Tuesday, April 15, 2008

A dated mathematical estimate of technologically advanced civilizations in the galaxy, and it's tangents.

I enjoyed this cute clip where Carl Sagan uses some simple math to estimate how many alien civilizations capable of radio astronomy might exist within the Milkyway galaxy.

Some points of interest:

- At every step, Sagan is able to make a highly conservative estimate (about how many habitable planets there might be, how many with civilizations, etc.) and still retain an excitingly large number -- with one exception. When Sagan attempts to estimate how many civilizations might survive to technology maturity (as opposed to destroying themselves), he finds it takes optimism rather then conservatism to retain any number at all. A fair reminder of how close we have come.

- Sagan uses radio astronomy as the measure, and seems to envision the sort of alien civilizations that have dominated all but the most recent sci-fi. But today, images of enlightened civilizations composed of humanoid artisans and interstellar spaceships seem increasingly naive. Like Sagan, we're able to fuel our imaginations with the science of our time -- modern microbiology, computing, nanotechnology and even the subatomic physics that I understand so poorly. Personally, I find Kurzweil's view both intuitive, and difficult to find challenges for (criticisms of timescale aside). Which leaves my imagination in wondering: What does intelligent matter of astronomical proportions look like? What sort of conditions might allow it to spread explosively rather than gradually? How might we detect this stuff, and if we can't ... what are the implications of that?


Chris said...

I'd say that Sagan takes some liberties with the estimates! I thought I remembered a recent news story where the existence of rocky planets in other solar systems was being actually verified for the first time (visually? By gravitational effect? Can't recall)

The other reference I find lots more interesting, and I think I could offer some views on a couple of the assertions, and on your questions...

I'm hesitant to accept that bigger = more intelligent, even when dealing with building blocks that can't shrink any smaller. Does a bigger lump of matter mean that more complex patterns can be formed in that lump? I'm not sure I'd dare to answer yes to that. Obviously complexity requires some size (can't make intelligence out of a few molecules for ex), but I don't think it's a linear relationship.

"What sort of conditions might allow it to spread explosively rather than gradually?"

I'd say that all life as we know it really does spread explosively! It's limited resources that put caps on our explosions, so maybe the discovery of some quite vast energy resource is the answer.

As for detection of astronomical intelligence... it makes me smile to think that we could very well already be part of the substrate of an complicated pattern that covers the entire universe, and that pattern could constitute an intelligence. Maybe if a supreme computer subsumed all matter and became the entire universe, little eddies inside of it might form societies, and wonder if some day their own creations might expand and expand to fill their entire reality...

(ps, sorry for all the elipses, I'm trying to cut down...)

Chris said...

Here's another random thought about the world engulfing super computer; once an 'intelligence' reached sufficient size, would it ever decide that growing even more intelligent was not in its own best interests and voluntarily scale back?

Rachael said...

I saw that same bit of news -- and to my memory it's a combination of wobble and gas analysis.

All the same, I thought most experts agree that most single and binary systems probably have planets. First because planet formation is thought to be closely linked to star formation, and second because it's more parsimonious to assume our system is typical as opposed to atypical.

While there may be some very good reasons that bigger != more intelligent, I can't think of any myself. It makes sense to me that more space to do work means that more work could be done, the rest is a question of efficiency and quality of the substrate. I'm thinking of The Life Game as an example, a Life world with a larger grid can house more complex patterns than a smaller one - hands down.

About your last question - I wonder that too!

Thanks for your response. :)