To Newton, what kept his feet on the ground was a new concept called gravity, mysteriously acting instantaneously at a distance; to Einstein, it was a new concept called spacetime, whose local curvatures are affected by local mass, but whose distortions stretch out across the universe, affecting the motion of all other masses. Both are mental models, defying visualisation in terms our minds can properly comprehend. But it keeps the mathematicians happy. . .
Isaac Newton said, “It’s clear:
Forces act from far and near,
Every mass attracts each other, in proportion.”
Said Einstein, “No, not that!
You’re assuming spacetime’s flat,
But around each mass is serious distortion.”
Yet each is just a way
Of explaining things away
Which remain a total mystery for ever.
They are too much for the mind,
Which just limps along behind
While the maths men write equations and look clever. . .