This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Let’s start by clearing something up. Whatever the ins and outs of the search for extraterrestrial intelligence over the years (that I’ll label as SETI) the bottom line is that we have not yet done enough to tell whether the cosmos is devoid of communicative species or crammed with them. Nowhere has this been articulated better than in the work by Jason Wright, Shubham Kanodia, and Emily Lubar of Penn State and their ‘Haystack equation’. This shows, unequivocally, that to date we’ve searched about as much as if we’d stared into a modest hot-tub’s worth of water from all of Earth’s oceans.
Consequently, to say that ‘there’s clearly nothing out there’ is like looking in that hot tub, not finding a dolphin, and concluding that dolphins therefore do not exist anywhere on the planet.
Given that fact, I think it’s perfectly reasonable to examine how communications across interstellar space might play out, should they exist. This does, of course, require a whole bunch of prior assumptions.
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We have to assume that really long-distance communications, whether by radio, laser, beams of neutrinos, massive engineering of weird stellar transit signals, or other barely imagined options are actually possible at all. We have to assume, or at least posit, that information might flow across interstellar space either as inadvertent side effects of a busy species (noisily broadcasting or carelessly pointing lasers, among other things) or as deliberate signals – seeking replies, establishing communications, or tracking a species’ own kind.
We would also have to assume that technologically inclined species can arise and survive for long enough to expend time and energy on any of these things. That’s part of the depressing, although potentially realistic, Anthropocene mindset. But equally, simply shrugging our shoulders and saying that it’s all hopeless shuts down a discussion that could be very important.
That importance could stem from the relevance of information itself. At all levels, information appears to be not just an integral part of the phenomenon of life on Earth, but the flow of information may represent a critical piece of what makes something alive versus not alive (that flow and informational influence might even be what life is).
One small facet of this is very evident in how social animals deploy the flow of information. Imagine, for example, that humans didn’t communicate with each other in any way. It’s next to impossible to imagine that, right? We’re communicating even when we’re not speaking or touching. If I merely watch you walk down the street I’m accumulating information, adding that to my internal stash, analyzing, and incorporating it into my model of the world.
There’s a much bigger discussion to be had there, but to come back to SETI. It seems that there is a built-in inevitability for life to cause and participate in information flow, and we should assume that extends across interstellar distances too. We ourselves have taken baby steps towards this – from our transmissions to our SETI efforts, to the fact that we maintain communications with our most distant robotic spacecraft, the Voyagers.
As we’ve seen with studying the ideas of the so-called Fermi Paradox, in principle it’s pretty ‘easy’ for interstellar explorers to spread across the galaxy given a few million years. It therefore should be even easier for an information-bearing network to spread across the galaxy too. Signals can move at up to the speed of light, so the bottlenecks come from issues like the fading of signal strength with distance, the timescale of development of the infrastructure to receive and transmit, and the choices made on directionality (perhaps).
The beautiful thing is that we can model hypotheses for this galactic information flow – even if we don’t know all the possible ifs, buts, and maybes. We can, in principle, test hypotheticals about the structure of information-bearing interstellar networks, which will also relate to the known physical distribution and dynamics of star systems and planets in our galaxy.
Perhaps somewhere in there are clues about where we stand in relation to conversations that could be skittering by us all the time. Perhaps too are clues about what those conversations would entail, what the most valuable interstellar informational currencies really are.
Watch, or listen to, this space.