what a crab computer can tell us about seti

A study using soldier crabs to emulate computers is actually a perfect illustration of how different alien computing could be.
giant crab

One of the most bizarre things about computers is that the notion of computing is a mathematical construct in its purest form. This sort of thing drives philosopher John Searle up a wall mostly because it makes trying to define the boundaries of what intelligence and cognition are in living and nonliving things exceedingly difficult, but the fact is that as long as you can encode something as 0s and 1s, and create logic gates which are then used in the basic logical operations that work with data, you’ve got the basics of a computer.

And that’s how a trio of researchers built a computer using soldier crabs. Yes, you read that right, actual moving, hard shelled crabs that usually live in the tropics and like to swarm together. By having them move in a specially designed maze, the researchers created rudimentary OR and AND gates which form the basis of CPUs. Great, so if by some odd fluke 2012 does destroy civilization, we can still surf the web and check our e-mail. We’ll just need soldier crabs. Lots and lots and lots of solider crabs. I’m thinking about 150 quadrillion ought to do it…

But here’s the serious question. if computing is basically substrate independent, doesn’t it mean that calling human brains computers and likening our personalities to emergent properties of what is basically software, as so many Kurzwelian transhumanists do, is not all that far from the mark? After all, the brain takes in data and performs computations with it to make a decision about what to do next, right? And there are quite a few asynchronous processes going on in the background as well, moving data around to make sure we have some awareness of our environment while going about our daily tasks.

We could even liken the movement of signals within the brain to currents flowing through logic gates. How is our brain not like a computer, just in a squishy organic form? Well, going by this this premise we could concede that the brain is a computer, but we would then also have to accept that anything that can interact with its environment and store information must be a computer too. After a certain limit, the definition of a computer would become so broad as to encompass a great deal of the universe and turn into something functionally meaningless for all intents and purposes.

So what would be a better way to define the solider crab computer then? Well, we could say that researchers used soldier crabs to perform some very basic computations and show that in a computer, all that will matter is the ability to encode and decode data. How this data is moved around or what encodes it is up to the actual designer and can differ widely, something already well known in computer science. The only reason why this experiment got some media attention is because it sounds like the kind of odd, whacky science that a pop sci news source loves to cover for its novelty factor.

And if the press really wanted to make things interesting, they would’ve looked past the oddball premise and noted that this is one of the reasons why it would be difficult to try and communicate with alien civilizations via active SETI because their computers are highly unlikely to be anything like ours and for all we know, they may well herd bacteria or special molecules through a logic gate encoding base-3 data. To them, our 1s and 0s would be little more than garbage data collected from random phenomena in deep space, and summarily discarded. All of our attempts to distinguish ourselves in a binary format would be for naught, just as their attempts to send back something in base-n would also be lost to our automated systems, interpreted as white, garbled noise passing through space, if it’s interpreted at all.

Maybe that’s another possible solution to the Fermi Paradox? Could it be that intelligent aliens are abundant through the galaxy if not the universe and even live close enough to each other to try communication (though I think it’s rather unlikely based on evolutionary theory’s implications for astrobiology), but wouldn’t you know it, they simply can’t understand each other. Even the story of the mythical Tower of Babel just wouldn’t cover how profound the miscommunication is because even after being punished for attempting to literally touch the sky through sheer ingenuity and cutting-edge engineering, the workers could at least understand that their fellow builders were trying to say something.

If they were alien species on different worlds, they wouldn’t even realize that someone was talking to them. Or even talking for that matter. This means that active SETI is unlikely to be successful, especially if it follows the advice of those who say that we need to restrict communication to binary signals only, and that we must be mindful that a burst of data into outer space is akin to walking into a cave in the middle of a vast desert and whistling a few notes. Maybe someone or something will hear it, but don’t get all that hopeful about some creature whistling back because that creature might not even have ears…

See: Gunji, Y., et al. (2012). Robust soldier crab ball gate Complex Systems 20 (2011) 2 arXiv: 1204.1749v1

# astrobiology // active seti / alien civilizations / computer science

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