Life on Titan?

While watching several documentaries on the solar system, I've often heard it said that the Earth is in "The Habitable Zone." That we are placed in a manner that allows liquid water to exist without it evaporating away or being frozen solid. This has always baffled me to some extent because I know that temperature isn't the only variable when it comes to rendering a gas or solid into a liquid... Venus is a virtual hell with temperatures around 900---°F, but they attribute this to it's thick atomosphere more than it's proximity to the sun. Venus' atmosphere is 90 x that of Earth's. And Mars is on the other end of the spectrum with temps at -200°F and an atmosphere only 10% of Earth's.

... And why is liquid water so important anyway? Could some other liquid be a catalyst for the type of chemical reactions that could spark life? Take Titan for instance... It has vast seas of liquid methane.... On earth, methane exist as a gas... it's natural gas, but on Titan, it's so far away from the sun that methane is in it's liquid from there... -290°F... Scientist believe that there are several chemical reactions occuringon Titan due to it's dense cloud cover...

Is it at all possible that methane could take the place of water for another life form? In addition to methane, there is carbon dioxide, hydrogen, ethane, ammonia and nitrogen... very similar to the chemical make-up prior to life emerging on Earth... or so scientist believe... Could there be organics on Titan? Or at least the beginings of it?

Yes. I believe so.

No--try Europa instead. The movies said so....

In his The Lefthand of the Electron, Isaac Asimov lays out why water is pretty much necessary for life. I don't remember all the details, but you're unlikely to find life on a planet without liquid water. Given how easy it is to find life here on Earth, were it to exist on another planet, I'd say that if there was life on another planet in this system, we'd not have too much trouble spotting it. Even if it was life as we don't know it, it should be easy to spot, as life remakes it's environment pretty handily.

We might find it on Europa, and there's one of Saturn's moons, Enceladus, which has liquid water. If there's life in the solar system besides here, then it's most likely on those planets.

Something to do with water freezing top to bottom instead of bottom-up, I think.

More correctly, the fact that ice is less dense than water. So frozen water will float rather than sink.

Well Titan has several things against it as a source of life (lets define "life" as self-replicating series of different complex chemical compounds bound in one distinct vessel capable of some form of evolution). I think that definition should fit just about any measure of "life" that we might be able to recognize as such.

First - methane isn't nearly as functional as water to serve as a medium to dissolve other chemicals, its not a polar molecule like water is and its hydrogen bonds are weaker than those in water. This means that instead of dissolving other chemicals to make solutions it is more likely to react with them to make something else. That might be just want you want when you're trying to get a bunch of precursor chemicals for life in the same place, but doesn't make it a good environment to keep those chemicals in any sort of stable form.

Second - it is cold on Titan. You have to have some energy in the system for chemical reactions to take place. Though on billion year time tables this energy will be liberated from somewhere; however the "shelf-life" of such compounds has to be weighed against their chances of creation. In other words with less energy into the system less complex chemicals are created, and those that are created don't have as many opportunities to react with other complex chemicals before they are reduced into simpler molecules. In other words we're not going to find [DR]NA on Titan or some comparable molecule.

The interesting thing about the Earth is that it is the only planet right in the area where liquid water would be abundant - the amount of solar radiation hitting the Earth is just right; if we take the Moon as our base since it shares the same orbit and doesn't have enough atmosphere to make a difference - the part in the Sun is roughly 107 C and the night side is -153 C. Obviously our atmosphere keeps water from boiling or freezing and makes life possible here. But when you think about it, that means that the one place in our Solar system where we know that liquid water exists in abundance became filled with life. Part of me wants to think that this means if you've got abundant liquid water then you're pretty much going to have life. The real question is then, how much is "abundant" - there's been quite a bit of talk lately of the "frozen" Earth model giving rise to life as other compounds not only can cause water to be liquid at much lower temperatures but also create areas of liquid water with much higher concentrations of other elements (thus the reason why the water is liquid at a lower temperature). Which means that chemical reactions that do happen actually happen "quickly" compared to what you might see at "room" temperature with lower concentrations of other chemicals.

I just think that if there is life on Titan it would still be water based in some form; perhaps where ever there is frozen water interacting with the methane oceans, but based on water and not methane. It isn't that I don't want to believe in some sort of funky methane-based life; but that the more I learn about chemistry the less I think you could have the complex chemicals required without some sort of water base.

