39 replies to this topic

[eternaltraveler]

microbes appear in the fossil record practically as soon as the Earth was cool enough to permit their existence. However life remained simple for billions of years, only becoming complex late in the game.

This is an incorrect assumption. Life certainly evolved a great deal in those billions of years you speak of, however most of this evolution had to do with life's current exceedingly complex biochemical pathways. It wasn't until some critical point was reached in the biochemical evolution that complex multicellular life could come into play.

[bgwowk]

Perhaps you are right. N=1 is a lousy statistical sample on which to draw conclusions about the probability of biogenesis or evolutionary developments anyway. Still, if biogenesis were a rare event we would on average expect it to occur in the large middle of a planet's lifespan, not the tiny very beginning. It's suggestive that biogenesis may be common. Another possibility is that microbial life evolved long ago, somewhere else, and by some natural mechanism travels through space seeding planets when they are cool enough. If we start finding microbes elsewhere in the solar system with similar biochemistry to Earth microbes, we may never know where they first came from.

By the way, this is a problem with life generally. Once intelligent life starts spreading life and civilization around a galaxy, the origin of it all, like that presumed primordial pond on Earth, becomes the stuff of legend rather obvious physical fact. It's quite possible that civilizations thousands of years from now will be just as ignorant about the empirical incidence of spontaneous biogenesis, and even intelligence, as we are today. They'll find life and intelligence everywhere, and never really know where it came from.

---BrianW

Edited by bgwowk, 30 December 2005 - 06:25 PM.

[bgwowk]

No need to defer to anyone. The observation that speed-of-light limits expansion rate to time cubed rather than exponential is trivial. Drexler wrote that in Engines of Creation 20 years ago, and surely it was noted elsewhere before that.

---BrianW

[jaydfox]

Perhaps you are right. N=1 is a lousy statistical sample on which to draw conclusions about the probability of biogenesis or evolutionary developments anyway. Still, if biogenesis were a rare event we would on average expect it to occur in the large middle of a planet's lifespan, not the tiny very beginning. It's suggestive that biogenesis may be common. Another possibility is...

...that biogenesis is a rare event, typically occuring "in the large middle of a planet's lifespan", but that the typical planet's lifespan is not sufficient for late starters to evolve to sentience. Using the weak anthropic principle (yes, I know, the "principle" is bashed for various reasons...), only on planets where biogenesis occured in the "tiny very beginning" would life evolve enough complexity to make a sentient "observation" of sample size N=1, and hence such intelligent life might mistakenly conclude that (a)biogenesis must be common given how early it happened in their sample.

[jaydfox]

Jay, Brian, you recently suggest that your beliefs aren't inhibiting you. This wasn't clear before.

Quoi?

[jaydfox]

Double quoi?

[bgwowk]

jaydfox wrote:

...that biogenesis is a rare event, typically occuring "in the large middle of a planet's lifespan", but that the typical planet's lifespan is not sufficient for late starters to evolve to sentience.

Excellent point, Jay. I hadn't thought of that, but it makes perfect sense. Early emergence of life is just one more item on the long list of events that have to happen just right for intelligent tool makers to evolve.

---BrianW

[psudoname]

Well, I don't think we know enough to be able to tell which possiblity is more likely, allthough I suspect we are the only technologially advanvced life in the universe. This is because any alien singularities in our past light cone would have affected us, unless they trancend their way compleatly out of the univerce. If the intelligent alien civiliseation fails to start a singularity, then they would probbly die out anyway.

On another less relivent note, if the storys about UFOs are true (which I doubt), then the aliens that have come to earth are almost certainly hostile.

Why? Well firstly although the reports of flying saucers are more impressive compared to current technology, a post-singularity civiliseation could almost certainly come up with something better, and would probly have eaten the earth with nanotech. Therfore the aliens did not have a singularity. This would probbly be because the aliens are religious bioconservatives, and so they would try to stop humans triggering the singularity. Theirfore they are hostile.

But as I said, I doubt earth is being visited by little green men. [lol]