Milky Way Inhospitable?

tdfunk writes "Space.com reports that life in the universe may be more rare than previously thought. In an article published today, Space.com quotes Guillermo Gonzalez, an Iowa State University researcher, who has studied the structure of our galaxy and has concluded that life may not be as common as we may have believed. Apparently, conditions around the Milky Way Galaxy are generally less hospitable than once thought.

Comments

Re:Many galaxies

[Bonker]

Our galaxy is around 100k light years across. Assuming we built a craft that traveled .5c, it'd still take over 200k years to cross that... about 20 times longer than human civilization has been around.

The distance between galaxies is an order of magnitude larger. Even if there was life in the Andromeda galaxy, if they started at the same time we did, we wouldn't meet them for millions and millions of years, assuming sub-light travel.

Economists, dieticians, and space scientists

[Infonaut]

why do they all seem the same sometimes?

Economist #1: "The economy is going to collapse this quarter!"

Economist #2: "No! It's on an upswing, you idiot!"

Dietician #1: "Balanced intake of carbs, protein, and fats is best."

Dietician #2: "Uh, yeah, sure.. if you want to look like Rosanne. Max protein, don't worry about the fat, and cut down on the carbs."

Space Scientist #1: "Thousands of life-giving planets are out there. We have the calculations right here. Really."

Space Scientist #2: "Look, dude, the odds of there being other life-bearing planets are almost nil. We have the calculations right here. Really."

I mean it in good humor, but as a layman it sure is difficult to tell which of the astronomers and other guessers are on the right track.

Rare Earth

[RedCard]

If this article interests you, I highly suggest that you get (and read) a copy of "Rare Earth" by Ward and Brownlee, Copernicus press.

In it, they lay out their case for why advanced life is rare in the universe, but simple life may be relatively common. The article that's linked to seems to be a condensed form of the argument set out in Rare Earth.

Rare Earth goes over planetary habitable zones, galactic habitable zones, and also goes much further on about the necessity of a "benevolent" jupiter-like planet, planetary extinction events, and plate tectonics.

I think this book was reviewed on slashdot, but I don't feel like looking it up. It's still one of my favourite books.

BTW: it's not some crackpot theory, either. Ward and Brownlee are both professors at the University of Washington in Seattle and they site 26 pages of scientific references at the back of the book.

--RC

Gamma ray bursts and the Milky Way

[jesterzog]

Space.com reports that life in the universe may be more rare than previously thought

I was recently reading up some more on gamma ray bursters, which are a recently discovered thing with explosions (so far only seen a very long way away) that appear to have an amount of energy equivalent to about the rest of the Universe put together.

There was a paper published in 1999 that theoriesed that every gamma ray burst was a galactic scale mass extinction event, and then attempted to extrapolate a rate that they occur locally in the Milky Way, then going on to suggest that because the rate is slowing down, we might be in a transition period for intelligent life appearing. It's all entirely theoretical, but it's an interesting read.

The good news is "at last we're here". The unfortunate bad news if the theory is correct is that because the last burst is somewhat overdue, we might not be here for much longer.

For what it's worth, there's a hugely massive star (eta carinae) about 7,000 to 10,000 light years away that's arguably ready to blow some time in the next million years. (If you're in the southern hemisphere it's a really nice thing to look at with binocs or better.) It's on the fringes of the theoretical limits of how massive a star can be, it's gone past the theoretical limits of the maximum amount of light that a star can possibly emit, and it's been suggested as a possible source of a future gamma ray burst in the Milky Way. Really though, nobody's quite sure what's about to happen. On the other hand we should probably be hoping that we're not nearby when it decides to go.

It's just another theory.

Re:How do we know what is hospitable?

[John Miles]

Adaptation comes after multicellular life.

There is absolutely no basis for that statement in reality. Although the researchers and doctors dealing with the evolution of drug-resistant bacteria would certainly prefer it that way...