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I have read the some same thoughts on this. I don't have enough information to make the assertion that life is non-viable in those regions. An interesting paper you might enjoy can be found here:

http://www.aip.de:8080/groups/sternphysik/stp/PDFFILES/2000/gaia_paper.pdf

Thanks, I've actually been looking for something a little more definitive on habitable zone forecasting, and that definitely works. This information is useful because, while I don't believe that there are many intelligent life forms in our galaxy, I do believe that there are a large number of human habitable planets awaiting colonization.

I don't have enough information to make the assertion that life is non-viable in those regions.

It's not so much that life is "non-viable" - heck, research on our own planet has showed us that life can pop up in the most unexpected of places - it's that complex, intelligent, multicellular life is unlikely in much of the galaxy. Life of this type requires long burning, metal and hydrogen rich stars. It requires stable orbits. It requires a quiet area unaffected by nearby gravity wells, radiation bursts, or swarms of interstellar debris. Moreover, it requires time...a planet may need more than three billion years before it can raise an intelligent species capable of communication with the stars. There is only one region in our galaxy that meets all these requirements, and that region is contained in a relatively narrow band in the middle of the galactic disk.

The presence of life on planetary bodies outside of this band is indeed possible, but the odds of intelligent life are very, very low. They are so low, in fact, that radio astronomers searching for signs of intelligent extrasolar life would be better off ignoring these to focus their search on the more likely areas first...as astrophysicists and visual astronomers have been recommending for more than a decade.

Wonderful reference! Thank you for including it!

Placemarker.