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Mr Gorsky
2004-Nov-10, 02:04 PM
Hope this is in the right place, and hasn't been done before - couldn't find it anywhere on the board.

Now, I am not an astronomer or astro-physicist or any other kind of scientist, just an average Joe with an interest in these things, and something has intrigued and irritated me for a while in media discussions on the possibility of finding life on other planets. That something is water.

When these discussions take place, the scientists featured invariably conclude that where there is water there is the possibility of life - e.g. in the theoretically water oceans beneath the ice of Europa, or in deposits of water ice on Mars etc.

Moreover, I have heard some scientists state categorically that life can only be found where there is/was water.

As a layman ... I don't get it.

Given the vastness of this amazing universe, and the incredible things already discovered, is it not conceivable that life could develop without water?

Is it just that we wouldn't have a clue what we are looking for in establishing the existence of non-water evolved life forms, or is there a good scientific reason why life cannot develop without water (which is a pretty definitive statement for a scientist of any description to come out with)?

Thoughts/opinions welcomed.

Thanks,

TriangleMan
2004-Nov-10, 02:18 PM
Here's a link (http://scienceweek.com/2004/sa040206-2.htm) that discusses it. Some have proposed that, though very unlikely, liquid ammonia could be used in place of water to support life. How that would work though I have no idea.

Wally
2004-Nov-10, 02:52 PM
I used to think the same kind of things, such as why we were so stuck on why life couldn't exist in an atmosphere of ammonia, for instance. What I've come to discover is that there's basic, chemical reasonings behind our thinking. We're not carbon-based solely by chance. It turns out carbon, as an element, is able to bind with other elements best (silicon comes a close second, I think). Therefore, any complex organizism will most likely also be carbon based.

I think the same think holds true with H2O. Something about it's chemical makeup makes it ideal for forming complex chains (or something along that nature). In other words, scientists didn't just pick water as a prerequisite for life based on our history. There's good, scientific logic behind it.

Evan
2004-Nov-10, 05:27 PM
Lot of info here:

http://nai.arc.nasa.gov/

John Jones
2004-Nov-10, 05:57 PM
My take on it is this: The only life we know about is on earth, and every earth environment, no matter how hostile, has some form of life as long as there is liquid water present.

But what do I know?

Bozola
2004-Nov-10, 06:17 PM
Though we must recognize that have a carbon/water type life bigotry, it's hard to imagine really wild forms until we actually find them - then it becomes obvious all along.


Here's some off the top of the head points...

Water has some great properties to it

It's three phases can exist in non-extreme conditions.
It has fantastic thermal properties.
It is a great solvent.
It is highly polar; oils and lipids can naturally form spheres.
The product of a hydrogen and oxygen reaction is inert and can be easily transported out of a body.

Carbon is superiour to silicon because the bonds are stronger, and the oxidation product of carbon (in the same conditions as for the triple phase of water) is inert and a gas, easy to remove from a body. The oxidation product of silicon is a solid; far more difficult to get rid of.

Evan
2004-Nov-10, 06:27 PM
The oxidation product of silicon is a solid; far more difficult to get rid of.

Unless the organism also makes silicone oil as a lubricant for the, uh, whatever it uses....

Swift
2004-Nov-10, 06:33 PM
Carbon is superiour to silicon because the bonds are stronger, and the oxidation product of carbon (in the same conditions as for the triple phase of water) is inert and a gas, easy to remove from a body. The oxidation product of silicon is a solid; far more difficult to get rid of.
In addition to bond strength and ability to bond to lots of other elements (as Wally said), carbon has a great ability to form double and triple bonds with itself and other elements. This allows for a great variety of compounds with varying levels of reactivity and structures. Carbon is also excellent at forming long chain molecules (polymers), both natural and synthetic.

Water's unique properties, to a great extent, come from the ability to hydrogen bond (form weak bonds between the oxygen of one water molecule and a hydrogen from another). Though other solvents have this ability (including alcohols and NH3), the bonding is much weaker. This gives a lot of the thermal properties that Bozola mentioned.

Bozola
2004-Nov-10, 07:11 PM
In addition to bond strength and ability to bond to lots of other elements (as Wally said), carbon has a great ability to form double and triple bonds with itself and other elements.

Oh bloody! SP2 orbital hybidization of carbon. I can't believe I forgot that.

Bozola
2004-Nov-10, 07:18 PM
The oxidation product of silicon is a solid; far more difficult to get rid of.

Unless the organism also makes silicone oil as a lubricant for the, uh, whatever it uses....

Are you suggesting that breast implants are actually an infestation of alien organisms?

