RE: Scientific American article on GHZ

From: Don Klemencic (
Date: Tue Oct 09 2001 - 22:00:25 MDT

For anybody who missed the connection, Donald Brownlee and Peter D. Ward are
the authors of the book, Rare Earth, previously discussed on this list. The
book of course goes into these issues in much greater detail. The hardback
edition has been remaindered and is selling at Amazon for $8.25. There
doesn't seem to be a paperback edition, so it may disappear in a while.

                                Don Klemencic

> -----Original Message-----
> From:
> []On Behalf Of Technotranscendence
> Sent: Sunday, September 30, 2001 5:32 PM
> To: Extropy
> Cc: TH
> Subject: ET: Scientific American article on GHZ
> October 2001's _Scientific American_ has an article that consolidates on a
> popular level some of the explanations for the Fermi Paradox.
> See "Refuges
> for Life in a Hostile Universe" by Guillermo Gonzalez, Donald Brownlee and
> Peter D. Ward. (It's not online, but the issue contents are at
> There are few points they make, including that only certain conditions are
> right for forming earthlike planets, particle and electromagnetic
> radiation
> is too high in many of the places where they could be formed, and other
> factors in the galactic environment might make complex life less likely.
> Only a narrow region of the galaxy has these conditions. They
> call this the
> Galactic Habitable Zone (GHZ).
> An underlying assumption here seems to be that earthlike worlds are needed
> for life to arise -- at least for complex life to arise. This
> does not seem
> an unreasonable one.
> There are several other assumptions in the article, though the
> authors note
> and answer many of them.
> Any comments?
> Daniel Ust
> "Macroeconomics for the Real World" is now online at:

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