The Benfords — Jim at Microwave Sciences, Gregory at the University of California’s Irvine campus, and Dominic (Jim’s son) at NASA GSFC — believe that advanced societies, if they are to be found, ought most likely to exist toward the galactic center, and probably at distances of over a thousand light years. We’re thus talking, in all likelihood, about interstellar beacons rather than targeted transmissions when it comes to SETI. And if beacons are indeed at play, what can we say about their costs, and do our own standards of terrestrial cost have any application in an ETI context?
The message here is that any SETI search has to make assumptions about the beacon builders, and if we can determine something about the economics of the situation, we may learn how to target our searches more effectively. Here’s the essence of the argument about ETI:
We assume that if they are social beings interested in a SETI conversation or passing on their heritage, they will know about tradeoffs between social goods, and thus, in whatever guise it takes, cost. But what if we suppose, for example, that aliens have very low cost labor, i. e., slaves? With a finite number of slaves, you can use them to do a finite number of tasks. And so you pick and choose by assigning value to the tasks, balancing the equivalent value of the labor used to prosecute those tasks. So choices are still made on the basis of available labor. The only case where labor has no value is where labor has no limit. That might be if aliens may live forever or have limitless armies of self-replicating automata, but such labor costs something, because resources, materials and energy, are not free.
Our point is that all SETI search strategies must assume something about the beacon builder, and that cost may drive some alien attempts at interstellar communication.
SETI always seems to come with a built-in willingness to think the best of extraterrestrial cultures. If an alien civilization is sending out a message, it must be doing so out of altruism. The Benfords, though, are interested in exploring motivations from a different angle. They’d like to relate them to the only case of a technological civilization we know of, ourselves, and speculate based on human history. From that perspective, there are two reasons for sending out messages across vast time scales.
Think about what people do. You can go to the Tower of London and explore the chambers where famous prisoners like Thomas More were kept. Invariably, on the walls, you’ll find graffiti, names written into the stone. People have an apparently robust need to engage in one-way communication, putting a note in a bottle and throwing it. Indeed, the Pioneer and Voyager spacecraft are examples of the impulse. Is it likely that any of these tiny vessels will ever be intercepted? Yet putting our names, our stories, our music and our pictures on board outgoing vehicles is a method that resonates. We have a need to encapsulate who we are.
A second reason is the drive to communicate the optimum things about our culture, what Matthew Arnold called “…the best that has been thought and said in the world.” Here the Benfords cite time capsules and monuments as examples of our need to propagate our culture. The contemplation of a legacy is involved here, especially in a scenario where human lifetimes are rising. Here again the communication can be one-way. The statue of King Alfred my wife and I admired in Winchester some years back was not built to impress people within a tight time frame, but to stand as a monument that would reach future generations.
So imagine scenarios like this: A civilization with an ability to plan over millennial time scales foresees problems that are beyond its capabilities. A SETI beacon might encapsulate a call for information and help — send us everything you have on stellar warming…
Here’s another: A civilization in its death throes decides to send out an announcement of its existence. We were here and are no longer, but as long as this message endures, so in a sense do we. And let’s not discount sheer pride of the sort that could keep a beacon in operation long after the beings that built it were gone. Robotically maintained, it might boast of achievements set against the backdrop of the ruin that may eventually attend all technological cultures. Or perhaps we’ll run into interstellar proselytes, out to convert the galaxy to a particular set of beliefs by placing their highest values into their outgoing signal.
I’m glad that finally somebody in mainstream SETI studies have proposed something different to think about when it comes to listening to, or broadcasting signals.
While I feel SETI should do more than just do the radio thing and look for possible Bracewell Probe signals, the Benford Clan at least looked outside the box.
The Monument Beacon theory sounds good, but something else should be added onto that.
If a suspected source is found, perhaps we should train all of our available listening, optical, and any other measuring devices we can muster to locate a Transcension Fossil in its general direction.
Yeah I know, semi-religious technorapture crap and such an object would be hard to find, even if the broadcast signal was strong enough.
But if we were lucky enough to intercept a Beacon in the first place, why not trace it back to the source to see if such things as Technological Singularities take place?
It could explain the Fermi Paradox.
And give us a clue to our ultimate fate possibly.