UEA Research Shows Oceans Vital For Possibility of Alien Life

An anonymous reader writes New research at the University of East Anglia finds that oceans are vital in the search for alien life. So far, computer simulations of habitable climates on other planets have focused on their atmospheres. But oceans play an equally vital role in moderating climates on planets and bringing stability to the climate, according to the study. From the press release: "The research team from UEA's schools of Mathematics and Environmental Sciences created a computer simulated pattern of ocean circulation on a hypothetical ocean-covered Earth-like planet. They looked at how different planetary rotation rates would impact heat transport with the presence of oceans taken into account. Prof David Stevens from UEA's school of Mathematics said: 'The number of planets being discovered outside our solar system is rapidly increasing. This research will help answer whether or not these planets could sustain alien life. We know that many planets are completely uninhabitable because they are either too close or too far from their sun. A planet's habitable zone is based on its distance from the sun and temperatures at which it is possible for the planet to have liquid water. But until now, most habitability models have neglected the impact of oceans on climate.'"

Comments

Correction

[halivar]

"Vital For Possibility of Earth-like Alien Life"

A lot of assumptions there.

Re:Correction

[Thruen]

I wish I had mod points. Every time I hear about planets not being able to support life, this is my first thought. While it's possible that there's no radically different life forms in the universe, until we actually go out and see it, we don't really know. I'm not even sure if we should call it unlikely until we've managed to examine the planets outside out solar system more closely. Don't get me wrong, I'm not expecting it and I'll be amazed if we find anything so different from ourselves, but I don't think we should rule out the possibility.

Re:Correction

[gstoddart]

but I don't think we should rule out the possibility

Not only shouldn't we, we simply can't, because we have no way of knowing.

There is no scientifically valid way to rule out life forms which are unlike our own, because we don't know what they would require or thrive on.

The same as when people say "but why aren't we searching for life which is unlike us", the answer becomes "because we don't know how". There's no basis on which to conclude anything other than "well, we couldn't live there".

At best, we can say a planet is uninhabitable by us, but we really cannot say it is uninhabitable by life we can't even imagine and which is significantly different from what we know.

Anybody who tries to tell you there is no chance of life as we don't know it existing someplace is saying much more than they actually know.

Re:Correction

[timeOday]

Although, the more similar the lifeform is to us, the more likely it is to actually matter to us. If it is sub-intelligent, then it might meet some definition of "life," but would have no impact on life here. The other direction is more interesting though - what if it's way beyond us? In that case we must ask why it either did not find us first, or chooses not to interact with us.

Re:Correction

[Iamthecheese]

Even on Earth there are a lot of creatures that can survive conditions far outside the normal range.

Re:Correction

[gstoddart]

If it is sub-intelligent, then it might meet some definition of "life," but would have no impact on life here.

Oh yeah, what if they're tasty? Some Cerulian maple-bacon pig or something. ;-)

But, more importantly, if we find life on another planet (or wherever), of any form, intelligent or not, that in and of itself would have a huge impact on life here even if we couldn't get there.

Because the answer to "is there life anywhere else" will have been answered, and the people who loudly say there is only life on this planet will be proven wrong.

And, if we know there's like here, and then confirm there's life elsewhere ... given the size of the universe, you would more or less have to conclude that life is pretty widespread.

Even if it was unintelligent, the discovery of life elsewhere in the universe would be utterly monumental in a lot of different ways.

To me, I don't think you can overstate just how big of a deal that would be. Because it would be a complete game changer in a lot of ways, and lay rest to the notion that Earth is singularly unique in that regard.

I just don't see such a discovery having 'no impact'. Not even a little.

Re:Correction

[Triklyn]

the way we know that life adapts is gradual. and energy, while necessary can also be pretty damn detrimental to stability.

while it's possible to say that life can develop in vastly different environments than what we experience here on earth, we don't have infinite resources to use in "exploring" these. We know life has developed on an earthlike planet. :) cutting down the number of planets to only "earth like" ones... still leaves us with too many to ever hope of getting to.

Re:Correction

[the gnat]

I wish I had mod points. Every time I hear about planets not being able to support life, this is my first thought.

And every time a story about extraterrestrial life gets posted on Slashdot, several dozen people say exactly the same thing, as if they've had some brilliantly original insight that the scientists researching the subject missed. No one is explicitly ruling out the possibility that there are gaseous lifeforms living in the clouds of gas giants, or silicon-based rock monsters like the one in Star Trek. Hell, it would be a huge discovery if we found something like that. But since we're presently incapable of observing such lifeforms firsthand, and have no idea what we should be looking for at a distance of light-years, we have to settle for looking for the planetary "signatures" of temperature, oceans, oxygen content, etc. It may not satisfy the pedants, but it's still extremely difficult by itself. When we're capable of actually exploring other solar systems directly, then maybe we can start to look for fantasy lifeforms on frozen airless rocks and methane clouds.

