Tuesday, June 22, 2010

In Defence of SETI

In the last few weeks I've heard a series of interviews with Massimo Pigliucci as he plugs his newly published book Nonsense on Stilts: How to Tell Science from Bunk. I haven't read the book yet, but I intend to someday. It sounds like a fascinating read. I do have one issue with it, however.

In one of the interviews (I forget which one it was now), Massimo was asked to explain his position on SETI (the Search for Extra-Terrestrial Intelligence). Massimo classified SETI is "almost science", which he justified by saying that although SETI is employing scientific methods in their endeavour, their hypothesis (that extra-terrestrial intelligence exists) is virtually unfalsifiable. They could literally search for a million years without producing a single result, and still not have falsified their hypothesis.

I think that's a fair assessment, and I'm sure most (if not all) SETI researchers would likely agree with it.

But Massimo didn't stop there. He went on to describe the Drake Equation as being an inadequate theory, or even hypothesis. To which my response is "Yeah... so?"

(Before I carry on, I want to point out that Massimo isn't the only one who has advanced the arguments I'm dealing with here. Not by a long shot. I hear these things thrown back and forth between sceptics and other scientists and philosophers all the time. And they make my blood boil every time. I'm only picking on Massimo because his was the straw who broke the camel's back, and inspired me to finally sit down and write this post.)

The Drake Equation is a list of variables which, if each could be assigned an approximate number, should spit out the likely number of intelligent species in our galaxy right now. Some of the variables (by Frank Drake's own admission) are inherently unknowable, such as the average life-span of a technologically sophisticated civilisation. We only have one such civilisation as an example: ours. And by the time its life-span has ended, SETI won't exist anymore.

Others are knowable, but currently beyond the reach of our ability to determine, such as the average number of Earth-like planets around stars in our galaxy. We're getting closer and closer to that one, but we're still a way off.

Frank Drake often recounts the anecdote of his creation of the equation that bears his name: it was an agenda for a conference in the early days of SETI. It wasn't ever intended to to be either a hypothesis or a theory. It's little more than a way of framing the questions to be asked (and hopefully answered) as part of SETI's progress. It's a useful and important way of thinking about SETI, but it's not a hypothesis. SETI's hypothesis is far simpler: "Extra-terrestrial intelligence exists". That's it.

Another common argument Massimo put forward in the interview was this: SETI assumes that all life in the universe must be like us, and they are therefore not looking for anything other than life like us. They're only looking for radio transmissions, and are only interested in Carbon-based life.

This argument is complete bullshit.

SETI researchers will be the first to acknowledge the fact that extra-terrestrial life could take any form. While we know that Carbon-based life works (because the only form of life we know of is Carbon-based), there's no way of knowing how many other forms of life may exist elsewhere in the universe, or even here on Earth. Because we only know of one kind of life so far, that's what we're looking for. When it comes to life forms of some unknown type: how would we go about looking for it? How can you search for something if you don't know what it looks like? Nobody is assuming that all life must be Carbon-based. But nobody knows how to look for life that isn't Carbon-based.

Horta: not Carbon-based

Secondly, SETI isn't only using radio astronomy to search for signals. That was the first tool that was used (by Frank Drake himself who pointed his radio antenna at the sky back in the 60's), and is probably still the most widely used tool for SETI research. This choice is based on two things:

  1. Our atmosphere is opaque to most of the elecromagnetic spectrum. Only sections of the radio and visible light parts of the spectrum can get through largely unhindered.
  2. Radio astronomy is cheaper than optical. It's a lot easier to build giant radio detectors (like Aricebo or the VLA) than it is to build giant mirrors for optical telescopes. And since SETI has always had funding issues, thrift is a virtue.

That said, Optical SETI is a real thing. Nobody's ignoring that part of the spectrum. SETI researchers who can get their hands on funding for it are going at it as hard as they can.

SETI isn't assuming that any intelligent species out there must use radio (or even light) to communicate with us. Once again, they're going with what they know: radio and light. Humans use radio and light for communication, so we know that it works, and there's a possibility that ET would know that too - and might decide to exploit it the same way we do.

Once again, it's a practical concern. Nobody is claiming that ET would only use radio to talk to us. Nobody is even claiming that ET would talk to us at all... we just hope they will, and we hope they'll use something we can detect.

The third claim Massimo made (although less strongly) is that SETI hasn't changed their methods at all since Frank Drake's first attempt in the 60s.

This claim is also complete bullshit.

Although it's certainly true that the biggest weapon in SETI's arsenal is the same one Drake used: radio astronomy, as I've said, SETI has added at least one weapon to that arsenal in that time: Optical SETI. Also, SETI is constantly looking for ways of refining their search: Figuring out new tricks and techniques for optimising their telescope time, and figuring out what they should be looking for.

SETI has been utilising data and ideas generated by the more mainstream ongoing hunt for exoplanets as a guide, and coming up with insightful and hopefully fruitful new methods. For example: spending more time surveying stars that line up with the plane of Earth's orbit around the sun, since inhabitants of those stars would be more likely to have detected our presence through the transit and wobble methods that today's exoplanet hunters employ. And therefore would be more likely to try and make contact with us, if they're so inclined.

The SETI Institute has a whole staff of Phd's whose job it is to figure this stuff out. They literally sit around all day trying to come up with new and useful ways of improving their search, new things to look for, what we should do about it if we ever pick up that signal and being totally awesome.

If you're genuinely interested in learning more about what SETI actually does, as opposed to what the general public opinion about them seems to be, I highly recommend listening to Are We Alone - a weekly podcast and radio show produced by the SETI Institute and hosted by Dr Seth "The Alient Hunter" Shostak.

Ensign Shostak waiting for a signal

And guys, please. Do a little reading before attacking people like SETI. Those guys are far too nice to stick up for themselves. They've got a hard enough job as it is. Can you imagine working in a career knowing that there's a significant probability that you may never find what you're looking for in your lifetime? Especially since finding what you're looking for could be the most important discovery mankind has made ever. Cut them a little slack, okay?