Where Are They? Two Views
Why haven't we found intelligent life elsewhere in the universe? And what are the chances we will find such life? Ray Kurzweil and John Smart (via your erstwhile hosts) propose a couple of different ideas.
STEPHEN: In his new book, The Singularity is Near, Ray Kurzweil has some interesting thoughts on the Drake equation and the Fermi paradox. The values he would put into Drake's equation (and he defends these values) yield a total number of radio broadcasting civilizations of 1.25. He is arguing that we're probably alone in this galaxy.
If that's the case, the Fermi paradox is no paradox at all. We just have a lack of evidence for something that doesn't exist. Kurzweil believes it is the destiny of any civilization that reaches our level of development to spread rapidly (relative to the age of the galaxy) throughout the galaxy. If intelligent civilization were really a mundane, "everyday" development in our galaxy, one or more of these civilizations would have knocked on our door a long time ago. But it isn't, so they aren't.
PHIL: John Smart argues it differently. He estimates that there may be as many as 2200 planets on which technological civilization has evolved. But he says that the reason we never hear from them is that they get interested in the next substrate and move their civilization to it, moving in rather than out into the universe.
Ultimately, we can model this and infinite other universes mathematically. If we can model them in great enough detail, we can "create" them as virtual worlds. Maybe advanced civilizations find that they have many, many more worlds to explore by moving in than by moving out. So maybe one day we (or our descendants) will more or less abandon this universe as a macroscale construct. If we do, the era during which we existed as a radio-wave-producing species will be over. Maybe no one out there will ever catch our signature, just as we have (so far) missed out on the radio signatures of the other species which have made the leap to inner space. Thus Fermi's paradox is no paradox.
I'm not sure whether I'm completely convinced by this. It seems to me that, given sufficient technological development, we'll always have plenty of patience for this universe, seeing as we need it to "power" all of our other universes.
On the other hand, innerspace might be the quickest and most reliable way to explore. By exploring all the possible worlds (rather than just the ones we can find in this galaxy/universe) we can meet up not only with everyone else in the universe, but also with everyone who was never there to begin with.
STEPHEN: Interesting. Kurzweil spends some time in The Singularity is Near talking about the computational capability of matter - specifically your average two-pound rock. He explains that, through a process of reversible logic gates (which is beyond my understanding), two pounds of "dumb" matter does more calculation than our best supercomputers with very little energy having to be added for this "computer" to operate.
What does a rock calculate? Presently, itself. It's hard, not elastic. It reflects light at a certain wavelength, etc. But Kurzweil proposes that we will harness much of the calculating potential of the dead matter in our solar system and will move out into the galaxy doing the same.
Going both into cyberspace and out into outerspace.
PHIL: So they may be "out there" already, but we'll never find them via a SETI-style search. In fact, I'm not sure how we would find them. We can go into cyberspace and model them, but that isn't exactly the same thing. Somehow, we'll have to find a way to "hack into" their system. Or eventually come to terms with the fact that we are the only piece of software running on the universe's hardware.
BTW, don't worry about this:
...through a process of reversible logic gates (which is beyond my understanding), two pounds of "dumb" matter does more calculation than our best supercomputers...
I'm sure that between modeling itself and trying to understand the universe, your brain is doing a lot more computation than the rock!