Because what else would make a periodic signal? It turned out to be a rotating neutron star. One criterion to apply to a potentially purposeful phenomenon is whether it’s minimal in achieving a purpose. But does that mean that it was built for the purpose? The ball rolls down the hill because of gravitational pull. Or the ball rolls down the hill because it’s satisfying the principle of least action. There are typically these two explanations for some action that seems purposeful: the mechanistic explanation and the teleological. Essentially all of our existing technology fails the test of being minimal in achieving its purpose. Most of what we build is steeped in technological history, and it’s incredibly non-minimal for achieving its purpose. Look at a CPU chip; there’s no way that that’s the minimal way to achieve what a CPU chip achieves. This question of how to identify purposefulness is a hard one. It’s an important question, because radio noise from the galaxy is very similar to CDMA transmissions from cell phones. Those transmissions use pseudo-noise sequences, which happen to have certain repeatability properties. But they come across as noise, and they’re set up as noise, so as not to interfere with other channels. The issue gets messier. If we were to observe a sequence of primes being generated from a pulsar, we’d ask what generated them. Would it mean that a whole civilization grew up and discovered primes and invented computers and radio transmitters and did this? Or is there just some physical process making primes? There’s a little cellular automaton that makes primes. You can see how it works if you take it apart. It has a little thing bouncing inside it, and out comes a sequence of primes. It didn’t need the whole history of civilization and biology and so on to get to that point. I don’t think there is abstract “purpose,” per se. I don’t think there’s abstract meaning. Does the universe have a purpose? Then you’re doing theology in some way. Th