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| Argument from computation SupportiveArgument1 #112153 Memory formation in a computer can only occur within an environment where entropy is increasing AND the process of memory formation in human brains is relevantly similar to that in a computer. | In the citation from Stephen Hawking below, he argues that computer encoding of memories requires an increasing entropy gradient. He does not explicitly defend the analogy between human and computer memories. In the subtree of this node, the two co-premises are separated and more formal attempts to make the case are cited.
The second cited paper, by David Wolpert, makes the case that Landauer's Principle is applicable to human memories - at least memories analogous to a photograph on a piece of film - but NOT to computer memories. This version of the argument does not require the co-premise asserting the two are analogous. |
+Citations (2) - CitationsAdd new citationList by: CiterankMapLink[1] The Illustrated Theory of Everything (book excerpt)
Author: Stephen Hawking - Cosmologist
Cited by: Peter Baldwin 9:54 AM 24 June 2011 GMT
Citerank: (1) 112155Computer memories need increasing entropySeveral authors have argued that computer memories require increasing entropy. The cited article from Stephen Hawking is one. A more formal statement of the case by L.S. Schulman is also cited. Schulman's paper appeals to Landauer's Principle that ties information storage to increasing entropy.22FF97FF
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| | Excerpt / Summary The Psychological Arrow
"It is rather difficult to talk about human memory because we don't know how the brain works in detail. We do, however, know all about how computer memories work. I shall therefore discuss the psychological arrow of time for computers. I think it is reasonable to assume that the arrow for computers is the same as that for humans. If it were not, one could make a killing on the stock exchange by having a computer that would remember tomorrow's prices.
A computer memory is basically some device that can be in either one of two states. An example would be a superconducting loop of wire. If there is an electric current flowing in the loop, it will continue to flow because there is no resistance. On the other hand, it there is no current, the loop will continue without a current. One can label the two states of the memory 'one' and 'zero'.
Before an item is recorded in the memory, the memory is in a disordered state with equal probabilities for one and zero. After the memory interacts with the system to be remembered, it will definitely be in one state or the other, according to the state of the system. Thus, the memory passes from a disordered state to an ordered one. However, in order to make sure that the memory is in the right state, it is necessary to use a certain amount of energy. This energy is dissipated as heat and increases the amount of disorder in the universe. One can show that this increase of disorder is greater than the increase in the order of the memory. Thus, when a computer records an item in memory, the total amount of disorder in the universe goes up.
The direction of time in which a computer remembers the past is the same as that in which disorder increases. This means that our subjective sense of the direction of time, the psychological arrow of time, is determined by the thermodynamic arrow of time. This makes the second law of thermodynamics almost trivial. Disorder increases with time because we measure time in the direction in which disorder increases. You can't have a safer bet than that." |
Link[2] The Second Law, Computation, and the Temporal (a)symmetry of Memory
Author: Wolpert, David H. - Santa Fe Institute
Cited by: Peter Baldwin 7:18 AM 2 August 2011 GMT
Citerank: (1) 114661Computers not bound to Landauer's PrincipleIn the cited paper David Wolpert argues that human brains and computers are fundamentally different. Computer memories are not bound to Landauer's Principle but human memories are. Wolpert's version of the argument renders the computer/brain analogy both invalid and superfluous.13EF597B
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| | Excerpt / Summary Many studies have investigated the relations between various aspects of the different arrows of time. Most of these studies take it as a given that the psychological arrow of time derives from
the thermodynamic arrow of time i.e, from the second law of thermodynamics). Yet until now no mathematical proof of this connection has been offered. This has allowed some to even go so far as to make the claim that the two arrows of time are not related at all .
Without reducing the psychological arrow of time to a mathematically well-defined phenomenon, there is no way to rigorously prove (or disprove) a relation between the psychological arrow of time and the thermodynamic one. Here and in [20], the "mathematically well-defined phenomenon" is taken to be the human ability to remember the past but not the future. In short, it is presumed that there is no aspect of the psychological arrow of time which can not be explained by the asymmetry of human memory.
This paper is an overview of an analysis of memory systems and their relationship with the second law. (The full analysis can be found in [20].) This analysis shows that the asymmetry of human memory is a direct reflection of the asymmetry of the second law. In this way it explains why the future is both the temporal direction into which "information is dissipated" (due to the second law) and the direction into which "information is preserved" (via our ability to remember the past but not the future). The implication of this analysis is that if the second law "went the other way", then we would remember the future, not the past and the psychological arrow would point towards the past not the future.
The analysis reviewed in this paper also shows that memory in (abstract) computers need not be directly affected by the second law. Consequently, such memory can infer the future as readily as the past and possesses no psychological arrow of time. This is in accord with the well-known reversibility of computation |
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