Re: Our rocky solar system may be rare

Chris Watkins (
Sun, 12 Sep 1999 16:31:29 -0700

From: Robert J. Bradbury <> To: <>
Sent: Saturday, September 11, 1999 9:39 AM Subject: Re: Our rocky solar system may be rare

> On Sat, 11 Sep 1999 wrote:
> >
> > But actually assembling some kind of self-replicating
> > system or cycle is still not well understood.
> Given that we get a stable crust ~4 billion years ago and life seems
> to appear at 3.86 billion years ago, that says that (a) it either
> came from space (panspermia); or (b) it is easy.


How about (c) it is the first of a long series of improbable events, and given that we exist now to wonder about it, it must have happened early in the history of Earth? In other words, observer selection. I don't see that we've got enough evidence to distinguish between (a), (b) and (c) yet, at least until we've checked out Mars, Europa, Titan....