I happen to think that the heuristic is a very clear sign of one of the biggest shortcomings of present-day science and technology. You see, what it's saying is that there is some kind of secret ingredient that nature is adding to make stuff complex -- and that we don't know from a scientific point of view. Well, actually, for the past fifteen years I've been working to try to find that ingredient; in a sense, my new book, A New Kind of Science, is about what that ingredient is.

The whole thing is a long story -- that's why it takes a whole book to explain it -- but the essence of it is that it's our reliance on mathematical equations and traditional mathematics that have made us miss what's going on. If, instead of using mathematical questions, one thinks about things in terms of simple computer programs, then one can quite quickly see what's going on. And I guess that the big discovery I made in the early 1980s is that there are some very simple computer programs that can do very complex things -- things that are just like the things we see in nature.

Now here's the good bit: it turns out that those simple computer programs can often behave like universal computers. And what that means is that they can do stuff that's as complicated as anything, including anything our fancy electronic computers do. There's a major new piece of intuition here. You see, people have tended to assume that to make a universal computer -- a general-purpose machine -- the thing had to be constructed in a pretty complicated way. Nobody expected to find a naturally occurring universal computer lying around. Well, that's the thing I've found that isn't true. There are very simple universal computers. In fact, I think that lots of systems we find all over the place in nature can act as universal computers.

Stork: So, what does this mean?

Wolfram: Well, we can think of the behavior of any system in nature as being like a computation: the system starts off in some state -- that's the input -- then does its thing for a while, then ends up in some final state, which corresponds to the output. When a fluid flows around an obstacle, let's say, it's effectively doing a computation about what its flow pattern should be. Well, how complicated is that computation? It certainly takes quite a lot of effort for us to reproduce the behavior by doing standard scientific computing kinds of things. But the big point I've discovered is that this isn't surprising; the natural system itself is, in effect, doing universal computation, which can be as complicated as anything.

So, in other words, all our big fancy computers -- and our brains for that matter -- really aren't capable of computations that are any more sophisticated than a piece of fluid. It's a humbling conclusion -- sort of the ultimate put-down -- after we discover the earth isn't the center of the universe, that our bodies work mechanically, and so on. But it's very important in thinking about extraterrestrial intelligence.

Here's why. If we receive a signal, we've got to figure out whether it came from something intelligent or not. Now here's where the issue about natural versus artificial gets very confusing. If the thing we see is too simple, we're probably going to conclude it's not coming from anything intelligent. Actually, if we'd only seen the monolith, and it hadn't been quite as big as it was, we might have concluded that it was just a crystal -- some very fine specimen of a black gemstone.

Likewise, when Dave enters the stargate, we first see just a plain row of lights, which could easily come from some simple physical process. Later, things start looking more complicated. And then, at times, things look sufficiently random and complicated that we would probably conclude that they were just natural, and not artificial or intelligently created in any way.

So actually the stargate sequence is a very good example of how difficult it can be to tell whether something is natural or artificial, whether it has been made intentionally or just grew naturally. I'm not even sure what Kubrick had in mind in parts of that sequence. Later on in the sequence, weseem to be over a natural planet surface, but Kubrick added some flash- ing octahedra just to make it clear that the whole thing wasn't supposed to be completely natural -- unless perhaps those octahedra were crystals, or something.