Re:Correction

[K. S. Kyosuke]

There is no scientifically valid way to rule out life forms which are unlike our own

I'm pretty sure there are ways to constrain the range of possibilities. One obvious thing is that no life forms will most likely be based on xenon or gold because these elements don't really form the same kind of a wide range of interesting compounds that carbon does. The laws of physics (and chemistry) are the same pretty much everywhere, and just because our brains (and computers) are incapable of reaching more significant conclusions on this issue at this very moment doesn't mean that it's going to stay like that forever.

Re:Correction

[timeOday]

Well, what specifically would be changed by the discovery of non-intelligent life? Some astrobiologist says, "based on spectrum analysis we think their is an exchange of gasses on planet X indicative of biological processes." Over the next 15 or 20 years there is more data collection and analysis and gradually more people become convinced. But it is still a hundred light years away.

Admittedly I am more of a critic of how people will react than a predictor of it. Many people still see landing on the moon as the pinnacle of human achievement and again, I argue, how so? What did it accomplish or change? Not much. There is something I don't see about how people perceive things.

Re:Correction

[Immerman]

>still leaves us with too many to ever hope of getting to

Pessimist. If we develop interstellar travel, even at small fractions of light speed, remain expansionistic, and avoid completely eradicating ourselves or transcending as a species we could colonize the whole friggin galaxy in only a few billion years.

Or maybe you meant "we" in a personal sense in which case yeah, barring the surprise development of feasible near-instantaneous (in ship-time of course) travel, we have absolutely no hope of visiting more than the planets in our own system and maybe those of one other star.

Re:Correction

[Applehu Akbar]

When we have rovers that can drill into the icy moons, we will be able to test that idea right in our own solar system.

Re:Correction

[The Grim Reefer]

"Vital For Possibility of Earth-like Alien Life"

A lot of assumptions there.

We can't even communicate with other species here on Earth in the same Class as us. Elephants, whales, and dolphins show signs of intelligence. Certainly enough to communicate with each other. And we've hunted species of two of them to the verge of extinction. The Great Apes are in the same Family as humans and we can't have a meaningful conversation with them. Perhaps they are simply too primitive. Or maybe we aren't as smart as we would like to believe.

A non-terrestrial species may communicate using some form of telepathy or chemical component. That would be fun to try to figure out. Or use gravity waves over long distances. What if they are silicone based and live for thousands of years. It could take them 3 days to say hello using subsonic vibrations.

Until 20 years ago we didn't even know that Elephants could use bone conduction through their feet to listen to subsonic calls from other elephants that create seismic vibrations. Or that they also had cells in their feet that are able to pick up vibrations in the ground.

ET could be screaming at us right now and we don't even know.it. The messages could have been sent through cosmic radiation and is encoded in cancer cells. They may have thought that would be the easiest way to get our attention and we just haven't picked up on it yet.

Re:Correction

[Triklyn]

:) any fraction of lightspeed would be a monumental achievement. And, as a pessimist i imagine that the time it takes to wipe ourselves off the face of the earth is shorter than the time it takes to get all interstellar with ourselves.

as we get closer to wiping ourselves out, the time it takes to getting interstellar with ourselves increases :)

though, we could do a generational colony ship dealio, but one way trip and eminently hazardous...

Re:Correction

[Immerman]

Well, for starters if we discovered a convincing atmospheric evidence of life then I would bet that launching a gravitational-lens telescope for a closer look would become a major priority. Even it if could only resolve planetary surface features to a few meters the spectroscopic data alone would provide enormous amount of information, including a *lot* of information on the specific local biochemistry. A great deal of the science we're only beginning to do on our own planet thanks to orbital monitoring could also be done to an exoplanet with the help of a gravitational telescope. How useful that knowledge might be is difficult to judge beforehand, but at a minimum it would give us a much better idea of how common life is in the universe. And perhaps more to the point - until we've got that level of magnification it would be virtually impossible to begin determine whether or not the life was potentially intelligent unless we were lucky enough to be able to establish communication.

And of course once we have a gravitational telescope there's no telling what *else* we might see with it. Granted at 550+AU from the sun it would be constrained to examining a tiny fragment of the night sky, but we would be able to see further and with far more detail than any telescope to come before it. Quite likely we could look all the way to the edge of the potentially visible universe, to the first moments after the universe became transparent. And of course we'd be seeing everything more recent in completely unprecedented levels of detail as well. ~14 billion years of astrophysics on display, much of it at far greater detail than what our best telescopes can currently resolve around even the nearest stars. If that doesn't reveal a potentially ground-breaking secret or two about the universe I don't know what will.

As for the moon landing - in and of itself I would say its significance is more symbolic than practical, but symbolism can be extremely powerful - after all one of the primary things that separate our species from other animals is the facility with which we can harness symbolic thought. On a more mundane level rising to the challenge spawned several other benefits - dramatically stimulating the evolution of the transistor to a viable earth-side technology for example. Introducing photos of the Earth from space, and the unifying awareness that helped promote. Not to mention the frustration it promotes in space enthusiasts to think that we were on the cusp of spreading out into our solar system before the collapse of the Soviet Union removed the political will for such morale-boosting endeavors. The baton may have been dropped for a generation, but it is being picked up again, and you can thank that in part to the fact that we proved it could be done before losing our will to do so.

