The equivalence principle provides the solution to newton's spinning bucket. in otherwise empty space the center of gravity the combined bucket of water would be near the relative center the combined masses. as the bucket spins it acquires energy( and therefore increases its mass) the combination the change mass along with the acceleration of the bucket produces the same effect as a gravitational field drawing all of the water in the bucket to the sides if the buckets spin is great enough to exceed the strength of the gravitational field previously drawing the mass toward the center of the water. as the bucket spins it draws the outer atoms of water closest to it first do to the cosmic speed limit imposed by relativity and proximity to the bucket. as the the acceleration is transferred to more and more molecules of water it drawn to the bucket and more and more of the water participates in the accelerated motion of the bucket. due to the electromagnetic and strong forces, the the density of the water (as well as it's shape) clinging to the bucket and the bucket prevent the their combined mass to collapse into donut shaped black hole unless the bucket can be accelerated to a velocity that mimics the strength that general relativity requires to produce a black hole. christina knight