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Comment by rcme | Hacker News Reader

What about flipping bits in a processor? Current processors do produce waste heat, but I don't think all of the energy in a processor gets converted to heat and it's not a requirement for computation that heat be generated, e.g. if we had superconducting processors.

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It's not necessarily a requirement (see reversible computing), but we're very far from knowing how to do it if indeed it's possible at all. current processors do convert all of the energy they use into heat. To set a transistor one way, you put a bunch of charge onto its gate. To set it the other way, you take those electrons and dump them to ground. All of that current flowing is converted to heat.

Actually, it is a physical requirement that erasing information generates waste heat. https://en.wikipedia.org/wiki/Landauer%27s_principle

We're still pretty far from that limit, but unless your plan is to never erase bits, you're going to waste energy.

> On the other hand, recent advances in non-equilibrium statistical physics have established that there is no a priori relationship between logical and thermodynamic reversibility.[19] It is possible that a physical process is logically reversible but thermodynamically irreversible. It is also possible that a physical process is logically irreversible but thermodynamically reversible. At best, the benefits of implementing a computation with a logically reversible system are nuanced.[20]

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