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When you think about it, the amount of necessary prior knowledge is massive. You have to know that planets have an elliptical orbit. Except for Mercury, all f
by yongjik 5y ago
When you think about it, the amount of necessary prior knowledge is massive. You have to know that planets have an elliptical orbit. Except for Mercury, all five classically known planets (and the Earth) have eccentricity of only a few percents (and Mercury is pretty hard to observe), so you need someone (that is, Tycho Brahe) who could spend years looking at the night sky, recording the precise location of each planet, enough math for someone to match it to an elliptical orbit observed from another (= Earth's) elliptical orbit, and a society that can support such a "useless" hobby.
- wolverine876 5y agoSomeone else brought up planetary orbits as a prerequisite. Is there no other way to work out the laws of gravity? Again, we're talking about 200,000 years. But yes, there's the larger point that Newton also needed mathematics and other things. And the laws of gravity might not be the perfect example of my point, but my point isn't about Newton or gravity.
- deleted 5y ago[deleted]
- simonh 5y agoI think there's no other way. You have to observe the fact that the attractive force obeys the inverse square law. That's not measurable with experiments here on earth without extremely advanced modern instruments, so that makes it's effects only really observable on the motion of astronomical bodies. Historically this was the observation that orbits follow elliptical paths. Absent that you'd need some other observation that would lead you to the same conclusion.
- wolverine876 5y agoVery insightful hypothesis, thank you.