In current physics, potential energy is energy based on position in a gravitational field, so raising an object stores potential energy that is returned later when it falls. This balances the ledger, so energy isn’t lost or made, but what stores and releases potential energy?
It is easy to forget that potential energy is a concept not a thing observed, so if a rocket is shot into earth orbit, where the liftoff energy goes isn’t seen. If the rocket leaves the earth and travels in space forever, presumably its potential energy is stored forever. If it later crashes on a bigger planet like Jupiter to release more energy than leaving earth took, where does the extra energy come from? Energy is conserved if objects stay in the same place but they never do, so is potential energy just a fudge to make up any differences?
Those who explain physics say that energy is conserved because if the Jupiter rocket was re-assembled and returned to earth the energy would be restored. But how can future options explain the present? Imagine applying that logic to entropy, saying a cup broken on the floor has “potential entropy” because it can be reassembled again! One would ask, where is this potential entropy stored? So is potential energy stored in space, matter or gravity itself? Current physics can’t say.
Most energy conservations have a means, so when a car’s kinetic energy is lost to friction its tires become hot and radiate thermal energy. We can observe the kinetic energy turning into energy in the form of heat. In contrast, a ball thrown up loses its kinetic energy to where? With no means of energy exchange, one could argue that potential energy just a way to pretend that energy is conserved when it isn’t. So is energy really always conserved?