The Last Question

July 18, 2011

Many people think “The Last Question” was Isasc Asimov’s greatest short story, and I would probably agree. That is, I would agree if I thought had read enough of Asimov’s work to feel comfortable evaluating it as a whole. However, I have not actually read that much Asimov, particularly not that much of his short fiction. The reason is that a lot of what I have read seemed quite dated. There are often some really innovative ideas, but his notions about what would be possible in the far future sometimes seem hopelessly skewed.

For example, the whole of the Foundation series—amazing as some of its episodes are, even if they do involve people who regress to using coal-powered faster-than-light starships—is undone by an understanding of chaotic systems. That was not something Asimov could have known when he started writing. “The Encyclopedists” was published in 1942, while Edward Lorenz‘s meteorological work leading to the discovery of strange attractors and the “butterfly effect” wasn’t done until around 1960. (Lorenz, by the way, was one of the nicest scientists I have ever met, and always seemed interested in talking to students, even lowly undergraduates like me who were just working in the Green Building for the summer.) I remember as a kid hearing about how Asimov stayed on top of real science so well, and he incorporated it into his writing. In fact, I’m sure I saw (but did not read) some true science books he wrote for children. When I actually read more of his novels staring as a teenager, I was disappointed, however. Clearly, the man tried to get reasonable science into his fiction, and I give him credit for that; but I almost wish he hadn’t made the attempt. It’s easier for me to accept a SF premise that’s obviously fantastical that one that is put forward as if it might really reflect how the universe works.

“The Last Question” is the story of man’s quest to reverse entropy—to stop the seemingly inexorable run-down of the universe, as usable energy degenerates into waste heat. It is framed as six episodes, each of which involves humans (who change from drunken computer programmers to the disembodied consciousnesses of whole planets) coming to grips with the problem of limited resources and ultimately posing the question of how to reverse entropy to an “analog computer” (!) or “AC.” The answer is always the same, and the most famous line from the story: “THERE IS AS YET INSUFFICIENT DATA FOR A MEANINGFUL ANSWER.” Eventually the universe reaches its heat death, but the AC continues on. With a universe’s data to process, it finally achieves understands how to reverse entropy, “[b]ut there was now no man to whom AC might give the answer of the last question. No matter. The answer—by demonstration—would take care of that, too…. And AC said, ‘LET THERE BE LIGHT!’ And there was light—”

I first was exposed to this story as a planetarium show when I was a kid. I was old enough to understand all of it, including the ending, which came as a complete shock; and yet, once you have seen or read it, the philosophical conclusion at the end seems almost inescapable and remarkably profound.

There are explicit parallels running through the entire sequence of episodes. The computer changes, becoming more impressive with each iteration and name change. The size, locations, and communicative capacities of the AC are regularly mentioned. This gives the story a sort of concreteness that might otherwise be lost, as the AC becomes something so different than the original Multivac made of circuits that it becomes hard to conceive of.

And humankind changes too, growing alongside the computers. On thing I usually forget about the story is what happens to Man at the end. Man does not die, even as the universe collapses around Him. At the end, he merges with His ultimate creation, AC. By this point, AC seems to be just as much a living consciousness as Man, and by their merger, together they become the immortal god.

I don’t know how much Asimov really understood about entropy. The realization that the power to reverse entropy makes one tantamount to God makes sense even at the level of classical thermodynamics. However, the conclusion makes even more sense in the context of statistical mechanics. The modern understanding, through the work that began with Boltzmann and was largely completed by Shannon is that entropy represents our lack of knowledge about a system. If all we measure are the macroscopic variables of pressure, temperature, energy, etc., there are many possible states that the microscopic components that make up a system can assume. Entropy increases with temperature, because as the energy available to a system (such as, say, a gas) increases, the number of possible microscopic states increases exponentially. What this means is that, in order to decrease the universal entropy, an entity must know and be able to modify the specific conditions of every atomic component of the cosmos—“Ye shall be as gods.”