Re:Correction

[itzly]

Or maybe you meant "we" in a personal sense in which case yeah

You need quite a wide reaching definition of "we" if you want to include many different colonists, spread out over radically different planets, evolving over billions of years. Only a few dozen million years ago "we" were small furry rodents.

Re:Correction

[Immerman]

We don't even know for sure that it arose on this one. Panspermia could easily have spread the seeds of life throughout our galaxy, in which case the relevant question is how hospitable is the planet to the sorts of extremophiles that could survive the journey? And how genetically diverse and evolutionarily flexible is the life that survived the trip, especially in regards to stabilizing and fertilizing the planetary ecosystem it finds itself in?

Re:Correction

[Anonymous Coward]

No one is explicitly ruling out the possibility that there are gaseous lifeforms living in the clouds of gas giants, or silicon-based rock monsters like the one in Star Trek.

Actually, we know almost all basic chemistry, and the range of (stable) molecules that silicon can form is orders of magnitude less than for carbon.
There is a lot of silicon to be found on/in the surface of our planet (over 900 times more than carbon), and yet lifeforms here didn't integrate it in their core chemistry. At most they used it to reinforce surface/skeletal structures.
It also doesn't readily form gaseous molecules like carbon does (CO2), which would help in energy cycles.

Re:Correction

[the gnat]

Actually, we know almost all basic chemistry, and the range of (stable) molecules that silicon can form is orders of magnitude less than for carbon.

Well, yeah, but I didn't want to offend the pedants even further. Unless the laws of physics (and therefore basic chemistry) are very different elsewhere in the galaxy, it's not unreasonable to think that carbon-based, liquid-water-dependent lifeforms are the most probable. In fact, I'd be willing to bet a tidy sum of money that the overwhelming majority of unique forms of life are not terribly dissimilar from ours as far as the underlying chemistry is concerned. They might be fantastically alien in all sorts of other strange ways, but they'll still be based on simple organic polymers. But this is still irrelevant to the discussion at hand, because even if there were different forms of life, we have no idea how we might detect them at astronomical distances.

Re:Correction

[khallow]

There is no scientifically valid way to rule out life forms which are unlike our own

1) Life will require energy flow. More fully, life will operate much like a heat pump tapping energy flow between a high entropy or temperature sink to a lower entropy or temperature sink.

2) Life will require an environment it can survive in. This story attempts to address part of that with the idea of climate buffering.

3) As K. S. Kyosuke noted in his reply, life will require some matrix capable of the complex morphological structures and behaviors that life will need to survive.

4) Life will need time or a shortcut (like a creator) in order to develop. Evolution-based life will need time (measured in generations) for adaptation to occur.

For example, let's take an isolated "rogue planet". First, it's an object massive enough to round itself under the force of its own gravity, but not massive enough to undergo fusion. Second, it's not orbiting a star and basically is slowly cooling down to the temperature of the cosmic microwave background (no external energy inputs of note). The driver for any life would have to be heat flow from the interior due to heat of formation and possible radioactive decay. The situation is contrived (but in a way that actually probably appears billions of times in nature, just in our galaxy) so that there is no other means to provide significant energy flow to the system.

Restriction 2) is rather simply solved since the environment is very stable over billions of years (unless the rogue planet happens to get too close to a star or runs into something).

Restriction 3) requires either complex chemistry (from elements other than hydrogen or helium) or structure from say possibly, the interaction of different phases of metallic hydrogen and electromagnetism at the core of a gas giant.

Restriction 4) means that if it's evolution-based life derived from abiogenesis, then it needs to be in a high enough energy flow over large enough volume so that enough generations can pass to evolve to a state where they can technically qualify as life (such as traits/information passed from past organisms to future ones). We don't know how big that would need to be, but bigger and older is better. Similarly, we would need the presence of complex structures, which are more likely in a high energy flow environment (eg, amino acids created by weather-induced lightning).

If it's creator-derived or evolved elsewhere and migrated, who knows. The resulting organism might be able to fuse deterium and/or helium 3 isotopes, for example. That allows for creation of higher weight elements too.

Re:Correction

[Immerman]

Hmm, now you've got me curious just what it would take. Let's see... human energy consumption in 2008 ~=144,000 TWh = 5*10^20 Joules
E = 1/2mv^2 (for negligibly relativistic speeds), therefore
m = 2E/v^2. And if we're looking to get to 0.1c that gives us...
m = 2*5e20/(0.1c)^2 = 1,112,650 kg

So given an acceleration system that requires minimal reaction mass, with the amount of energy we consumed in 2008 we could get a 1000 metric ton craft up to around 1/10 lightspeed. Eminently doable if we had the political will to attempt it, and the (few) passengers could reach the nearest stars in a single generation.

Of course for colonization with near-term tech we'd probably want to make large generation ships, which would increase the energy needs considerably. Still, a decent fusion reactor and some powerful ion drives should make it viable, and both of those are currently hovering on the edge of viability. And of course if we ever manage to find/make magnetic micro-singularities then mass-conversion reactors become an easy source of near unlimited energy, and such things become almost inevitable. Hmm, let's see: 5*10^20J/c^2 =~ 5,563 kg. Not too shabby, a 200:1 payload to fuel ratio to accelerate to 0.1c. Of course your reaction mass is going to dwarf that... and sadly Google won't cough up any thrust-to-energy ratios for a "radio drive" - I seem to recall they're expected to be terribly inefficient, but with mass conversion for power the lack of reaction mass might make it an acceptable option.

