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Journal daniil's Journal: 42? 8

Journal by daniil

It occured to me the other day that Deep Thought lied about the answer to "life, the Universe, everything". When it starts solving the problem, Deep Thought states that it will take seven and a half million years to solve it. After seven and a half million years of computing, DT gives an answer (Forty Two) to the question and states that it's the correct one.

The problem is, however, that (according to an age-old thing called the halting problem) it's not possible to know for sure how long a program will run or if it will ever halt without running it. Therefore, Deep Thought lied about the time it would take to run the program and either hadn't finished the calculation when seven and a half million years had passed, or just made the number up -- but in that case, it could just as well have made up the "answer". In either case, we cannot decide whether the answer is correct or not.

PS: In case you were wondering, then I know that the book is satirical and not meant to be taken seriously. Well, neither is this JE :7

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  • The halting problem states that there is no general algorithm that can determine whether any arbitrary algorithm will halt. However it is quite feasible to derive tailored algorithms which can solve the halting problem for particular subsets of algorithms. The point (and proof) of the halting problem is that it is possible to construct a specific algorithm which introduces a paradox and thus nullifies the hypothesis.

    So it is possible that Deep Thought could have determined the (approximate) running time for

    • So it is possible that Deep Thought could have determined the (approximate) running time for the search for the answer.

      I knew my reasoning wasn't exactly correct because I had already posted this to another site and gotten replies similar to yours. Which is why I added a remark about my JE being satirical (it's mostly meant as a satire of the kind of people that try to prove "scientifically" that Superman, Spiderman or any other superhero can exist).

  • http://slashdot.org/~tomhudson/journal/134518 [slashdot.org]

    Kind of obvious in retrospect. The biggest argument people have with it is "it won't work because you can't go back in time even one second" to which I reply "your turing machine posits a LOT of impossibilities, whereas time travel is theoretically possible, at least for some particles under some conditions."

    Then I ask them to point out why it wouldn't determine, in 2 seconds of runtime, whether a problem halts or not. They can't - just more arm-waving.

  • the book is satirical and meant to be taken very seriously indeed.
  • Now that's a computer I could fall in love with...
  • If DT works anything like the consultant I was stuck with (emphasis on the con), it:
    1. figured how much it wanted to get paid,
    2. gave that estimate (N),
    3. sat on its ass for N - 1,
    4. produced the result it took 10 minutes to accomplish.

      Oh, yeah, and ...

    5. Profit!

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It's a naive, domestic operating system without any breeding, but I think you'll be amused by its presumption.

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