It’s a fascinating notion to me, as a physicist who is interested in the subtle natures of statistical and thermodynamic entropies. And at this point, I would also like to put in a plug for Boltzmann as one of the most original scientists of all time. Like Cantor—one of the most original mathematicians—his ideas were harshly criticized during his lifetime, driving him to depression. Yet not long after his death, his ideas had become utterly indispensable. Like Archimedes (if the stories are true), Boltzmann’s tomb is engraved with one simple mathematical fact, which manages to encompass all the man’s amazing work. While Boltzmann’s S = k log W is less famous than Newton’s F = ma or Einstein’s E = mc2, it really ranks with them as one of the fundaments of physical understanding.


12 Responses to “The Last Question”

  1. retrochef Says:

    As an engineer, while I don’t particularly like the almost philosophical approach to entropy I tend to see in physics, I do like “The Last Question.” There will eternally be a few elite thinkers who comprehend the ultimate futility of arguing with thermodynamics, but still can’t help but try to fight against it.

    • Buzz Says:

      The relationship between entropy and philosophy is actually rather unusual, at least from a historical perspective. Entropy was introduced to thermodynamics in the middle of the nineteenth century by Clausius, because it turned out to be a useful mathematical quantity. It was something one could construct out of pressure, volume, temperature, etc., which had the remarkable property that it would never decrease for a closed system. But it wasn’t assigned any physical meaning; it was considered to be a pure but useful abstraction. So far as I know, there were never any philosophical questions about it at this early stage.

      A few decades later, Boltzmann was studying the problem of the motions of the many atoms making up a gas. (Although, at that time, the physical reality of atoms was not by any means established; more on this later.) He came across a quantity, related to the amount of disorder in the system, which had exactly the same properties as the entropy. He multiplied it by a certain number (Boltzmann’s constant) to make the units match, and declared that it was the entropy.

      Today, we are popularly inclined to describe entropy as a measure of “disorder.” (That’s how it was described in a handout I got in fifth grade about all sorts of things related to energy. And in the Fiend Folio, one of the chaotic neutral Slaad lords was titled “Lord of Entropy.”) While the notion that the amount of usable energy (“exergy,” although physicists don’t use that term any more) is always decreasing as entropy increases goes back to Clausius and Kelvin, the idea that entropy is related to disorder was purely Boltzmann’s.

      However, despite the universal acceptance of this idea now, it was heavily criticized by scientists and philosophers in the late nineteenth century. The logical positivist philosophers attacked the ideas as unscientific, because the basis of Boltzmann’s statistical mechanics was in the atomic theory of matter. Since atoms were thought to be unobservable idealizations, the positivists thought that they were metaphysical and hence meaningless. (I will insert an aside here that many philosophers of science who have little training in actual science are notoriously bad at judging which theories are really scientific. Carnap, Popper, and Kuhn all made the blunder of dismissing real scientific ideas as unscientific, because they themselves couldn’t see how to test them effectively.) Eventually, Einstein showed that the atomic theory had numerous observable consequences on everyday scales. (His doctoral dissertation was the method that freshmen at my high school used to measure the size of molecules: Spread a known volume of liquid on the surface of another liquid with which it will not mix. If the layer is one molecule thick—as it is if the right substances are chosen—the size of the atoms is the volume of the drop divided by the area of the layer it spreads out to become.) After several experiments in the early twentieth century, atoms were accepted as definitively real, contrary to what the philosophers had thought.

      The relationship between the thermodynamic quantity that Clausius identified as useful and the statistical quantity that Boltzmann derived is sometimes rather subtle, and perhaps there are genuine philosophical questions in some unusual cases. However, the fact that the two are really the same is, in essentially every situation that might actually be encountered, beyond question. I had the good fortune in college to have two physics professors who were really interested in ensuring their students had a clear understanding of statistical entropy. There are many apparent paradoxes associated with the statistical definition of entropy, but they can all be resolved by looking very carefully at the mathematics underlying the definition of statistical entropy. Many of these problems were already solved by Boltzmann himself, but the unremitting hostility he faced from close-minded philosophers eventually drove him to take his own life.

