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NEOWatcher
2007-Aug-07, 01:34 PM
I ran across this through the USAToday sight.
Did Man Evolve Because Of Galactic Oscillations? (http://www.scientificblogging.com/hank/did_man_evolve_because_of_galactic_oscillations)


Our sun is not alone in the universe, it travels on a galactic course and, the authors state, the point where it reaches its nearest orbit to other Milky Way stars, it's influenced by galaxies in the constellation Virgo.
Are they really saying that extinctions can be related to our proximity to other galaxies?

Why wouldn't the other Milky Way stars have influence rather than other galaxies?

Or; is this just speculation to ponder?


Is this fact? No, but it will be food for thought in the astrobiology community.

Fazor
2007-Aug-07, 01:40 PM
*Good* food for thought? IMHO it's more like fast-food for thought; maybe a little fun, but horribly bad for you.

Peter Wilson
2007-Aug-07, 04:56 PM
Man evolved because it was bound to happen.

grant hutchison
2007-Aug-07, 05:15 PM
The blog you link to (http://www.scientificblogging.com/hank/did_man_evolve_because_of_galactic_oscillations) is full of gibberish, as can be established by comparison with the original paper (http://arxiv.org/abs/astro-ph/0602092). There is no mention there of any induced "wobble" in either the sun or the Earth caused by distant galaxies.

What the authors propose is that the extragalactic cosmic ray environment is "hotter" on the north side of the galaxy than on the south, because of the relative motion between our galaxy (on the fringes of the Local Supercluster) and the Virgo Cluster (at the centre of the Local Supercluster). This produces a sort of "bow shock" on the north side of the galactic disc.
The solar system cycles up and down through the galactic disc regularly, resonating from north to south under the influence of the planar mass distribution. Each time it bobs north, the authors hypothesize, it bobs closer to the galactic bow shock and takes a hit of high energy cosmic rays. If that happens, than there are a lot of local consequences that might account for extinction events.

Grant Hutchison

NEOWatcher
2007-Aug-07, 05:22 PM
The blog you link to (http://www.scientificblogging.com/hank/did_man_evolve_because_of_galactic_oscillations) is full of gibberish, as can be established by comparison with the original paper (http://arxiv.org/abs/astro-ph/0602092).
The exact reason I asked. Thank you for the interpretation since I had a hard time with the original paper since it was a bit more technical than I was willing to spend time trying to get the gist of.

The opening statement threw me off...

No one is sure why but, since the solar motion through the Milky Way has been computed for the past 600 million years, we know it is too long a cycle for it to be a product of our solar system.

grant hutchison
2007-Aug-07, 05:28 PM
The opening statement threw me off...Yeah. I've no idea what that was intended to mean. The paper itself is very clear that it invokes the (well-known) north-south oscillation in the solar system's orbit around the galaxy.

Grant Hutchison

mugaliens
2007-Aug-08, 08:54 PM
Are they really saying that extinctions can be related to our proximity to other galaxies?

Far more likely extinctions were related to proximity to other stars.

HOWEVER, this information is probably easily extrapolated, at least over the last billion years or so...