Are We Alone?

1/13/03

In my series of essays, this is probably one of my favorites. I have written this in the past and misplaced it, so I enjoy writing it again with a few years of additional thought being put into it.

Everyone who has known me well, knows that I've been a geek from an early age. Many may not know that my original interest in science started with astronomy. It has been a passion of mine since about 6 or 7 years old. I used to look at books on astronomy, read about the planets. I was in heaven. I still visit the Hubble Space Telescope web site on a regular basis. I can't stop looking at all those amazing photograhs of space.

My fascination in astronomy carried over to science fiction. Science fiction novels were among the first novels I ever read for pleasure, and I read a number of them. Particular favorites were Isaac Asimov, Piers Anthony, and Robert Heinlen. I've read almost everything Heinlen has ever written and I've read a good number of Asimov's over 300 book.

People who have seen my computers may have noticed I run the SETI@Home screen saver on almost every computer I've used. For those of you that don't know, the SETI@Home screensaver is a project run out of the Berkeley SETI (Search for Extraterrestrial Intelligence) program. They collect data from the Arecibo radio telescope in Puerto Rico. These screensavers then analyze the data, searching for intelligent signals. Currently, over 4 million people have volunteered a collective 1.2 million years (and counting) of data processing time. That makes SETI@Home the single largest distributed computing program ever.

But, back to the topic at hand. Are we alone? Surely I would think not, since I've devoted so much time to crunching data for SETI@Home, right? Well, that's not entirely the case. I feel and have felt for some time, that the SETI program will fail to find any signs of intelligent life. In what follows, I'll try to lay out the rationale for why I believe that. Keep in mind, for a good portion of my life, I felt the exact opposite. I felt that the universe, and indeed our own galaxy, the Milky Way, was teeming with intelligent life. After a great deal of research and thought, I've had to face the unhappy truth that we will likely never encounter intelligent aliens in person, ever, and we may never hear from them either.

There is a famous equation known as the Drake Equation, named after a famous SETI pioneer, Frank Drake. A discussion of the equation itself can be found here. As you can see, the equation simply multiplies a number of factors together and gives you the number of intelligent species able to communicate within our own galaxy. Sounds simple, and it is, except...

While there's no fault within the Drake Equation itself, the equation relies on a number of unknown factors, so any calculation of the Drake Equation is little more than a guess. Some are fairly well known, but some of the unknowns are: "Mean number of planets located within the continuously habitable zone," "fraction of planets on which life originates," "fraction of planets in which life becomes intelligent," and so forth. These are obviously entirely unknowns at the moment (though the first of these may be fairly well known in the next decade).

So, let's begin by defining what it is exactly, that we're looking for. It is this key factor that for me, is the evidence that we'll never find it. What we're looking for is a species which is intelligent enough to have built, at the very least, some form of radio telescope (or in the case of optical SETI, powerful lasers). This ETI (Extra Terrestrial Intelligence) either knows of or has curiousity about life in the universe because they are intentionally sending a signal out, most likely directly towards us, as these are the only types of signals we could currently detect.

So we've defined two aspects of our ETI: At least as technologically advanced as us, and curious about what's out there. Currently, for what we're looking for, these two conditions have to be met. To meet this first criteria, "at least as technologically advanced as us," we're very likely looking at an ETI that is millions of years ahead of us, if they are "at least" as advanced as us. At some point, I'll put a link to any number of sites that examine the probabilities, but it basically comes down to the fact that, given the time span of the galaxy, chances are they're millions of years ahead if they're a day ahead.

The second part is that they must be curious about what's out there. This would tend to imply though not necessarily, that they'd also be interested in exploring beyond their planet. And this I'll admit, is the weakest point of my argument. If we make the leap that their curiousity would imply an exploratative interest, then we have to accept the fact that they HAVE been exploring for millions of years.

Technology, as many people know, is advancing almost exponentially. It was only yesterday, geologically speaking, that we invented the car. Actually, it was earlier today, to be more accurate. And already we've sent men to the moon and probes beyond our solar system. It won't be long, though probably not in my life time, that we're sending colonies of people out to other planets beyond our solar system. We are a race that thrives on exploration. Nothing in physics says that such exploration is impossible. In fact, with some fairly rudementary advances that could be accomplished with the proper amount of money and a few decades of research, we could easily send such craft out.

Simple mathematics shows that, if a civilization colonizes at a rate that we will easily attain, then they could colonize the entire galaxy in a very short time, geologically speaking. In fact, in a mere 5-50 million years or less. This number makes a very pessemistic assumption as well: It assumes that we advance only slightly from where we are in interstellar propulsion, and then never advance any further. Current physics says this is unlikely. It is far more likely that we will advance much further from where we are. 5 to 50 million years is nothing in terms of the age of our galaxy or the universe. This essentially implies that the first civilization capable of colonizing the galaxy, will.

So, if this is the case, and our ETI friends are millions of years ahead of us, where are they? This is known as the "Fermi Paradox," named after Italian physicist and mathematician, Enrico Fermi. He was pretty good with statistics and this was the question he had. If they're more advanced than us, which probability says with more than a 99% certainty they are, then where are they?

And that in itself is one of the biggest arguments against life on other planets, at least in our galaxy. I'll admit that we're nowhere near being able to travel to other galaxies and the current physics suggests that this may be an impossibility, at least to do it within several hundred lifetimes at the fastest theoretical speeds. I don't think we'll be doing that anytime soon.

Now, I'm going to take the argument one step further, and discuss the possibility of intelligence, given life. Life began on our planet almost as soon as it was possible, given the environment. Prior to life developing, the planet was simply too hostile to contain life and didn't have the proper chemical balance to make life, as we know it, sustainable. Almost the moment this changed, life developped (again, in geologic time scales). The Earth itself is 4.5-4.6 billion years old. That's 4,500 million years. Single-celled life began about 3.8 billion years ago. Yet until 700 million years ago, multi-celled life failed to appear. I think we can all agree that single-celled life will not meet our demands for intelligence.

So, what does this tell us? It says one important thing to me: That multi-celled life does not necessarily follow from single-celled life. That multi-celled life is much more of a gamble, while single-celled life can be taken as a given when the conditions are met. The conditions for multi-celled life to exist, have existed as long as that for single-celled.

Does intelligence necessarily follow, given multi-celled life? I think not. If we assume that human beings are the first and only intelligent life that meets the definition I provided early in this essay, and the earliest forms of our species have only been around for 300,000-400,000 years, that's .3 million out of 3,800 million for the history of life on our planet, or 0.007 percent of the history of life on our planet. That seems to indicate that intelligence is far from a given, but more of an accident.

Dinosaurs dominated the Earth for millions of years, yet never developped intelligence. Crocodiles have existed since the dinosaurs and yet they haven't evolved intelligence. So I think it's safe to say that intelligence does not necessarily follow multi-celled life.

To understand this a bit better, I think it may help to give this simplified explanation of how evolution works. Evolution has one goal, and one goal alone, allow a species what it needs to live long enough to procreate enough to replenish its species. Once this goal is met, evolution doesn't do a whole lot more. There's no need to improve on a species once it attains this goal. We may "want" it to continue to improve, but that's a desire. Evolution doesn't have desires. It simply has a function.