Summary: This is the fifth and final part of a series of presentations given at a public forum sponsored by the NASA exobiology branch. The forum, held in Palo Alto, CA, on Tuesday, August 26, 2003, was entitled, "The Drake Equation Revisited." This installment addresses the evolution of machine intelligence and the potential for civilizations that span the galaxy.
The Drake equation was developed as a means of predicting the likelihood of detecting other intelligent civilizations in our galaxy. At the forum, Frank Drake, who formulated the equation 42 years ago, moderated a debate between Peter Wardand David Grinspoon.
In this installment, the three participants respond to audience questions about the evolution of machine intelligence and the potential for civilizations that span the galaxy.
Previous parts of this series presented the opening remarks by Drake, Ward and Grinspoon and the first half of the question-and-answer period. See parts 1* 2* 3* 4* 5
Q: This discussion is all very biologically oriented, and we are now in an era of the digital developments. If you read Kurzweil, evolution is going to take us into a digital implementation in the not-too-distant future. And with evolution being an exponential factor, that bodes well for the existence of intelligence. Not necessarily biologic intelligence, but intelligence.
Grinspoon: Arthur C. Clarke, who as you know is the H.G. Wellsof the paleocybernetic age, once said that we are near the end of biological evolution and near the beginning of the evolution of intelligence. And I think that we have perhaps an innate bias against this idea. We don't like it. That the machines we create might outlive us and outlast us and become something superior to what we are.
But when we get over that emotional reaction, there's no logical reason to believe that machine intelligence won't, in fact, inherit the Earth, and perhaps inherit the Universe. And you can certainly imagine, even if it doesn't happen here, that on some planet intelligent machines have been created which are effectively immortal. In fact, I think that it's hard to argue the opposite. And so I very much agree with you that when we consider the entire spectrum of possibilities with evolution of extraterrestrial intelligence, that we do have to consider the existence of quasi-immortal machine civilizations out there.
And one intriguing possibility is that when we do receive a signal, which surely we will sooner or later - I prefer sooner - that we may not know if it comes from a machine or from a biological entity.
Q: One problem with humans reaching other star systems is that we don't come with off switches. If humans were replaced or supplemented with artificial intelligences that did come with off switches, or if this had happened on some other planet or some other star system, it seems likely that they would have explored other star systems and colonized them, including ours. Which means that if this sort of thing was common, it would be unlikely that it hasn't happened yet. But, apparently it hasn't happened yet.
Ward: Is your name Fermi?
Q: Yes, it is the Fermi paradox, but that Fermi paradox only works if you either have spacecraft that can go fast enough that the existing forms of life can take advantage of them, or if you have forms of life that can be turned off so that they can colonize the galaxy with spacecraft of modest speed.
Grinspoon: A couple of thoughts. One, I do think that there's this temporal bias, in that we see it as impossible to travel between the stars because in a human lifetime we can't conceive of traveling between the stars, because they're very far away and we're limited certainly by the speed of light, and probably, practically, by much lower speeds. But, why should other beings evolved on other planets care about the timescale of a human lifetime? You can imagine an intelligent sequoia tree that might not have a problem with interstellar travel. So I think that we shouldn't be too temporally chauvinist, just because we have such pitifully short lives and the stars are so far away.
But the other comment that I would make is that we don't know that that hasn't happened. Our solar system is almost entirely unexplored. And while I completely support radio SETIand I think it's just obvious that we should continue and expand our efforts for radio SETI because it's cheap and it seems destined to succeed sooner or later, I also think that there are other ways to search.
And I think that, while here we verge into science fiction and into tabloid journalism and whatever, but there's no reason why we shouldn't, as we explore the solar system, be on the lookout for artifacts. The asteroid beltcould be riddled with alien garbage, and we wouldn't know about it yet. And, certainly, if there was a buried obelisk on the moon, we would not have discovered it yet. So, it's entirely possible that somebody has been through our region of space in the billions of years that our planetary system has been here.
Q: Dr. Drake, in your introductory remarks about the factor L, you talked about how human civilization has gone from radio transmission to cable in a hundred years, and so effectively we're quiet now. But you said that there could be a civilization out there that was noisy for a billion years. I assume you don't mean that they had the intelligence to develop radio transmission, but then it took them a billion years to develop cable. So, what did you have in mind?
Drake: We, of course, have not disappeared yet. The number of our high-powered television transmitters has remained about constant at the present time. It's just that, looking into the crystal ball, one sees that within 100 years or so, we will probably drop that means of delivering television and go entirely to satellites, fiber opticsand cable. And the prospect is that at least that sign of our existence will disappear.
Now the big question is: Will something else replace it? For example, we are again seriously considering constructing solar-power satellites. These are huge solar-energy collectors we put in orbit. They transmit the power they capture to Earth by microwave beams. A few years ago these were considered and determined not to be practical economically. Not technologically, but economically. Now that picture's changed, and the engineers are telling us: Yes, these systems would return more value than it would cost to put them in orbit.
Now, if that's the wave of the future, you may have hundreds of such things in space. Their transmitter power is about a billion watts; that's what they transmit to Earth. All antennas are imperfect, they reflect a little power into space, one percent, say, even a very fine antenna. Well one percent of a billion watts is 10 million watts, which is more than our present typical TV transmitter. So, if that's the wave of the future - and, of course that's an appealing way, because it's clean power, there's no pollution, you're not overheating the Earth, there're no bad things to that - if that's the wave of the future, civilization may stay visible for a very long time.
Of course, a billion years, who knows? When we throw out a billion-year figure, we're talking about David's immortal civilizations, civilizations that want to communicate, and they create beacons for the benefit of other civilizations. Now, that's very science-fiction stuff, but you can't rule it out. And it has been proposed many times, seriously, that there is a galactic network, so to speak, of intercommunicating civilizations that have been in communication for literally billions of years, and if we just knew where to look and on what frequency, we could join that network. So it's that which, of course, is totally speculative - no evidence whatsoever for it's existence - which says, well, you must consider that perhaps, some very small fraction of civilizations remains detectable for a very, very long time.
Grinspoon: It's worth just thinking about the timescales of evolution. Biological evolutiontook us something like (depending on when you believe life started) a few billion years to get here. And then contrast that to the timescale of technological evolutionand look how much the world has changed in just the last 100 years. And so when we try to imagine the technology even 100 years from now it's challenging. Try to imagine the technology a thousand years from now, or 10 thousand years.
When you start talking about civilizations that may have lasted a million, or a billion years, then you can call it science fiction, but perhaps the science fiction writers might be those among us who are best qualified to imagine those capabilities. It's very difficult, but it's hard to rule out many possibilities that seem far-fetched, when you don't consider the timescale of technological change and what that may lead to over these cosmological timescales.
Q: We're not officially trying to contact anything, it's only through our TV transmissions and what-not. But 20 years from now, if we do detect an Earth-like planetsomewhere, do you think there would be an effort to direct communications towards that, and if so would it be radio or optical? Any opinions on that?
Drake: At the present time we're not attempting to contact other civilizations. We do not transmit. And there are two good reasons for that. One is it's very expensive; it's better to spend our resources listening. And the other is the Earth's doing it for us for free. There are 2000 that receive our television, and about 1500 of them are just now seeing Super Bowl I and wondering how that's going to come out.
But there is a protocol in existence which says that should a message be detected, we will not reply until we have understood the message, understood enough about what that message meant to construct, if desirable, a meaningful reply. But just how that would be done has not been determined.