Edit >

And to your last question; I think there are probably all sorts of abundant organic molecules on Titan many don't require all that much energy to create (a little ultraviolet nudge here, a little kinetic push there) I just don't think there are many complex organic chemicals. I wouldn't call a self-replicating molecule "alive"; I wouldn't even call a self replicating molecule with hundreds of carbon rings and thousands of hydrogen bonds "alive" - now a molecule that could change itself to react to its environment while maintaining some ability to replicate itself that was billions of atoms would grudgingly be admitted to be some weird form of life, I just don't see such a thing coming about on Titan.

Even at such an extremly cold temperature would methane still be as willing to release it's hydrogen? If it's so unstable at that temp,then how could vast seas of the stuff exist for billions of years? Lack of entropy?

Its not that methane is unstable at -260C - just that it is more unstable than water regardless of temperature. Methane reacts quicker to oxygen than does water - in fact one of its common reactions is to make water. This means if there's a complex molecule in solution with methane it is more likely that any sort of oxygen based reactions are going to take place with the methane rather than the molecules in solution. That fact right there rules out a hefty percentage of chemical reactions that are found in life on Earth - it actually rules out a hefty percentage of chemical reactions that give rise to complex organic molecules before they're even capable of forming what we'd think of as "life".

So, while yes, at a colder temperature methane (well any...) molecule is less likely to react that doesn't mean there's more likelihood of methane based life - it just means that there's less reactions in total. The methane is less reactive in cold just like everything else; so there's no net advantage to methane (even at extremely cold temperatures) over water as a basis for life.

See, now this kind of attitude just pisses me off. It shows the height of human arrogance. Statements like this should always be qualified by something along lines of "based on current scientific knowledge..."

Because really, when you look at the vastness and wonder of the universe, we know fuck-all.

But then, the man was a biochemist.

I dunno WaB, chemistry works the same way just about everywhere we can see; from inside our own bodies to the interstellar clouds of dust and gas in other galaxies. Certain reactions are simpler and can make interesting and complex compounds and others just simply aren't. Water is one of those amazing "gosh" things - like the weights of various subatomic particles that just simply makes things work the way they seem to work. I don't think it strange or arrogant to say you need "pretty much need" water for life; the "pretty much" leaving about as much necessary for a bit of skepticism which is healthy for any inquiring mind.

To me it would be far more arrogant to claim that there was "almost assuredly" some form of life (or even highly complex chemical precursors approaching [DR]NA) on Titan. (not implying anyone has here though!)

But there is no water at those temperatures... it's rock solid.

And what about silicon based? Or are you saying the Horta was just SF?

Well its 2am and I've had a bit of wine but that is the weird thing about feezing points - they're all based on density and concentration. Skaters move about on ice because the pressure of their skates cause a layer of water to turn liquid, and we clear our roads by upping the concentration of salts on icy streets to lower the freezing point even more than the ambient temperature. The same things happen in nature - they're actually natural processes that we use for our own benefit. Now at -260 degrees I'm not sure that there'd be enough friction or concentration to cause these kind of reactions; and I'm too tired to look for sources atm, but given a planet wide geography and definite signs of large scale movement (Titan has erosion, a fairly dense atmosphere, and some measure of radiation coming from Saturn - though not as much of the latter as Europa experiences from Jupiter) I think that there are probably some conditions where microscopic areas of liquid water do exist that could give rise to some interesting complex molecules. I still don't think that there is any life on Titan; to me there just seems too much go against it; but a few billion years from now when the Sun is in a red giant phase things will be different; perhaps bits of molecules blown out from the dying Earth will seed such places as Europa, Callisto, Titan, and Triton. I can be a hopeful romantic about such things.

Silicon has been proposed as a potential substitute for carbon in living things, not for water.

Well, so far, the laws of physics seem to work the same way everywhere, so I don't think that we can really say that anything is possible. Asimov in his piece goes into great detail about the matter, and covers not only why liquid water is going to be necessary, but also, that really exotic atmospheres are pretty much out of the question as well.

As far as the "wonder of the universe" goes, in reality, it's pretty goddamned boring when compared to science fiction. FTL is pretty much unlikely (and certainly not as easy as SF writers suggest), Lucas's Force doesn't exist, neither does magic, or fantastic creatures like dragons or centaurs, and there's no aliens hanging out in the Jovian system, damn it. I have a feeling that when we finally do encounter intelligent life in the universe we'll discover that the only thing Star Trek got right was the whole "bumpy headed alien" business.

