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How far does gravity's influence extend?

I've recently (re-)seen 'The Universe' season 1 where it's said that 'take these two dice, place them perfectly still in empty space 1 inch apart and within an hour they'll touch due to their gravitational attraction'.

I get the explanation and it makes sense.

Imagine a universe that has NOTHING AT ALL in it (except the properties of spacetime as we know it, static (therefore devoid of dark energy/matter) and the two die (dice)) - placed an inch apart, they'd eventually touch, a metre apart would they still eventually touch? a kilometre? A mile? A light year? xxx light years?

i.e. if there were no other gravitational influences, would the dice eventually touch if they were placed at opposite sides of the visible universe (given that the extended un-visible universe were also devoid of any mass)?

I believe yes as Newtonian physics states the attraction is the inverse square of distance - the attraction would be almost infinitely small, but surely there would be some and would take 'some time' to touch.

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Well, in your very ideal system and from the classical point of view, yes the dices (considering they as an electromagnetic neutral system) will be in touch at some time independent of where are they at the beginning.

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  • $\begingroup$ It's a thought experiment (or perhaps a proposal) just as Einstein did in his 20's with the clocks. $\endgroup$ – Ken Alton Apr 11 '16 at 19:38

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