Re:Correction

[Urkki]

Only a few dozen million years ago "we" were small furry rodents.

Now I have to nitpick. According to Wikipedia, last common ancestor of Rodentia and "us" lived about 90 million years ago, and wasn't a rodent. So, strictly speaking, "we" have never been rodents (furry or not), and 6-7 (dozen million years) is more than "a few" even if you take the last common ancestor.

Re:Correction

[Anonymous Coward]

The Great Apes are in the same Family as humans and we can't have a meaningful conversation with them.

Depends on how you define that. We know a bit of the vocalized language of some apes, but one problem here is that within one species there is no single, unified language.
It's the same with humans: I can't have a meaningful conversation with a Chinese person in Cantonese (and have little doubt I ever will). Even two random Chinese likely don't understand each other, since there are so many dialects.
But despite this, we have successfully communicated with apes that were reared from infancy. They seem to understand our spoken language to some degree, and talk back using sign language or a lexigram board.
Some may not call that a real conversation, but their handlers and I would disagree.

What if they are silicone based and live for thousands of years.

I for one welcome our long lived rubbery overlords.

Re:Correction

[Immerman]

Now that could be a challenge - you would need a minimum of 100,000 years just to cross it, probably closer to a million if traveling at only a fraction of light speed and not following a straight path through the intensely radioactive galactic core. But yeah, I suppose if you had a fleet of rogue planets looping through the galaxy at a substantial fraction of light speed with people breeding as fast as possible and getting off at every star they passed near, you could at least get a decent start.

If on the other hand you assume a few colony ships per century launched from each established colony, and maybe a century for a new colony to get well enough established to start sending out it's own colonists, then things slow down dramatically.

I suppose it would come down to what you meant by "the whole galaxy" - if you're only going to colonize worlds that are easily terraformable (or which w can easily be bioformed to endure) there may only be a few million to reach, if that. On the other hand if you're attempting it in only a few million years you're obviously capable of massive feats of engineering and have mastered the art of artificial ecosystems, so why not colonize all 200 billion stars, or at least the ones that won't explode before you finish?

Re:Correction

[Triklyn]

speeding up and slowing down. i seem to remember reading somewhere that slowing down from fractions of light speed are pretty hazardous to the target.

energy consumption on global scales isn't terribly viable... in general.

fusion reactors aren't even a glimmer yet. think they're trying to go for controlled fusion reaction still, and that's getting stonewalled by congressional funding.

i'll change my mind somewhat when we get a little further along to "limitless energy" :)

Re:Correction

[TapeCutter]

How so? What did it accomplish or change?

There's more than a touch of irony in military project that reached the ultimate high ground only to show us that the world domination game was not worth playing.

But I guess you had to be there to really grasp the significance of Apollo's role in the cold war. Personally I think the 1968 "earthrise" photo from apollo 8 was the most significant contribution, it's often credited with igniting the environmental movement (along with the book "Silent Spring").

The notion of the "pale blue dot" (google it) came out of that photo and exploded in our cultural consciousness several years before Carl Sagan gave it an eloquent voice. The Earthrise photo made it very clear in a lot of people's minds that there is nowhere else to go in the foreseeable future. It was clear that mankind had run out of territory to conquer on Earth and it asked the question at the height of the Vietnam war - why are we still squabbling over the spoils?

Earthrise and the PBDot are now popular cultural icons, they say something to us in the same way a red cross says something to a soldier on a battlefield.

Re:Correction

[timeOday]

With all the subsequent advances in unmanned space exploration, it is stunning to be reminded that these images first came from a manned mission. It has been decades since robots couldn't be sent to places that people cannot go. Mars feels like old hat.

Re:Correction

[Immerman]

> i seem to remember reading somewhere that slowing down from fractions of light speed are pretty hazardous to the target.

Hmm, well I suppose if you were under hard acceleration it probably wouldn't be healthy for anything caught in the exhaust at close range, and depending on just how fast your were going and how hard you were accelerating the deceleration would be worse as the exhaust density builds up in front of you. Still, it's a problem easily mitigated simply by keeping your thrusters pointed well away from the target once you get close - either aim to pass it at a safe distance, or slow down well in advance, when your exhaust still has plenty of time to dissipate to a safe density.

We could argue about how close we are to achieving controlled fusion, though certainly the mainstream research has been almost completely stalled for decades, and we it doesn't matter how close we are so long as we're dragging our feet pursuing it. On the other hand some of the more fringe efforts are starting to sound very promising - for example it seems EMC2 is finally out from under the Navy publishing embargo, and their results are looking extremely positive, with one of the few remaining major untested aspects to the theory having been tentatively confirmed. Of course it remains to be seen whether they can muster the money they need to build their commercial scale experimental reactor for the next phase of testing, but $30M is a paltry amount in the world of fusion, and if their efficiency continues scale as predicted they should be able to harness the "holy grail" of controlled P-B11 fusion. And they're not even using superconductors yet.