"Heavier-than-air flying machines are impossible." (Lord Kelvin, president, Royal Society, 1895)

"We are probably nearing the limit of all we can know about astronomy." (Simon Newcomb, astronomer, 1888)

"Space travel is bunk" (Sir Harold Spencer Jones, Astronomer Royal of Britain, 1957)

"So many centuries after the Creation, it is unlikely that anyone could find hitherto unknown lands of any value." (Spanish Royal Commission, rejecting Christopher Columbus' proposal to sail west)

"When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong." (Arthur C. Clarke)

"The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' (I found it!) but 'That's funny...' " (Isaac Asimov)

Tell ya what, you find proof that Einstein got it wrong, and I'll see to it you get a Nobel Prize. Notice also that I didn't say FTL was "impossible" only that it was "unlikely." Even if it is possible, I'll lay money that it won't be discovered in the next 100 years.

Well we do know that the speed of light isn't a constant - it is in a vacuum, but it isn't under weird conditions. We also know that instantaneous transfer of some information is possible, but we don't really know how to make use of it yet. Singularities mess with space/time in ways we don't really understand mathematically, much less in ways that we've observed; however they are natural phenomena and they might not even be the most powerful things we know especially if some of Hawkings theories are true.

I have a headach very fascnating thread very fascinating.

Heck, even really fast sub-light speeds are problematic from a physics perspective. Some months back, I was listening to an old radio serial in which characters around the orbit of Saturn were ordered to go to Venus. They replied that they'd be there in about 3 hours. Now, having read Robert A. Heinlein's Expanded Universe, I knew that travelling at 1 gee acceleration, it'd take you two weeks to go from the Earth to Mars, so I knew that to go a greater distance in significantly less time, one would have to be really moving.

To find out the answer, I popped over to the Bad Astronomy/Universe Today Message Board to see if anyone there knew the answer. I was pretty shocked at the results. To go from Saturn to Venus in 3 hours, you'd be travelling at .71c and you'd experience some 5,700 gees! Obviously, no human could survive that, nor do I think that we have any mechanisms which could be subjected to that level of forces and still function. So, just to be able to travel across the solar system in the same amount of time a commercial jet can travel roughly 1,000 miles we have to figure out a way to counteract the forces of inertia, and how to deal with the instantly lethal force that even a grain of dust would have at traveling at those speeds. That's a pretty tough nut to crack. Presumably, if we're ever able to crack it, then FTL will be possible.

Nerds!

I think if we ever really develop an FTL capability it will involve some sort of hyperdimensional travel or a no-shit warping of the space time continuum, within which the craft would still obey Relativistic speed limits.

Then again, our knowledge of physics is pretty off-base as of yet. We have QM, Relativity, and Newton, and we can't get the first and the last to reconcile yet. Until we can, we can't say what's possible and what's impossible.

No... for all we know today, the speed of light is constant. It's quite easy to understand why the speed of light in some sort of medium is lower than in a vacuum: Actually there is just one speed of light, that in a vacuum. Photons propagating in a medium will end up being absorbed by an atom from time to time, though. The atom will spend some time in an excited state and then emit another photon in deexcitation. The lower speed in a medium can be thought of like the lower overall speed of a trip where you take many breaks.

Sadly, no. I take it you speak about all those 'quantum entanglement' experiments. While they demonstrate the so called non-locality of quantum mechanics, i.e. the fact that some properties of a system extended in space take certain values instantaneously once one of them is measured. However, the random nature of quantum physics makes it impossible to use this for information transfer. You end up knowing instantaneously after a measurement what some other guy far away is going to measure, but as your result is determined by chance, there's no real transfer of information.

What theories you are talking about, exactly? The one big thing by Hawking I know of (and the one he's renowned for in the physics community) is a theory about the evaporation of black holes... not some kind of 'imaginary time' dimensions or whatever he talks about in his popular books.

[sorry, DP]

I will repeat something I've said before: I think FTL is possible, and that it will be easier than anyone currently thinks, and that it will come about when some grad student notices a minor discrepancy (or some such thing) and has a forehead-slap "D'oh!!" moment.

Einstein: God does not play dice with the universe.
Niels Bohr: Albert, if God wants to play dice, let him.

I hope we're able to crack FTL travel, but I'm not holding my breath.

I've thought of God as a dollar "scratch-off" lottery ticket deity.
He's in line at Circle K buying a Hustler Magazine, a 40 ounce of Bud Lite,
a cassette tape of "Best of Foghat" and says "hey, grab me one of those Lucky Seven tickets, will ya?"