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Q & A: gravity and curved space

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Most recent answer: 04/09/2016
Q:
Dear Physicist: i am curious about gravity vs. curved space. Is gravity holding Earth in its orbit or is it merely following curved space. Why don't we quantify an orbit by its curved plane or angle of deflection instead of attractive force? Do they exist together? Forgive my ignorance and I hope you can set me straight . Sincerely Allan Ward
- Allan Ward (age 58)
Meriden, CT 06451
A:

If you want a fully accurate theory, you do need to use the curved spacetime picture of General Relativity. So the Earth is just following a geodesic path in that curved spacetime, with the curvature being caused by the massive Sun.

You can get a very close intuitive description by imagining that we live in plain Euclidean flat space with time flowing at a uniform rate  everywhere. In that picture, if you want to account for the Earth's orbit you have to say that there's a gravitational field from the Sun causing the Earth to accelerate toward the Sun.

So these are two different ways of looking at the same thing, but one way is a little more accurate.

Mike W.


(published on 04/09/2016)

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