Re:Correction

[Evtim]

I always viewed it this way: IF there is a significant number of intelligent life forms out there, then more likely than not we are "common", i.e. likely to be "in the middle of the distribution". Therefore I am a [skeptical] carbon jingoist. Also, it seems that intelligence requires certain level of complexity of the physical carrier and not many chemical elements can give rise to vast numbers of complex compounds - the mighty carbon beats them all. Due to historical reasons in my language we call the carbon "vaeglerod" which means "giving birth to coal". I always thought it should be called "zivorod" , i.e. "giving birth to life"...

Re:Correction

[drinkypoo]

The same as when people say "but why aren't we searching for life which is unlike us", the answer becomes "because we don't know how". There's no basis on which to conclude anything other than "well, we couldn't live there".

The answer is we are. It's called SETI. Whether it's a useful means of carrying out that search is another question.

Re:Correction

[drinkypoo]

And, if we know there's like here, and then confirm there's life elsewhere ... given the size of the universe, you would more or less have to conclude that life is pretty widespread.

Would you? You really wouldn't until you found life far away, unless you found a way to conclusively rule out panspermia.

Re:Correction

[butalearner]

Pessimist. If we develop interstellar travel, even at small fractions of light speed, remain expansionistic, and avoid completely eradicating ourselves or transcending as a species we could colonize the whole friggin galaxy in only a few billion years.

Or maybe you meant "we" in a personal sense in which case yeah, barring the surprise development of feasible near-instantaneous (in ship-time of course) travel, we have absolutely no hope of visiting more than the planets in our own system and maybe those of one other star.

Pessimist. I plan to live forever as a brain in a small vat of artificial cerebrospinal fluid connected by electrodes to the controls of a tiny interstellar space ship.

Re:Correction

[Immerman]

Well, at least you didn't say as an uploaded mind, so it will still be at least partially you (how much of "you" is a product of biofeedback, hormonal, the extended brain (aka spinal cord), and secondary brain in your intestines? Kinda hard to tell until somebody makes the leap)

Achieving even single-organ immortality will still be a challenge though - are you sure you wouldn't rather survive as a liver in a jar? At least then you'd have impressive natural regeneration abilities to work with...

Re:Correction

[RockDoctor]

Hmm, well I suppose if you were under hard acceleration it probably wouldn't be healthy for anything caught in the exhaust at close range,

In some SF universes that is codified as a "law" of warfare. e.g. "The Kzinti Lesson : a reaction drive is a weapon in proportion to it's efficiency as a drive."

Re:Correction

[RockDoctor]

even at small fractions of light speed, remain expansionistic, and avoid completely eradicating ourselves or transcending as a species we could colonize the whole friggin galaxy in only a few billion years.

Billion? A few tens of million years.

The galaxy is about 100,000 LY across. If we can get to 1% of c, then moving out to cover the galaxy would take (order of) 10 million years transit time. Since you're using generation ships, then while you're in flight you can be preparing a colonisation ship in the centuries between stellar encounters and drop the settlers off (and along with them, your political dissidents, mutants and space-sick passengers and other problems) ; if they think the star is settleable (does it have asteroids ; never mind the planets for the next x generations) then they stop, otherwise they do some quick (decades) mining for consumables and then depart to catch up with the mother ship.

I'd guess that "we" could colonise the galaxy in 100 Ma. Of course, by then, the species would certainly have changed, and probably fragmented into significantly different species. Certainly cultures would have changed drastically.

But it's all SF for the next number of generations.

Re:Correction

[RockDoctor]

The laws of physics (and chemistry) are the same pretty much everywhere

Where, precisely, do we know that the laws of physics are different from those we see here? "pretty much everywhere" implies that there is somewhere that isn't included. Where is that?

Re:Correction

[K. S. Kyosuke]

For example, in the immediate vicinity of a magnetar, the strong magnetic fields would deform electron orbitals to the extent that life chemistry with complex molecules simply might not work.

Re:Correction

[Immerman]

I'll admit I was assuming colonizing the whole galaxy wasn't a specific goal but just a side effect of us doing what we've always done. In which case it might take many thousands of years for a small colony of misfits who've integrated generations of interstellar near-zero population growth into their culture to grow to fill a star system to the point that their own misfits start to feel the need to spend generations in interstellar space to get away. After all without FTL there's not many other reasons to cross the gulf between stars.

Of course, I suppose after generations on a world-ship it's quite possible that not everyone would want to settle down, so it could well be a matter of offloading the colonists and hanging around just long enough to get them well established and resupply the world-ship before setting out for the next interesting star. But that scenario doesn't benefit from an exponential growth curve, and we've got hundreds of billions of stars to fill . Still, I suppose a group of those could well establish seed colonies sparsely scattered throughout the galaxy in only a few hundred million years, each of which could then become the hub of a new exponentially growing sphere of colonies.

So then we run into Fermi's paradox - can we really be the first species to arise in this galaxy that has such inclinations?

