Over at Open the Future, Jamais Cascio has compiled a list of 10 Must-Know Concepts for the 21st Century, partially in response to a similar list compiled by George Dvorsky. I'm flattered that Jamais includes "Carlson Curves" on his list, and I'll give one last "harrumph" over the name and then be silent on that point.
Jamais's list is good, and well worth perusing. George Dvorsky's list is interesting, too, and meandering through it got me restarted on a topic I have left fallow for a while, the probability of intelligent life in the universe. More on that in a bit.
I got headed down that road because I had to figure out what the phrase "cosmological eschatology" is supposed to mean. It doesn't return a great number of hits on Google, but high up in the list is an RSS feed from Dvorsky that points to one of his posts with the title "Our non-arbitrary universe". He defines cosmological eschatology through quoting James Gardner:
The ongoing process of biological and technological evolution is sufficiently robust and unbounded that, in the far distant future, a cosmologically extended biosphere could conceivably exert a global influence on the physical state of the cosmos.
That is, you take some standard eschatology and add to it a great deal of optimistic technical development, probably including The Singularity. The notion that sentient life could affect the physical course of the universe as a whole is both striking and optimistic. It requires the assumption that a technological species survives long enough to make it off the home planet permanently, or at least reach out into surrounding space to tinker with matter and information at very deep levels, all of which in turn requires both will and technical wherewithal that has yet to be demonstrated by any species, so far as we know. And it is by no means obvious that humans, or our descendants, will be around long enough to see such wonders in any case; we don't know how long to expect the human species to last. From the fossil record, the mean species lifetime of terrestrial primates appears to be about 2.5 million years (Tavare, et al, Nature, 2002). This is somewhat less than the expected age of the universe. Even if humans live up to the hype of The Singularity, and in 50 years we all wind up with heavy biological modifications and/or downloaded consciences that provide an escape from the actuarial tables, there is no reason to think any vestige of us or our technological progeny will be around to cause any eschatological effects on the cosmos.
Unless, of course, you think the properties of the universe are tuned to allow for intelligent life, possibly even specifically for human life. Perhaps the universe is here for us to grow up in and, eventually, modify. This "non-arbitrary universe" is another important thread in the notion of cosmological eschatology. Dvorsky quotes Freeman Dyson to suggest that there is more to human existence than simple chance:
The more I examine the universe and study the details of its architecture, the more evidence I find that the universe in some sense must have known that we were coming. There are some striking examples in the laws of nuclear physics of numerical accidents that seem to conspire to make the universe habitable.
I read this with some surprise, I have to admit. I don't know exactly what Dyson meant by, "The universe in some sense must have known we were coming." I'm tempted to think that the eminent professor was "in some sense" speaking metaphorically, with a literary sweep of quill rather than a literal sweep of chalk.
Reading the quotation makes me think back to a conversation I had with Dyson while strolling through Pasadena one evening a few years ago. My car refused to start after dinner, which left us walking a couple of miles back to the Caltech campus. While we navigated the streets by starlight, we explored ideas on the way. Our conversation that evening meandered through a wide range of topics, and at that point we had got onto the likelihood that the Search for Extraterrestrial Intelligence (SETI) would turn up anything. Somewhere between sushi in Oldtown and the Albert Einstein room at the faculty club, Dyson said something that stopped me in my tracks
Which brings me, in a somewhat roundabout way, to my original interest: where else might life arise to be around for any cosmological eschatology? It seems to me that, physics being what it is, and biochemistry being what it is, life should be fairly common in the universe. Alas, the data thus far does not support that conclusion. The standard line in physics is that at large length scales the universe is the same everywhere, and that the same physics is in operation here on Earth as everywhere else, which goes by the name of the Cosmological Principle. More specifically, the notion that we shouldn't treat our little corner of the universe as special is known as the Copernican Principle.
So, why does it seem that life is so rare, possibly even unitary? In Enrico Fermi's words, "Where is everybody?"
At the heart of this discussion is the deep problem of how to decide between speculative theory and measurements that are not yet demonstrably – or even claimed to be – complete and thorough. Rough calculations, based in part on seemingly straightforward assumptions, suggest our galaxy should be teeming with life and that technological cultures should be relatively common. But, so far, this is not our experience. Searches for radio signals from deep space have come up empty.
