B How Much Mass Required to Demonstrate Gravity?

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To demonstrate gravity independent of Earth's influence, an experiment would need to occur in space with sufficient mass to be observable by the naked eye. A minimum mass comparable to that of a planet is necessary for visibility, as smaller masses would not create a noticeable gravitational pull. Historical methods, like the torsion balance used in the Cavendish experiment, highlight the challenges of measuring gravity accurately. Two 10kg masses, if positioned 1 meter apart and initially at rest, would collide within approximately 8 hours, but achieving such precise initial conditions is complex. Ultimately, demonstrating gravity in this manner requires significant mass and careful arrangement to be effective.
Roman Mithman
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If one were to demonstrate gravity independent of earth's constant gravity, how could it be done? Assuming this would need to be done in space, what minimum proportions of mass would be required to demonstrate gravitational pull to a human's naked eye?
 
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Two 10kg masses 1m apart in space and initially at rest would collide fairly quickly. Setting ##s=\frac 12\frac{GM}{r^2}t^2## gives an upper bound of about 8 hours (remembering each mass only needs to travel ##s=0.5\mathrm{m}##).

Of course, you need to arrange that the masses are initially stationary to better than 0.01mm/s, which is non trivial.
 
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If it needs to be in space, far from the earth, and you need to see it with the unaided eye, it needs to be at least planet-sized. (Note that this is independent of measuring gravity)
 
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