ash and Bernard crawling from the apple's equator to its stem is cute, though.

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sp332
This is a great mental model, but I'm getting hung up on a more minor point.
The masses wouldn't be moving around on a static spacetime model because, as
the text says, the masses are what bend the spacetime. So spacetime would be
more curved close to each mass, which in turn means they would accelerate
toward each other even harder as they got closer to each other.

~~~
kazinator
Curved spacetime is not required to explain anything in classical mechanics.

The presented concepts are poorly developed and do not account for forces
other than gravity. Suppose A and B are oppositely charged and
electrostatically attracted together with great vigor over a considerable
distance. Next to A there is a C, which is not charged, and not attracted to B
(other than mildly due to gravity). A begins to move toward B rapidly, whereas
C hardly moves toward either of them. Are A and C situated in a differently
curved spacetime, even though they start off right next to each other in both
space and time?

You didn't learn it this way in school because it's bunk. The equations of
motion together with fields that are responsible for forces provide a coherent
theory that actually solves problems.

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billiam
It's....complicated. That's why The Three Body Problem is not just a great
scifi book, but a real mechanics brain teaser. That doesn't take away from the
strength of this illustration, which is explanatory in nature, not
authoritative.

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zeckalpha
These diagrams look upside down to me. I think of gravity Wells like those
coin donation wells:
[https://i.pinimg.com/736x/1e/c8/de/1ec8de8c6c3d15ff0df8cafa8...](https://i.pinimg.com/736x/1e/c8/de/1ec8de8c6c3d15ff0df8cafa87bbfa6d.jpg)

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nerdkid93
MinutePhysics on YouTube was the first place I saw a good explanation of
spacetime curvature, but this write-up is equally good.

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Jupe
Very interesting read... I wonder at what distance the expansion of the
universe itself nullify the gravitation attraction?