One possibility for our apparent solitude is that spacefaring species, or at least electromagnetically noisy ones, may exist for only short periods of time, or at such a low density they don’t often overlap. Perhaps we happen to be the only such species present in the neighborhood right now. This argument is based on the notion that for events that occur with a low but constant probability, the cumulative odds for those events over time make them a virtual certainty. That is, if there is a low probability in any given window of time for a spacefaring race to emerge, then eventually it will happen. Another way to look at this is that the probability for such events not to happen may be near one, but that over time these probabilities multiply and the product of many such probabilities falls exponentially, which means that the probability of non-occurrence eventually approaches zero.
Even if you disagree with this argument and its assumptions, there is a simple way out, which Dyson introduced me to in just a couple of words. “We could be first,” he said.
“But we can’t be first,” I responded immediately, without thinking.
“Why not?” asked Dyson. It was this seemingly innocuous question, based on a very reasonable interpretation of the theory, data, and state of our measurement capability, that I had not yet encountered and that provided me such important insight. My revelation that evening had much to do with the surprise that I had been lured into an obvious fallacy about the relationship between what little we can measure well and the conclusions we make based on the resulting data.
Despite looking at a great many star systems using both radio and laser receivers, the results from SETI are negative thus far. The question, “Where is everyone?”, is at the heart of the apparent conflict between estimates of the probability of life in the galaxy and our failure to find any evidence of it. Often now called the Fermi Paradox, a more complete statement is:
The size and age of the universe suggest that many technologically advanced extraterrestrial civilizations ought to exist. However, this belief seems logically inconsistent with the lack of observational evidence to support it. Either the initial assumption is incorrect and technologically advanced intelligent life is much rarer than believed, current observations are incomplete and human beings have not detected other civilizations yet, or search methodologies are flawed and incorrect indicators are being sought.
A corollary of the Fermi Paradox is the Fermi Principal, which states that because we have not yet demonstrably met anyone else, given the apparent overwhelming odds that other intelligent life exists, we must therefore be alone. Quick calculations show that even with slow transportation, say .1 to .8 times the speed of light, a civilization could spread throughout the galaxy in a few hundred million years, a relatively short time scale compared to the age of even our own sun. Thus even the presence of one other spacefaring species out there should have resulted in some sort of signal or artifact being detected by humans. We should expect to overhear a radio transmission, catch sight of an object orbiting a planet or star, or be visited by an exploratory probe.
But while it may be true that even relatively slow interstellar travel could support a diaspora from any given civilization, resulting in outposts derived from an original species, culture, and ecosystem, I find doubtful the notion that this expansion is equivalent to a functioning society, let alone an empire. Additional technology is required to make a civilization, and an economy, work.
Empires require effective and timely means of communication. Even at the substantially sub-galactic length scales of Earthly empires, governments have always sought, and paid for, the fastest means of finding out what is happening at their far reaches and then sending instructions back the other way to enforce their will; Incan trail runners, fast sailing ships, dispatch riders, the telegraph, radio, and satellites were all sponsored by rulers of the day. Without the ability to take the temperature of far flung settlements – to measure their health and fealty, and most importantly to collect taxes – travel and communication at even light speed could not support the flow of information and influence over characteristic distances between solar systems. Unless individuals are exceptionally long-lived, many generations could pass between a query from the one government to the next, a reply, and any physical response. This is a common theme in science fiction; lose touch with your colonies, and they are likely to go their own way.
So if there are advanced civilizations, where are they? My own version of this particular small corner of the debate is, “Why would they bother to visit? We’re boring.” A species with the ability to travel, and equally important to communicate, between the stars probably has access to vastly more resources than are present here on Earth. Those species participating in any far-reaching civilization would require faster-than-light technology to maintain ties between distant stars. Present theories of faster than light travel require so-called exotic matter, or negative energy. Not anti-matter, which exists all around us in small quantities and can be produced in the lab, but matter that has properties that can only be understood mathematically. For humans, exotic matter is presently neither in the realm of experiment nor of experiment’s inevitable descendant, technology.
With all of the above deduction, based on exceptionally little data, we could conclude that we are alone, that we are effectively alone because there isn’t anyone else close enough to talk to, or that galactic civilizations use vastly more sophisticated technology than we have yet developed or imagined. Or, we could just be first. Even though the probabilities suggest we shouldn't be first, it still may be true.
But as you might guess, given our present technological capabilities, I tend toward an alternative conclusion; we could acknowledge our measurements are still very poor, our theory is not yet sufficiently descriptive of the universe, and neither support much in the way of speculation about life elsewhere.
Now I've gone on much too long. There will be more of this in my book, eventually.