Comment by Scared-Ad-3841 on 22/06/2022 at 15:58 UTC

2 upvotes, 1 direct replies (showing 1)

View submission: Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science

imagine two heavy spheres connected by a string, floating in empty space: there would be tension on the string depending on their rotation around their center of gravity.

if they would be the only two masses in the whole universe: what would happen ? How could they 'know' about their rotation relative to nothing ? would the masses 'define' properties of space, or is my question just flawed ?

Replies

Comment by Weed_O_Whirler at 22/06/2022 at 18:31 UTC

6 upvotes, 1 direct replies

They could tell, because rotation is an acceleration and accelerations can be sensed.

Think if you're in a chair, close your eyes, and you get spun in a circle. You'd be able to tell you started spinning, right? Your arms would want to move up, if you spun fast enough you'd get light headed. Because spinning is acceleration, and accelerations can be sensed.