Re:Correction

[RockDoctor]

Those strong magnetic fields would, indeed, change the energies of electron orbitals (indeed, of proton orbitals inside complex nuclei too), but they'd do so in accord with the laws of physics. That would (probably ; IANA quantum mechanical chemist) change the laws of chemistry to be different to those that apply in lower magnetic fields (and lower field gradients too). However the underlying laws of physics will still be the same.

There's a very definite hierarchy of precision and strength of lawfulness in the sciences. If we accept economics as being a science (the dismal science), then it's "laws" are much looser than the laws of biology. (I was reading a paper last night on the laws of social evolution of non-breeding behaviour, couched in terms of probability of various outcomes, and the consequent effects on probably descendent count for each member of the population ; those laws were couched very much in economic terms, of calculating probabilities.) The laws of biology are much stricter ; egg plus egg does not make a fertilized egg ; 23 chromosomes plus 24 chromosomes makes for a pretty fucked-up organism, if it's viable at all ; oxygen metabolic enzymes plus sulphide (or hydrosulphide) ion makes for a broken or non-functional enzyme molecule. The laws of chemistry underlie the laws of biology and are considerably stricter ; in aqueous solution, silver ions plus chloride ions precipitates silver chloride if the solubility product of AgCl is exceeded (assuming no thiosulphate ion in solution) ; argon reacts with fewer elements than xenon, and forms less stable compounds ; silver chloride has the sodium chloride structure at NTP. The laws of chemistry themselves are founded on the laws of physics - those precipitations and crystal structures are basically the result of electrostatic interactions (as are the more subtle interactions of quantum mechanics in forming covalent bonds) ; when people talk about "unknown new laws of physics that will give us FTL travel, I invite them to jump out of a tall building and try to argue for an exemption from the laws of gravity.

In your example, the changes to the emergent laws of chemistry result from adherence to the more fundamental laws of physics.

If you can drag up a few string theorists, I can bring some mathematical philosophers ; we can throw them into a pit and let them fight it out to see if physics or maths is more fundamental to the universe. I'm not a great fan of either marshmallows, or popcorn, but I can bring a barbie and some great venison burgers.

Re:Correction

[RockDoctor]

Of course, I suppose after generations on a world-ship it's quite possible that not everyone would want to settle down.

I'd say that's a racing certainty. It's not a trope I've seen exercised much in SF (a notable exception being "Building Harlequin's Moon" by Larry Niven and Brenda Cooper. The necessity for a mutli-generational approach would tend to cramp things like character development (BHM spans a period IIRC of some 60,000 years, as the colony ship has to lay over to carry out repairs, and in the process need to, erm, build a moon. In orbit around "Harlequin." (Niven is Old School SF.)

There are interesting things to think about in such a situation and a mission. Including, particularly, how do you man a mission that is going to be profoundly multigenerational. How do you know you're going to be able to motivate the 79th generation after launch?

Re:Correction

[Immerman]

I would think you don't worry about motivating the 79th generation, any more than you do on Earth - unless you've got an automated system installing neural clamps at birth you'll have absolutely, positively lost virtually all influence on the culture long before. What you do is put them on a ship big enough that they don't go insane and point it at a distant star around which you've confirmed there's a hospitable panet (gravitational lens telescopes are your friend). Then, assuming nothing unexpected happens, your descendents will eventually reach the star and have to at least stop to resupply, at which point they can make their own decisions about what to do. Why would you want to chain your descendents to your own limited vision? Assuming 20-30 years per generation you're talking ~2000 years in the future. Think about where we were 2000 years ago - would you be happy if our lives today were bound to the vision of some ancient Roman emperor?

Re:Correction

[RockDoctor]

Why are you expecting them to stop? That's a huge waste of fuel.

Like I said, put them into a ship with big enough storage to drop off a colony-forming ship every 10 generations - let them do the deceleration, mine your consumables, and re-supply the mothership. If that's happening every 10-20 generations, then you've got a release valve for your society (something that we don't have at the moment, but designing a society with release valves is one of the influences you can have across the millennia). And if (again, racing certainty) some of your would-be colonists get freaked by leaving the mothership behind, then the colonists have a release valve as they're establishing their society since there will be a re-supply mission accelerating back to the mothership next generation.

you've confirmed there's a hospitable panet (gravitational lens telescopes are your friend)

Short of manipulating a large (planetary mass?) lump of neutronium (which I'm not sure can exist), we don't have even a vague direction for such an object. And if we had to do that, we might well find it easier to go there (or send robots and relay stations) than to build such a telescope.

would you be happy if our lives today were bound to the vision of some ancient Roman emperor?

Some people seem to want to bind themselves to the pronouncements of some Roman carpenter, of whose existence we're by no means confident and whose diktats are based another half-millennium further back when (putative) his ancestors were slaves. At least we're pretty confident in the existence of the Roman emperors, even if some of them were as mad as a box of badgers. (I'm actually planning a walk along Hadrian's Wall - after that, I can securely attest to the existence of a Wall, with at least legion-marks referring to Hadrian ; after which, disbelieving in his existence would be perverse. In a generation ship, the existence of the ship, and it's constructors, would be hard to ignore.)

