> Would you feel centrifugal forces in an empty universe? Does the law of inertia mean anything in an empty universe? Mach would give a resounding “no” to both

> Would you feel centrifugal forces in an empty universe? Does the law of inertia mean anything in an empty universe? Mach would give a resounding “no” to both questions: Inertia is not a property intrinsic to an object but depends upon all the mass in the universe. If "you" can exist in a massless universe (that which encompass all that exist) - then, by definition, "you" have no mass. So insofar as mass is connected to inertia is connected to angular momentum (the need for acceleration/force to alter the direction of movement) - then: no, you would not be able to detect "centrifugal forces" without any mass. But, if "you" have mass and exist in a universe, that universe consist of at least the mass making up "you". Let's assume a sphere/clump of small magnets. Would it be possible to spin this sphere fast enough for it to disperse - tear itself apart? I would think so.