OT: Extrasolar planets discovered directly

[Renegade 13]

It's kinda hard to have an arguement when, since Atrocities dropped out of the conversation, all the opinions expressed have been agreeing with each other!

[narf poit chez BOOM]

Oh well. It was fun while it lasted.

[Renegade 13]

Hunpecked you make good points. The only problem with imagining the different forms that silicon based life (or, to be honest, life based on anything other than carbon) is that the imagination of humanity is actually limited to a certain extent to what we are already familiar with. We can not imagine what form a silicon based life form would take since we are not familiar to any great extent with silicon-based life-forms. We say life "would/could not exist" in certain situations, but do we really know?

Also, just because life on Earth favored the development of carbon-based life-forms does not mean that another planet, with similar metallic ratios would not favor another, totally different approach to forming life.

And all of this leaves out the idea of a supreme being (God). If, as some believe, the universe was created, then God could have created whatever forms of life based on whatever elements he wanted to. But I think that's all I'll bring religion into this thread, as we all know that religious discussions can quickly degenerate.

[narf poit chez BOOM]

We would simply have to try to construct a silicon-based ecosystem, down to the molecular level.

It would simply take a while.

[DeadZone]

We've already discovered organisms that live and breed in acid pools (something like that anyway)

So the theory that all life must be Earth life (ie. oxygen & water) has already been proved false
Oh and too the fact that planet life consumed Carbon Dioxide, means that a Carbon Dioxide planet could easily support some form of life

There is no doubt in my mind that life can exist out there, its just a case of whether sentient life has yet to develop out there that I wont make up my mind until its proven either way

[Hunpecked]

We've already discovered organisms that live and breed in acid pools (something like that anyway)

So the theory that all life must be Earth life (ie. oxygen & water) has already been proved false

Well, even the creatures that exist under (for us) extreme conditions on Earth are still based on carbon, water, nucleic acids, etc. In other words, they're variations on a theme, but not a new theme.

There is no doubt in my mind that life can exist out there, its just a case of whether sentient life has yet to develop out there that I wont make up my mind until its proven either way

As long as even a little corner of the universe remains unexplored, the existence of alien life/sentience can't be disproven. So despite the skepticism of some, an enthusiast for ET's can only be proven right, never wrong.

[Hunpecked]

Certain considerations suggest that the odds of finding a contemporary alien technological civilization in our galaxy are less than we might think. Far from being typical, our solar system may be a very special place:

Only a fraction of star systems are "friendly" to life as we know it. Blue/white giants burn out much too quickly for life to become established on any orbiting planets. Altair, for example, would be a poor prospect, despite its being the (fictional) home of the Krell in the film "Forbidden Planet." Red dwarfs, which I understand are much more abundant than Sol-like stars, have such a narrow "habitable zone" that planets are unlikely to remain within it year-round. Most stars are part of multiple-star systems, most of which will have no habitable zone whatsoever. Planets orbiting single stars that are more variable than our sun may suffer extreme climate variations that make even primitive life unsustainable.

It's been suggested in recent years that Jupiter and Saturn are exactly the right size in exactly the right orbits to sweep up space debris that would otherwise cause much more frequent mass extinctions on Earth.

Planets with more axial tilt than the Earth may suffer yearly climate variations too extreme for "higher" life forms to develop. Supposedly our unusually large (relative to its primary) moon helps stabilize the Earth's axis.

Speaking of the moon, I recall a Larry Niven story based on the premise that the moon facilitated life on Earth by sucking off some of our dense early atmosphere, which otherwise would have made the planet a "greenhouse" similar to Venus. I can't vouch for the scientific validity of this concept. I also recall an article by (I believe) Isaac Asimov in which he suggested that tide pools (the moon again) may have acted as a crucial transition zone in the evolution of air-breathing animals.

Our galaxy may have a "habitable zone" analogous to the zone around a star. Too close to the galactic center, and an otherwise habitable planet may be periodically sterilized by supernovas, radiation bursts, etc. from the relatively dense population of nearby stars or the black hole at galactic center. Too far from the center, and the abundance of "metals" (elements with atomic number above 2) may be too low to produce stellar systems with such life-essential elements as carbon, nitrogen, and oxygen. Depending on the width of this zone, the vast majority of our galaxy's stellar systems may be unsuitable for life on this basis alone.

Life apparently developed on Earth as early as 3.5 to 4 billion years ago, but remained "primitive" until about half a billion years ago. This suggests that under the right conditions the odds of developing life are high, but development of "higher" life forms is much less likely. This idea was used in the film "Mission to Mars", which explained the so-called "Cambrian explosion" of complex life forms as alien seeding.

Some of these ideas (and others) are discussed at

http://www.spacedaily.com/news/life-00z1.html

[Slick]

Don't give up just yet.

[Atrocities]

Hunpecked said:
Certain considerations suggest that the odds of finding a contemporary alien technological civilization in our galaxy are less than we might think. Far from being typical, our solar system may be a very special place:

Only a fraction of star systems are "friendly" to life as we know it. Blue/white giants burn out much too quickly for life to become established on any orbiting planets. Altair, for example, would be a poor prospect, despite its being the (fictional) home of the Krell in the film "Forbidden Planet." Red dwarfs, which I understand are much more abundant than Sol-like stars, have such a narrow "habitable zone" that planets are unlikely to remain within it year-round. Most stars are part of multiple-star systems, most of which will have no habitable zone whatsoever. Planets orbiting single stars that are more variable than our sun may suffer extreme climate variations that make even primitive life unsustainable.

It's been suggested in recent years that Jupiter and Saturn are exactly the right size in exactly the right orbits to sweep up space debris that would otherwise cause much more frequent mass extinctions on Earth.

Planets with more axial tilt than the Earth may suffer yearly climate variations too extreme for "higher" life forms to develop. Supposedly our unusually large (relative to its primary) moon helps stabilize the Earth's axis.

Speaking of the moon, I recall a Larry Niven story based on the premise that the moon facilitated life on Earth by sucking off some of our dense early atmosphere, which otherwise would have made the planet a "greenhouse" similar to Venus. I can't vouch for the scientific validity of this concept. I also recall an article by (I believe) Isaac Asimov in which he suggested that tide pools (the moon again) may have acted as a crucial transition zone in the evolution of air-breathing animals.

Our galaxy may have a "habitable zone" analogous to the zone around a star. Too close to the galactic center, and an otherwise habitable planet may be periodically sterilized by supernovas, radiation bursts, etc. from the relatively dense population of nearby stars or the black hole at galactic center. Too far from the center, and the abundance of "metals" (elements with atomic number above 2) may be too low to produce stellar systems with such life-essential elements as carbon, nitrogen, and oxygen. Depending on the width of this zone, the vast majority of our galaxy's stellar systems may be unsuitable for life on this basis alone.

Life apparently developed on Earth as early as 3.5 to 4 billion years ago, but remained "primitive" until about half a billion years ago. This suggests that under the right conditions the odds of developing life are high, but development of "higher" life forms is much less likely. This idea was used in the film "Mission to Mars", which explained the so-called "Cambrian explosion" of complex life forms as alien seeding.

Some of these ideas (and others) are discussed at

http://www.spacedaily.com/news/life-00z1.html

Thank you. You put into word the many things that I have seen that had conviced me that we are a rare accident out side the normal plan of the universe. Thank you.