For questions like these I sometimes prefer translating everything to thermodynamics. In this case the question then becomes "Why are we looking at energy if a

For questions like these I sometimes prefer translating everything to thermodynamics. In this case the question then becomes "Why are we looking at energy if at most ordinary temperatures systems aren't anywhere near 0 energy?". The overly simplified answer is "Because bowling balls still roll down, even at room temperature." Which is actually kind of interesting to think about. Why do bowling balls roll down when they have vastly more thermal energy than gravitational potential? To get an answer you have to invoke the second law of thermodynamics. Which is annoyingly a bit hard to really get to understand. In short it implies that energy likes to become more disorganised, so something like gravitational potential which is very organised will eventually devolve into heat which is (by definition) disorganised. So bowling ball roll down.