NationStates Jolt Archive

In the Solar system (and around other stars), there is a habitable zone. Too close to the sun, and it is too hot for usable water and life. Too far from the sun, and it is too cold for usable water and life. (generally speaking)

In the galaxy, there is beleived to be a similar habitable zone. Too far away from the center, and not enough heavy elements are available for planets. Too close and an excess of gamma rays (supernovas, many stars close together, etc.) makes life impossible.

In our local supercluster, which is described as a flattened disc with a halo, we are located away from the center. Could there be a habitable zone for superclusters as well? Might we be in it? (links would be appreciated) Or is this just another off-the-wall idea?

No links, but I can't see how a supercluster of galaxies structure has much effect on the local conditions within a galaxy.

--my annoying two bits

I hope not, 'cause then entire galaxys would be completely devoid of life. *shudders*

No.

Gamma rays are rather spread out after a certain point and the distances between galaxies are immense. If the gamma rays can't hurt us from the centre of our glalxy, then the gamma rays from the magellenic clouds aren't going to do anything.

I don't think that's likely, given the distance between star systems, galaxies and the like. Much the way that we're not affected by Jupiter's magnetosphere - it's too far away.

Not necessarily. The problem with humans is that we've got the idea stuck in our heads that life MUST be based upon carbon, and of similar design to us. Who's to say that it might not thrive on gamma radiation, and have adapted itself to soak up and use the massive energy that's put out by them and is so lethal to us? I'd think the same thing would apply with galaxies and such made of different compositions/ratios of elements than our's.

I didn't know there was a real lack of heavy elements away from the center of the galaxy. If there was, I don't see how it would really matter for life. Simple organisms make do with heavy elements disolved in water. Halve the concentration of these heavy elements in the water and you'll might slow the growth of some organisms, but you won't stop them. Indeed, aliens who evolved in a low heavy element environment might consider Earth too polluted with heavy metals to sustain life.

I don't think that's likely, given the distance between star systems, galaxies and the like. Much the way that we're not affected by Jupiter's magnetosphere - it's too far away.

Don't fool yourself bub. Jupiters magnetosphere is modulated to produce Government Mind Control Rays.

I didn't know there was a real lack of heavy elements away from the center of the galaxy. If there was, I don't see how it would really matter for life. Simple organisms make do with heavy elements disolved in water. Halve the concentration of these heavy elements in the water and you'll might slow the growth of some organisms, but you won't stop them. Indeed, aliens who evolved in a low heavy element environment might consider Earth too polluted with heavy metals to sustain life.

The problem would be that it would produce rocky planets only "half" the size (in this situation), which drastically changes the properties of such a planet.

Of course, as pointed out, who's to say life has to follow Earth's rules?

Who's to say that it might not thrive on gamma radiation
I don't know about thriving on gamma rays (perhaps Bruce Banner could explain more about this?), but our ability to tolerate radiation is based upon the amount of radiation our ancestors have been exposed to. Just as you can breed radiation resistant bacteria in the lab, if there were 10 times as much gamma radiation on earth, we would have evolved to handle it.

(And buy the way, I suppose that breeding radiation resistant bacteria would be microevolution, but don't tell me that doesn't mean there's such a thing as macroevolution. Macroevolution is just a lot of microevolution added together. Saying you believe in microevolution but not macroevolution is like saying you believe in small numbers but not large ones.)

Europa is a good place to look for life in this solar system and it has lower density than earth.

Europa is a good place to look for life in this solar system and it has lower density than earth.

That's a moon, isn't it?

I didn't know there was a real lack of heavy elements away from the center of the galaxy. If there was, I don't see how it would really matter for life. Simple organisms make do with heavy elements disolved in water. Halve the concentration of these heavy elements in the water and you'll might slow the growth of some organisms, but you won't stop them. Indeed, aliens who evolved in a low heavy element environment might consider Earth too polluted with heavy metals to sustain life.
See, here's the thing, in astronomical terms, a metal is anything that is not hydrogen.

That's a moon, isn't it?
If there's water there (which there is a pretty strong case for, really) then there coudl easily be life.

Yes.

Stick it in the middle of Jupiter - Volia! Metallic hydrogen!

