Saturday, July 03, 2010

Book Review - The Eerie Silence

Awhile back, I wrote a review of Perfect Rigor by Masha Gessen. It was ok. Not the most thrilling read I'd had. The publisher found my review and suggested that another book from their company might be more up my alley. So they sent me a review copy of Paul Davies The Eerie Silence. This book is a 50 year retrospective on the SETI program, written by the head of it's post detection taskforce.

The role of the post detection taskforce is to lay out the recommended policy for the procedure to follow if we ever do discover any sort of extraterrestrial life. But the book isn't about what we'll do, it's about why we haven't found any yet and what possible improvements can be done to improve the program in order to up our chances of actually detecting something.

The main argument of the book is that we've been far too narrow in both our methods of looking as well as our definition of life and intelligence.

One of the first things Davies asks is how likely is it that there is some other form of life out there? We know all life on Earth had a common origin, so we've really only got one example to study and try to understand. Small number statistics impress no one (aside from the pseudoscientists). Thus, to even begin to get a reasonable predictive handle on such things, we'd like to try to find another example of life. SETI could stumble across this in the heavens, or it's possible that it's right here on Earth.

Davies suggests that we look for forms of life on Earth that don't use the same base pairs (or amino acids) that life as we know does. Or life that has an opposite "handedness" (chirality) to it. If these were discovered, it would likely imply a second example of biogenesis and we could start getting a feel for how likely life is to originate in the first place. Although attempts have been made to look for such life (by looking in the most extreme environments in which "normal" life was not expected to exist), the only life that's been found has always been of the same base pairs and the same chirality.

But even without forming full fledged life, Davies points out that amino acids are plentiful in space, including ones that aren't used for life as we know it, as indicated by the Murchinson Meteorite.

Of course, even if weird life were discovered here on Earth (or in rocks from space) it doesn't necessarily prove a completely separate biogenesis. While it would lend credence to it, there's always the possibility that it came from a different branch of our own evolutionary tree or due to some sort of horizontal gene transfer. This would obviously muddy the waters.

On top of that, Davies suggests that looking for odd lifeforms like this may be another way to find messages from extraterrestrial civilizations. ET may use life as a carrier since it's essentially a self sustaining message that can propagate itself. And even if not life, then perhaps nano-machines that can self replicate to spread. Such methods would be more enduring than a short radio message.

If this all starts sounding too close to Intelligent Design, Davies is quick to assure us it's not. In fact, one of the very first parts of the book discusses the difference between good science and pseudoscience, namely that good science must actually work through the math to show just how closely the evidence fits the hypothesis through use of Bayes rules. Although the Discovery Institute is desparate to be similar to SETI, they've never done any such analysis, or even made a hypothesis to be actually testable.

Davies concludes by briefly discussing the post detection sequence, affirming an open and honest dispersal of the information, but a quiet one so as not to get the media all fired up over the possibility of a false positive (as they have before). After all, we've seen the devastation that the media misportraying science can have of the public view with the recent "Climategate" nonsense.

Overall, this book was pretty good. The extreme edge of what Davies proposed (super computer AI taking over in place of life, growing into quantum computers and living in deep space, not communicating with the outside world), goes a bit beyond the believable, but that's the point. We don't have enough information to truly make any good predictions about intelligent life so we need to keep an open mind and open eyes.


Chet Twarog said...

As a mbr of the Planetary Society, just got a ltr to help contribute to fund a revolutionized "Optical SETI" because 'there might be a 'Galactic Club' out there.
Well, I must agree the technology might improve astronomical science research and/or make some new discoveries, but I am quite skeptical that there's some "Galactic ET Club" out there. Geeze, we have a really difficult time with just Homo sapiens "intelligence" on Spaceship Earth.
By the way, the sun, moon, stars do not "come up/go down" or "rise/set". Earth's rotation brings them into view/sight and out of view when the horizon "clipses" them (R. Buckminster Fuller). We're still too earth=centric.

viggen said...

Davies suggests that we look for forms of life on Earth that don't use the same base pairs (or amino acids) that life as we know does. Or life that has an opposite "handedness" (chirality) to it.

While I see what he is suggesting, I think his suggestions are way too narrow to point toward a secondary origin of life.

Some "non-conventional" nucleic acid base pairs are very common in terrestrial life, including inosine, which shows up as a "wobble" pair in transcribing mRNA codon triplets using tRNA (this occurs in humans!). Known microbial life has all sorts of weird bastardizations to the conventional genetic inheritance model, some so much so that you can't always easily move a gene from one organism to another and assume it will be properly transcribed in the new host. This is a common technical problem in restriction cloning.

Also, "backwards" D-amino acids are commonly used in some microbes, including the well-known pentapetide cross-link present in gram-positive bacteria peptidyl glycan which is the target of the antibiotic penicillin.

Because known life already demonstrates these qualities, a new life form that shows these qualities is not necessarily the result of a parallel but separate genesis.

If he wants to convince me of a separate genesis, I would expect to see a demonstrated naturally occurring genetic algorithm involving unfamiliar, possibly unrelated chemistry. This means possibly a fundamentally different scheme of containing and passing heritable information-- genes not made of DNA, if you will. Heck, some viruses package genes exlusively in RNA and some biological phenomena are known that have a non-genetic inheritance-like pattern, including prions-- and these are both products of our genesis of life.

Gotta forgive the guy, though. I think he just has no idea how far he's got to go in order to get to the true primitive, progenator life... which may not exist on our world any more and maybe has not existed for billions of years. What arose first may well have been wiped out completely by the more highly evolved, more competitive forms that came later, or maybe even was destroyed by its own biproducts (Oxygen, for instance). I expect that his specialty is telescopes and radio signals rather than actually breaking free of the paradigmatic (and highly restricted, possibly exclusively terrestrial) view of what life actually is.