Like I said, that's why you build your society with (ir-)regular break points. Whether you have the ship travelling on a loop, or just driving straight(-ish) on for the horizon ... well that might be something that you re-assess every millennium or so. It would be another break point. Maybe you build into the design so that every 10 dropped-off colony ships, you can fission your mother ship into two and then continue to grow each on their chosen routes. Each generation would still need to be making choices, but equally each generation would be subject to constraints (as we are) which were imposed on us by ancestors only a (relatively) small number of generations ago. If you're an American, then almost certainly one of your ancestors chose to travel half-way around the world less than ten generations ago ; if you're not an American, then almost certainly several of your ancestors chose to NOT travel half-way around the world less than ten generations ago. How do you feel about those choices, whichever way they went?

Assuming 20-30 years per generation

Big assumption. The pressure to use medical developments and technologies to extend life is strong. On the assumption that the mammal body plan can't be pushed beyond 200 years, why would you go around doing momentous things like breeding before your 80s? Remember that for most of human history it was reasonably common to co-exist with your grandchildren, but seeing great-grandchildren was pretty rare. I'm trying to think of a mammal (or bird ; I don't know about reptiles or elasmobranchs at all, to cover the disparity of the vertebrates) that does routinely see it's great-grand offspring. If you wanted to change the generation ship people into a new species, that might be one of the most effective ways to do it - change life spans.

Re:Correction

[Immerman]

Actually such a telescope is relatively easy to build, just a little difficult to get in to position and slow to retarget. But a planetary mass isn't nearly sufficient to examine planetary surfaces over interstellar distances, you need a stellar mass to really see the effect shine. Put the Hubble out at 600+AU and look back at our sun (hidden behind an occluding disc of course) and you've got your gravitational lens. For a world ship, which I'm assuming spends most of it's time coasting, you could easily have a super-Hubble coasting alongside searching for candidates, and before you even deploy your colonization/resupply crews you send out a few additional telescopes to use the current target star as a lens to closely examine the candidates you've identified further along your (approximate) current trajectory. As an added bonus you can leave one of the telescopes behind, focused along your new trajectory, to maintain tight-beam communications between the colony and your ship (and eventually the next colony). Lag would get to be enormous obviously, but you would have a way for your colonies and ships to keep in touch over interstellar distances with minimal transmission power requirements, especially if you deployed a second G-scope at each star looking back at the previous colony - then you could communicate at a veritable whisper, and only somebody directly along the transmission line would have any hope of hearing you.

>Some people seem to want to bind themselves to the pronouncements of some Roman carpenter
Except that, despite their claims, very few actually want to do any such thing - mostly they largely ignore even what the literature claims for his actual lessons, instead cherry-picking incidental comments to construct a wall of rules that just happen to ban everything they don't want other people to do.

As for designing your society with break points - sure, you can try to do so - point the ship at a distant star and you've "scheduled" a break point at arrival. But nothing stops the travelers from deciding interstellar travel sucks and simply cannibalizing the world ship to build the colony. Or the iron-fisted dictatorship who's risen to power in the interm deciding that public executions make for a much more useful "release valve" and avoiding stars altogether except for sending out robotic resupply missions.

Re:Correction

[Immerman]

Should have added - that carpenter gets special moral authority from his claimed relation to God, and there's only a handful of individuals in history who've been credited with such significance. You - you're just the dreamer that decided to launch a ship to a distant star. Or are you hoping to grow in legend until your distant descendents come to worship you as well?

Re:Correction

[RockDoctor]

You've plotted three chapters for the compendium "Generation Ship Tales", examining the fates of the generation ships sent out by Earth in the 3000s.

ha, ha, but serious. There's a sea of ideas out there for SF authors to mine, but they don't seem terribly inclined to dip into that particular pond. targeted anthologies ("Dangerous Visions", the Berserker universe) have a decent track record for getting people to play with an idea.

Re:Correction

[RockDoctor]

that carpenter gets special moral authority from his claimed relation to God, and there's only a handful of individuals in history who've been credited with such significance.

There's no shortage of people claiming such a relationship with the FSM. On my friend's locked hospital ward the last time he had one of his episodes, there were 4 claimants.

The number who have actually had such a relationship remains the same as the number of gods - zero.

Or are you hoping to grow in legend until your distant descendents come to worship you as well?

Well, It's not impossible for my legend to grow. Does that mean I'd need to log into FaceSpace and MyBook more than every few months? But it's absolutely impossible for my descendants to worship me, absent one of (1) The Plastic Hippy having had a 15 month pregnancy after we broke up, or (2) someone microsurgically repairs my vasa deferens then anally rapes my corpse with a cattle prod to get a semen sample (the latter has happened, and Diane Blood seems proud to have raped her husband's corpse so. I would hope the necessary repair work would suggest to the courts my strong desire to not have descendants ; since it would require the work of lawyers, I'm not going to bet on it never happening.)