See, here's the thing, in astronomical terms, a metal is anything that is not hydrogen.

Seriously folks, how is helium like a metal? It doesn't contuct electricity very well at all. It's not ductile, in fact, I can't even get the damn stuff to turn solid. I've never seen it looking shiny. In fact, I've never seen it at all.

I don't know about thriving on gamma rays (perhaps Bruce Banner could explain more about this?), but our ability to tolerate radiation is based upon the amount of radiation our ancestors have been exposed to. Just as you can breed radiation resistant bacteria in the lab, if there were 10 times as much gamma radiation on earth, we would have evolved to handle it.

(And buy the way, I suppose that breeding radiation resistant bacteria would be microevolution, but don't tell me that doesn't mean there's such a thing as macroevolution. Macroevolution is just a lot of microevolution added together. Saying you believe in microevolution but not macroevolution is like saying you believe in small numbers but not large ones.)

lol...I'm tryin' to imagine him as the Hulk giving a lecture. Anyways..I was using that as an example of how extremely different life could be from our accepted definition of it.

Seriously folks, how is helium like a metal? It doesn't contuct electricity very well at all. It's not ductile, in fact, I can't even get the damn stuff to turn solid. I've never seen it looking shiny. In fact, I've never seen it at all.
It's nothing to do with the properties of metals, it has more to do with the original elements of the universe (i.e. hydrogen with trace amounts of helium) versus the elements that are formed through fusion in stars (i.e. everything but hydrogen)

It's nothing to do with the properties of metals, it has more to do with the original elements of the universe
I think you mean everything heavier than hydrogen or helium is a heavy element, not a metal.

Yes, there is very little in the way of heavy elements in old Population II stars, which presumably formed when there weren't many heavy elements around. Anyone know if there are more Population II stars out towards the galaxy rim?

To answer your question about pop II stars, yes, they are more abundant toward the rim -- see following websites about the GHZ.

http://arxiv.org/PS_cache/astro-ph/pdf/0404/0404538.pdf
http://www.spacedaily.com/news/life-01o.html
http://www.sciam.com/article.cfm?chanID=sa003&articleID=00017D43-CFD9-1FF1-8FD983414B7F0000
http://astronomy.swin.edu.au/GHZ/GHZmovie.html

However, my question for all of you is about a possible habitable zone in galactic superclusters (groups of thousands of galaxies) -- do you think there might be a similar effect there? (active reactions in the middle galaxies make life impossible there, for example_

I can't think of any reason why.

Do Berzerkers like the centers of galaxy clusters?

Well I read through the article on galactic habitable zones. And I'm afraid I don't agree with it much. I sounds like a heap of "just so" stories to me. Indeed, the other scientist quoted in the article says that it's bullshit.

"This is a good theory," says Borucki. "I think this idea is a spark that will initiate similar research. Like a spark plug, it can't drive the car, but it provides the necessary impetus to get the car moving."

For those who don't understand scientists speaking on record, it means theres no real evidence to support his ideas.

Being too close to the core will distub the Oort cloud? If you're closer to the core, you don't get a big freaking Oort cloud. You could argue life is more likely closer to the core because the Oort cloud gets cleared out earlier before complex life evolves.

Life evolves to handle the conditions it meets. Higher radiation is not a problem unless it's extreme.

Everytime earth cops a planetary disaster, life comes back bigger and better. I don't wanna sound nasty here, but aren't you glad the dinosaurs got wiped out? Of course, a giant comet impact wouldn't do us a heap of good, but could be damn good for the superintelligent naked mole rats that will replace us.

Massive supernova stars are more concentrated in the spiral arms. Oh wow! I'm so scared. You get about one supernova a centuary in this galaxy, and even one at the distance of Alpha Centauri wouldn't wipe out life on earth. (Again, sort of a major problem for us, but extinction is still unlikely. Planet would be kinda messy though.) Twice the risk of being in a supernova blast radius is still not much of a risk.

There has long been a tendency to consider that the earth holds a special, "sacred" place in the universe. That idea is still hanging around. Just as creationists have had to give up saying the design of our eyes and ears couldn't have evolved through natural selection and are forced to rely on cellular machinary that is easier to lie about, people who believe the earth is special now have to move their arguements out into the galaxy.