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View Full Version : Why didn't we evolve in the Andromeda galaxy?



cjackson
2016-Sep-28, 02:00 PM
Andromeda has more stars, mass, and is larger, so is there something special about this galaxy that we came about here rather than there? Should we expect life to be common in Andromeda?

Tom Mazanec
2016-Sep-28, 03:32 PM
We have to be somewhere. We happen to be in the MW. M31 is bigger, but there are spirals bigger than M31.
I have heard (mostly from Intelligent Design and/or Rare Earth type people) that the MW is unusually well structured, with even spiral arms, and that a more chaotic looking galaxy would subject Earth to regular cosmological Mass Extinctions...I don't know about that.

Ken G
2016-Sep-28, 04:13 PM
Bear in mind that it's not just the size of the individual galaxy that matters, it's also how many galaxies there are of that size. Dwarf galaxies have fewer stars, so fewer "rolls of the dice", if you will, but there are a lot of them. So if we were in a dwarf galaxy, we could expect that to be the reason. What we should therefore expect, as a kind of generic hypothesis, is that if you multiply the relative number of galaxies of different sizes by the number of stars in them, you should find that the MW is somewhere near the peak of that result. If you find the distribution instead peaks at huge galaxies, or at tiny ones, and we aren't in either, then you have something to explain, where you might look at other factors like metallicity or galactic events. We showed up over 4 billion years after the formation of our star, and our star took about that same amount of time to show up in our galaxy, so a lot can happen to a galaxy in almost ten billion years. It gives us a lot to think about-- how special is our galaxy, how special is our star, how special is our planet, etc.

John Mendenhall
2016-Sep-28, 04:34 PM
Andromeda has more stars, mass, and is larger, so is there something special about this galaxy that we came about here rather than there? Should we expect life to be common in Andromeda?

Keep in mind, we only know of one small planet with life . . . so far.

Hornblower
2016-Sep-28, 05:10 PM
As an analogy, we could ask why I was born in Washington, DC, when New York had ten times the population.

Delvo
2016-Sep-28, 05:17 PM
Maybe someone did evolve there. But it wasn't us.

Hornblower
2016-Sep-28, 05:29 PM
If I am not mistaken, some biologists believe life at least at the microbe level to be commonplace and perhaps inevitable on planets in favorable zones. Planet Earth, with its combination of circumstances that make long term climate stability over billions of years possible, may be a rare bird, and could have happened anywhere. If, as creationists assert, we are the work of a divine creator, that creator could have chosen the location for inscrutable reasons, without regard to the size of the galaxy.

Noisy Rhysling
2016-Sep-28, 05:55 PM
Andromeda has more stars, mass, and is larger, so is there something special about this galaxy that we came about here rather than there? Should we expect life to be common in Andromeda?

We sort of did: http://extraterrestrials.wikia.com/wiki/Paul

George
2016-Sep-28, 08:11 PM
We should ask our neighbors here in the MW and see if they know anyone over there. Otherwise, if we assume the MW is favored, then it may have something to do with just the right mergers in just the right way in just the right regions here where we are. I would guess there may be more supernovae, and other beasts, in larger galaxies that would be a little more harmful than good. Dynamics might be another consideration. Dwarfs would be on the other extreme since you need metals (atoms > He) to put meat on our bones.

Jens
2016-Sep-29, 01:59 AM
As an analogy, we could ask why I was born in Washington, DC, when New York had ten times the population.

This is precisely the question that I would have posed. Why was I born in New Haven, CT, when New York is a much bigger place? Statistically, I should have been born there or somewhere else with a larger population. So we evolved exactly where we evolved, and there are no ifs in history.

Noclevername
2016-Sep-29, 02:43 AM
Andromeda has more stars, mass, and is larger, so is there something special about this galaxy that we came about here rather than there?

No. The only thing special about here is that we came about here.


Should we expect life to be common in Andromeda?

We don't even know if it's common in our galaxy.

Chuck
2016-Sep-29, 03:09 AM
Maybe all intelligent life forms are wondering, why here? For anyone out there, there are a lot more places that they might have been than places where they are.