On Wed, Dec 17, 2014 at 1:27 PM, Abram Demski via AGI <[email protected]> wrote: > My current understanding of time is "the direction of computation".
That is actually quite precise. The entropy of a computer can only decrease. In a state transition diagram, states can merge but not fork. Operations like writing a bit of memory cannot be reversed because the previous bit was erased. Of course, decreasing entropy would violate thermodynamics unless it increased elsewhere. That is why computation requires energy. To be precise, writing a bit of memory requires kT ln 2 joules where k is Boltzmann's constant and T is the temperature. Quantum computing is time reversible. The energy consumption can be arbitrarily low, but your algorithm has to be able to run backward. In both quantum mechanics and general relativity, the observer plays a central role. We can be precise by what we mean by an observer. It is anything with memory. An observation consists of writing into it. It explains why in physics there are some things we cannot observe. For example, we cannot observe the wave nature of matter and energy. We can only observe particles, which give us uncertain information about the wave. To do otherwise would violate thermodynamics. You cannot reduce uncertainty (entropy) through observation or learning without increasing uncertainty (heat) somewhere else. -- -- Matt Mahoney, [email protected] ------------------------------------------- AGI Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/21088071-f452e424 Modify Your Subscription: https://www.listbox.com/member/?member_id=21088071&id_secret=21088071-58d57657 Powered by Listbox: http://www.listbox.com