Evan
2004-Nov-10, 07:43 PM
Based upon certain visuals seen from time to time, especially upon the internet, I think you are on to something. An investigation is in order.:D

(edit)

Upon investigation I have discovered proof of your surmise. These are surely aliens among us as I have never encountered any lifeform that looks like this. I wonder why they are masquerading as representatives of a machine tool company?

http://www.ridgid.com/Tools/Calendar/

Bozola
2004-Nov-10, 09:26 PM
Based upon certain visuals seen from time to time, especially upon the internet, I think you are on to something. An investigation is in order.:D

(edit)

Upon investigation I have discovered proof of your surmise. These are surely aliens among us as I have never encountered any lifeform that looks like this. I wonder why they are masquerading as representatives of a machine tool company?

http://www.ridgid.com/Tools/Calendar/

This would explain much.

Van Rijn
2004-Nov-10, 10:30 PM
Well, I've been refering to Pamela Anderson as a silicon based lifeform for some time.

zebo-the-fat
2004-Nov-10, 10:58 PM
Well, I've been refering to Pamela Anderson as a silicon based lifeform for some time.

yes, but is it intelegent life? :D

Ilya
2004-Nov-10, 11:20 PM
Given the vastness of this amazing universe, and the incredible things already discovered, is it not conceivable that life could develop without water?


Yes, it is conceivable, and yes, some scientists have speculated about life not only without water, but without chemistry -- such as self-organizing magnetic structures inside stars.



Is it just that we wouldn't have a clue what we are looking for in establishing the existence of non-water evolved life forms

Right. If aforementioned magnetic creatures exist inside the Sun right now -- or even in a more accessible place such as Sun's corona, -- we'd have no idea how to look for them, or even recognize one if we were staring right at one. Unless it did something completely "unnatural", and for a long time, such beast would look to us as just another magnetic eddy. Even if it did behave manifestly different from other magnetic eddies, "it's alive!" is not a theory your typical astrophysicist* would come up with.

*Gregory Benford is an astrophysicist and [my personal absolute favorite] hard SF writer. In early 80's he looked at the radio images from the Galaxy's center, which display arcs of positron-rich plasma about 100 light-years across rising out of the plane of accretion disk surrounding the central black hole. His immediate thought was: "This looks artificial." Benford based much of his Galactic Center novels on this observation. To this day, there is no satisfactory explanation to these plasma arcs. Maybe he is right! :)

Swift
2004-Nov-10, 11:30 PM
I wonder why they are masquerading as representatives of a machine tool company?

http://www.ridgid.com/Tools/Calendar/
How best to spread their evil alien machining technology among dumb-struck human males.

mickal555
2004-Nov-11, 09:18 AM
Though we must recognize that have a carbon/water type life bigotry, it's hard to imagine really wild forms until we actually find them - then it becomes obvious all along.


Here's some off the top of the head points...

Water has some great properties to it

It's three phases can exist in non-extreme conditions.
It has fantastic thermal properties.
It is a great solvent.
It is highly polar; oils and lipids can naturally form spheres.
The product of a hydrogen and oxygen reaction is inert and can be easily transported out of a body.

Carbon is superiour to silicon because the bonds are stronger, and the oxidation product of carbon (in the same conditions as for the triple phase of water) is inert and a gas, easy to remove from a body. The oxidation product of silicon is a solid; far more difficult to get rid of.
And, the fact that when water freezes it expands, because of its same mass but larger volume it becomes less dence than liquid DHMO therfore it can float if it could't the whole ocean would just freeze up.

Argos
2004-Nov-11, 01:32 PM
I can imagine intelligent creatures with "hard" bodies - natural electricity conductor crystals forming a crystal brain. Such a solid-state creature would be able to feed directly on the radiation of the parent star, with no need for metabolism, or reproduction.

Arthur Clarke wrote about something like that in one of his short stories (I dontīremember which one).

pghnative
2004-Nov-11, 01:35 PM
And, the fact that when water freezes it expands, because of its same mass but larger volume it becomes less dence than liquid DHMO therfore it can float if it could't the whole ocean would just freeze up.Well, at least the polar portions would.

I think this effect is much more important for life in lakes. And again, only at higher latitudes.

TheGalaxyTrio
2004-Nov-11, 02:50 PM
I'll take a different approach.


Given the vastness of this amazing universe...

...where the laws of physics are identical at every point.

If the scientific commandment states "thou shalt have no life without water", you can expand the Universe to infinity, and not have an exception.

My problem with mechanical or "solid" lifeforms is the question of how they evolve. Ouy very, um... fluidity is what allows us to evolve. Our system makes the occasional mistake, and sometimes it's a good mistake. Yeah, I know people write their little life simulation programs and have little evolving creatures, but they forget that they are playing the part of the watchmaker. Remove the program and what do you have?

Reminds me a Zelazny passage. Imagine a snowflake drifting down a well of infinite height, infinite depth and infinite radius. Now remove the snowflake and consider the drifting.