Vladimir_M comments on The conscious tape - Less Wrong

11 Post author: PhilGoetz 16 September 2010 07:55PM

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Comment author: Vladimir_M 17 September 2010 07:58:17PM *  2 points [-]

I don't think your thought experiment is logically consistent. You're using a physical theory, namely special relativity, to discuss a case in which the theory explicitly refuses to say what happens, because it's considered unphysical within that theory.

If the computer moves at exactly the speed of light, and assuming special relativity, the time in which the computer will reach a given step of its program becomes undefined, not "never." In any physically possible case, in which the computer's speed can be arbitrarily close to c, things develop completely normally in the computer's own reference frame.

Moreover, if you observe the code of a program, it's just a string of bits (assuming a binary computer). And a string of bits can be interpreted as implementing any arbitrary program, given an arbitrary choice of the interpreter. Therefore, until an actual interpretation happens, what makes your hypothetical "hell" and "Utopia" essentially different?

Comment author: ciphergoth 18 September 2010 08:09:08AM 2 points [-]

The "speed of light" qualification was a mistake. I was just trying to get the computer out of our light cone somewhere we can never observe it.

Comment author: Nisan 18 September 2010 07:43:51PM 1 point [-]

And a string of bits can be interpreted as implementing any arbitrary program, given an arbitrary choice of the interpreter.

You could discriminate between heaven and hell by considering the minimum length of an interpreting program. Such a program would have to produce output that would be directly comprehendible by us, and it would have to be written in a language that we wouldn't regard as crazy.

In order to see heaven in hell, your interpreter probably has to contain hell.

Comment author: Vladimir_M 18 September 2010 08:30:28PM *  1 point [-]

Fair enough; that's true when it comes to an arbitrary program. However, consider a program that contains both heaven and hell in different branches, and will take one of these different branches depending on the interpreter. Or, alternatively, consider a program simulating a "good" world that will, given some small tweak in the orignal interpreter, simulate a much worse world because some simple but essential thing will be off. Such thought experiments, as far as I see, override this objection.

Comment author: wedrifid 18 September 2010 04:13:42AM 0 points [-]

In any physically possible case, in which the computer's speed can be arbitrarily close to c, things develop completely normally in the computer's own reference frame.

For the right right value of 'arbitrary' the computer never performs a single operation. The entire box is obliterated by collision with a stray electron before the processor can tick. The collision releases arbitrarily large amounts of energy and from there things just start getting messy.

Comment author: Vladimir_M 18 September 2010 07:13:27AM *  2 points [-]

In a thought experiment, you can assume anything, however unrealistic, as long as it's logically consistent with the theory on which you're basing it. Assuming away stray electrons is therefore OK in this particular thought experiment, since the assumption of a universe that would provide an endless completely obstacle-free path would still be consistent with special relativity. In fact, among the standard conventions for discussing thought experiments is not to bring up objections about such things, since it's presumed that the author is intentionally assuming them away to make a more essential point about something else.

In contrast, introducing objects that move at exactly the speed c into a thought experiment based on special relativity results in a logical inconsistency. It's the same mistake as if you assumed that Peano axioms hold and then started talking about a natural number such that zero is its successor. Since the very definition of such an object involves a logical contradiction, nothing useful can ever come out of such a discussion.