  2. As a laybear, I also don’t like the quasi-metaphysical/philosophical approach to entropy I sense among physicists.

    As for ‘The Last Question,’ I don’t know what to say except that I like your observations on its depiction of the evolution of humanity (and its merger with AC), and that I’ve never read a speculative fiction story half as good.

  3. Diapadion Says:

    Its a good story. I’m not sure I would call it Asimov’s best piece of short fiction, though. It feels almost like a children’s story in many respects. Alternatively, one could argue that the structure and language are almost biblical in form (which really would be quite brilliant).

    Anyway, it does have this grand philosophical angle which made me go “woah” at first reading, but I agree with your other readers in that I can’t see as much more than a one time woah because it fails to address much relevant to humanity.

    If I had to pick my favorite Asimov short story, it would probably be something from I, Robot (and it happens I think the tales from that period are the best of the Robot stories, and I think the Robot stories outstrip those of the Foundation). Or, The Feeling of Power might be my favorite story.

    Also, the way this wp theme handles text and background contrast is almost criminally negligent.

    • Buzz Says:

      I’m rather fond of “The Feeling of Power,” although I don’t think it’s got the same innovation as “The Last Question.” My first exposure of “The Feeling of Power” was in my sixth-grade reading class. There were a few science fiction stories in the textbook every year, and in fifth and sixth grade, there were workbook pages about the genre and its conventions. In fifth grade, that included reviewing the three SF stories we’d covered that year, and I remember realizing that all three stories were very soft and fluffy; in particular, they all had friendly telepathic aliens. In sixth grade, by contrast, the tone was much darker, and the SF stories in the book included “The Feeling of Power” and the even more famous “To Serve Man.” The other stories were almost as dark.

      The very end of “The Feeling of Power” is very powerful, but the story suffers somewhat from Asimov’s dated notions about what computers would be capable of doing. He tended to have this problem a lot, as well as believing that civilizations would be able to use and maintain complicated technologies even with no idea how they worked. Neither of these mistakes was uncommon or, but they do make the premise of the story rather ridiculous, unfortunately.

      • Diapadion Says:

        “The very end of “The Feeling of Power” is very powerful, but the story suffers somewhat from Asimov’s dated notions about what computers would be capable of doing.”

        Funny, those are just about the exact words I would use to describe “The Last Question.”

        • Buzz Says:

          I think that the difference for me is that “The Feeling of Power” seems to be attempting for a realism that “The Last Question” lacks. The logical conclusion of “The Last Question” (that to able to reverse entropy on a universal scale makes you God) is correct, but I saw that the mechanism for achieving was clearly nonsensical, even at age eight. How exactly is AC supposed to survive the heat death of the universe? More importantly, how is it operating? To be able to process data indefinitely requires an external source of exergy. So by continuing to function long after the universe has died, AC has already massively violated the Second Law and reversed the increase of entropy.

          I had to change the WordPress settings to allow more nested comments in order to post this. Yay!

          • ‘The Last Question’ doesn’t violate the second law (or whatever). Rather, Asimove has snuck in the premise that AC exists primarily (and, at the end, exclusively) in ‘hyperspace.’ All the story requires is that some other portion of reality exists beyond our universe.

            • Buzz Says:

              That handwave is certainly present in the story, but it doesn’t seem that effective to me. If there were stuff going on in this “other place,” so that it could absorb the entropy from our universe, by increasing its own, the Second Law would be saved. But that has two problems: 1) It seems to contradict the fact that all AC could do in “hyperspace” was to think; there wasn’t other stuff for it to interact with. 2) That scenario also implies that you’re just moving on to another low-entropy region, like Adell and Lupov originally discussed; so the real problem isn’t solved in the end.

  4. Buzz Says:

    I just realized it would be really cool (or “nerd cool”) to have a shirt that says “S = k log W” on the front and “THERE IS INSUFFICIENT DATA FOR A MEANINGFUL ANSWER” on the back.

  5. […] to the AC computer series from Asimov’s “The Last Question” (which I have previously discussed). The computers in both stories were seemingly godlike, although with practically opposite […]

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