At the bottom, it's all an increase in entropy. That's my standard answer, probably informed by my college studies (Physics, not CS). The layers on top might b

At the bottom, it's all an increase in entropy. That's my standard answer, probably informed by my college studies (Physics, not CS). The layers on top might be different, but at the very bottom of things, it's always entropy "trying" to increase. That's why computers eventually break, that's why living things age and die. To counteract this tendency, you'd have to somehow prevent the entropic increase within each system. Technically doable, but the devil is in the details. Life itself fights entropy, the problem is that whatever anti-entropic mechanisms it employs, they're not stable long-term, at least not for pluricellular organisms as separate systems. The biosphere as a whole has actually been remarkably resilient so far.