Thoughts on Fermi’s Paradox

I’ve been reading Richard C. Meredith’s The Sky is Filled With Ships. (1969)

Richard C. Meredith's The sky is filled with ships
Pulp at its pulpiest

It’s not a great piece of art, but it does satisfy my pulp habit and makes for agreeable bus reading. The basic plot of the novel… (now, before I go on, as an aside, I should like to mention that I hate to be one to spoil a plot; however, I’m guessing few people will actively seek out this book, and, more than that, perhaps unsurprisingly, the title itself pretty much gives away the premise.) The basic plot of the novel is that dissent in the Terran Federation has caused a political schism, leading to both sides of the divide gearing up for a massive interstellar civil war. A novel questionably novel in 1969, and today undeniably clichéd.

Though the plot is not terribly thought provoking, what has me pensive are Meredith’s descriptions of the information probes used to communicate between the space armadas convening from legion distant planets. Given the amount of time it would take radio signals to reach ships around distant stars, he has chosen to instead load messages onto probes that are blasted into hyperspace toward friendly ships. As a (perhaps unintentional) consequence, this removes the content from the airwaves (or the vacuum-waves, I guess one might say, to be more precise). Space no longer has radio signals bouncing back and forth between intelligent entities — messages are quiet and more private.

And it’s that bit that brought me back to musing about an old problem facing xeno-sociologists. Enrico Fermi — yes, that Enrico Fermi — during a casual lunch with colleagues, did some quick calculations on the back of his napkin and figured that, if we assume that we’re a pretty average civilization on a pretty average planet, much like Tennyson does —

This truth within thy mind rehearse,
That in a boundless universe
Is boundless better, boundless worse.

Think you this mould of hopes and fears
Could find no statelier than his peers
In yonder hundred million spheres?

-Lord Tennyson, “The Two Voices,” (pub. 1844)

— then we should have been contacted by extra-terrestrial intelligences many times over by now. That conjecture has become known as the Fermi Paradox, and it has about as many possible resolutions as there are stale science-fiction plots in paperback. However, in looking through SETI’s sample page of signal anomalies, I was struck by the possible issue concerning the simulated detection of the Wow! signal. (The Wow! signal was a strong narrowband signal detected in 1977 bearing many of the hallmarks that we would expect a signal of intelligent origin to bear. More on Wikipedia.)

The major issue here is — that signal was a strong candidate signal, but it was also one that we have not detected since 1977. Ok, so… why is that relevant? Well, because, in many ways, it bears similarity to the signals that we on Earth have sent out into space. Consider the Arecibo message. Here was a message that took less than 3 minutes to send, was aimed at a particularly dense star cluster, and was sent only once. Assuming there are intelligent, technological societies in our near-interstellar neighborhood, why shouldn’t we expect them to do the same thing we have? That is: send whatever messages they do in very short bursts, and have them directed at a dense cluster of targets? Well, if that does end up being the case, we’re screwed. We’re not located in a dense star-cluster (so we may be less likely to have signals pointed at us) and we’ve traditionally been looking for repeating signals (which might be especially uncommon).

Of course, this is assuming intelligences similar to ours. For a slightly more advanced and mobile society, there’s another other possibility that stands unaddressed — if such better societies (as per Tennyson) are anything like our earth-bound society, then we might expect there to be some form of beacons, like lighthouses or bell-buoys, demarcating dangerous areas such as asteroid fields that might be difficult to spot under particular conditions. The idea is reasonable enough that when pulsars were first discovered, they were thought to be beacons of this type. One might raise the objection, of course, that with so many pulsars and stars, why have beacons at all? But to this objection, two counterarguments spring to mind. One — beacons of that sort can be useful over short distances where interpolation of location from stellar coordinates might provide a fair amount of error without very precise instrumentation on board the starships (which may turn out to be unreasonable given that we’re assuming a much more advanced society that doubtless would have such instrumentation). And two — such beacons could serve as homing signals, in that it is much easier to navigate towards a point than it is to use a form of dead reckoning (estimating location from initial heading plus approximate distance traveled) or from interpolation of distant landmarks (which, again, requires careful measurement and quite a bit of math). Under a system of homing beacons, dumb probes or interstellar couriers could shuttle between locations easily without need of a lot of computerized navigation.

The overall problem with the above, though — in all our searches so far, we have detected no such beacons. So, why is this? Well, it could be that if they exist, we are not picking up on them for a few reasons. Could be that their operation makes them look like pulsars, in which case we may never detect them as markers of intelligence. Or it could be that if they do exist, that they are broadcasting in some form of compressed signal which could be difficult to distinguish from noise. Or could be that the signal strength is not strong enough to pick up on Earth above the general noise of space. Or, perhaps most simply, they simply don’t exist.

For all SETI enthusiasts, it’s actually the last of those options that is the most striking, and, in some ways, the most depressing. We’ve been listening to the heavens for over a century now, and though we keep finding interesting natural phenomena, we’ve found nothing that clearly indicates that there’s another intelligence out there. Fermi, in asking “Where are they?” was wondering why we hadn’t been contacted time and time again. What he may have found more perplexing is that even with an open ear to the sky, we’re still just as in the dark as we were before we started listening. Now, I’m not alone in thinking that part of the problem might be that we just don’t broadcast much ourselves in the way of clear signals. Indeed, I’ve thought for a while the best thing that we could do for purposes of trying to establish communication with other cultures would be to stick a massive solar-powered radio tower on the back of the moon (to reduce the amount of bleed toward earth), and blast out, in all directions, a simple progression of numbers. As Sagan proposed in Contact, this could be a series of primes, or, as on Lost, it could as easily be an incrementing signal, or barring either of those, merely a complex repeating pattern. Anything simple, analog, and clear enough that it would stick out from the cosmic background like a sore thumb. Critics (like The Hawkman) suggest this could be dangerous, but SETI and I contest we may get nowhere if we don’t try. If we all just sit back and listen, it seems as if it is bound to be a lonely future. After all, if other societies are taking a “listen” strategy over a “shout” one, then it might just take us making the first move to get things rolling. If we’re all listening, but no one’s communicating, then it will be like sitting on a bus full of people with their earbuds in — forever.

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