OT: I'm confused about gravity

Jul 29, 2018 178 Replies
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I remember taking g as 10 (pre-calculator days) at school . This allowed for very easy multiplication but showed if you had applied it correctly. Knew it was 32 ft/sec/sec but even away back then we used SI units of metres/sec/sec (also newtons ,kilograms, litres etc)

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suggest such smart arsery is ill founded ...

From the "Longer answer"

The gravitational force exerted by the Sun on the Moon is more twice that exerted by the Earth on the Moon. So why do we say the Moon orbits the Earth?

Good question. Michelson-Morley and shrinking instruments spring to mind.

But now we know gravity waves exist - what effect do they have on time ?

No, he's thinking of Vernes 'Journey to the centre of the earth'

There's layer upon layer of bad physics there: not

Differnet ball game

We know no such thing.

They are, like gravity itself, hypothetical postulates

Artefacts of a worldview we currently hold to repsrent the world exactly, but of course does not.

You fail to appreciate the subtlety.

That IS doing calculus.

and the

You may as well say you can model the trajectory using string theory and therefore you are doing quantum field string theory. Same for higher dimensional tensors or Riemann space geometry. Where does it end?

Simple algebra is quite sufficient.

Er, did I say algebra? I meant geometry.

Well, if history is anything to go by.....

Sounds about as plausible as Pratchet's stack of giant turtles.

Taking g = pi^2

was an allowable exam approximation in the pre calculator era. In many physics equations there is a pi somewhere else too.

No, there's only one, the Great A'Tuin.

Don't you know any physics?

All of science and maths is implicit in our view of the world

We just unpick it.

No.

I tend to agree. We discover maths not invent it.

I meant geometry but the same parabolic can be modelled in cartesian algebra without calculus.

'Simple' is in the eye of the beholder.

We don't, they both orbit their common centre of mass. It just happens to be inside the Earth (well mostly).

That explains a lot. A quotation from my games teacher: He has no ball control.

Bill

I certainly don't believe in it.

Bill

Because it does according to the definition: Noun: orbit The (usually elliptical) path described by one celestial body in its revolution about another.

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