Re:Correction

[Immerman]

I reserve my opinion on the number of gods until I see evidence for or against their existence. Certainly many have possessed metaphorical existence, with their priests wielding massive sociological powers in their name, and I have seen enough first-hand evidence of intentional phenomena that stretch the limits of plausibility that I'm willing to entertain the possibility that it might be possible that at least some manner of beings capable of discretely playing the part exist. (Ever read American Gods by Neil Gaiman? A rather amusing take on the possibility that gods exist, and were created by man) Personally though I lean more towards the Tao - I've seen plenty of direct evidence for that, and am still not sure whether it's an actual "thing" or just a very apt metaphorical construct to describe the synergies in a chaotic system. Or even whether there's any meaningful distinction between the two positions.

Swampland!

[TechyImmigrant]

This makes sense. The University of East Anglia exists in swampland that is slowly sinking while the sea is slowly rising. It's halfway to ocean already.

Such like won't have technology

[sandbagger]

Why?

No flint tools or fire. Ergo, when we get there we can eat them!

Re:Meaning of LIFE!?!?

[ColdWetDog]

Maybe yes, maybe no.

We know that life has started out in an anaerobic environment with water present. Everything else is up for grabs. So if you're looking for life-as-we-know-it, it makes sense to go with the conditions we already know works.

TF Headline is, of course, hyperbolic. Alien life doesn't necessarily require conditions similar to earth. But that's were the money is. If you have limit the types of planet systems you will spend the time and money to look carefully at, you just might go with what has worked.

Extremophile

[khasim]

Extremophile

I'm thinking more along the lines of "Life that will use radio signals (or similar) to communicate in such a way that we have a chance of detecting them without either of us leaving our solar systems".

But that's a bit wordy.

Re:Extremophile

[i kan reed]

There's a couple things here:

1. Extremophiles evolved progressively to more difficult ecosystems. They came from organisms that could manage in chemically unreactive of mostly water/salt water. It's unlikely the precursors to life, like prions or unbound mRNA chains would've "made it" in arsenic lakes or boiling lakes. But some prokaryotes could manage in environments with a little arsenic, and evolution could work its magic.

Like the creationists say, getting something as complex and robust as a modern organism "randomly" would be a bit like a tornado blowing through a junk yard and assembling a car.

2. The utility of radio waves for communication wouldn't hinge much on the physic form of an organism, just something much like sapience.

Re:Extremophile

[itzly]

2. The utility of radio waves for communication wouldn't hinge much on the physic form of an organism, just something much like sapience.

Radio waves don't reach very far before they are drowned out by natural sources of radiation. Beyond one light year, you already need powerful radio sources, combined with large antennas to detect them. And there's only a short time window. It took earth billions of years before we started emitting radio waves, and already we're reaching the end of the window with the increased use of wide spectrum digital transmissions that are much harder to detect from a distance.

Re:Extremophile

[smaddox]

Also, efficient data transmission is indistinguishable from noise if you don't know the protocol.

It's worth noting, however, that the SETI program only ever really looked for explicit beacons from alien civilizations, hence why they picked the radio frequency of positronium spin flip (and other similar frequencies from fundamental physics).

Not on Arrakis

[Squidlips]

That proves it is wrong... Actually Mars probably had a northern ocean but we do not know if ever supported life. I suspect that Earth is in a delicate balancing act. Not too much and not too little water. BTW, if you averaged all the elevations on earth, none of it would be above the level of the ocean. If plate tectonics stops, as it probably will in a billion or so years, then all the continents will be eroded to nothing and Earth will be a water world.

Re:Not on Arrakis

[TechyImmigrant]

> BTW, if you averaged all the elevations on earth, none of it would be above the level of the ocean.

This would be true of any planet with any amount of surface water.
Given a perfect sphere, the water is just going to spread out and cover it.

You can't go around leveling the land without impacting the water level. They are linked.

Re:Not on Arrakis

[Your.Master]

This would be true of any planet with any amount of surface water.

This statement isn't true. The rest of your statements are true.

Consider a perfectly spherical planet with no surface water, but with an underground water supply not too far below the surface (eg. as Europa is hypothesized to be).

Now make it less smooth, eg. slam it with meteors such that there's no net loss in matter (possibly a slight net gain), but it's no longer perfectly smooth.

Now you have surface water on a planet with an average elevation higher than the water level.

Basically, any planet with surface water (or methane or whatever) and surface not-water is going to have an average elevation of water and an average elevation of not-water and they are likely going to be similar relative to the size of the planet as a whole, but there's no general statement you can make about which one is higher (there may be a probabilistic statement).

Re:Not on Arrakis

[Squidlips]

ACK, you are right. What I meant to say is that the total volume of land above water is a lot less than the total volume of seawater. Earth is a water world. If it was not for plate tectonics then there would be no land masses except possibly some hotspot volcanos (i.e. like Mars) poking up to the surface, but no continents.

Re:Not on Arrakis

[Immerman]

Actually if I remember my Dune correctly water was once plentiful on Arrakis, but was locked away deep underground by the larval sand trout in order to provide a more hospitable environment for their adult form, the sand worms.

Also, if plate tectonics stops that means our planet's core has cooled to the point where it can no longer provide a strong magnetosphere, at which point the solar wind will begin stripping away our atmosphere, boiling away the oceans in the process as the air pressure drops, and leaving erosion to be a process fueled primarily my meteorite impacts. Much as is believed to have happened to Mars some time in the last few tens of millions of years.

Re:Not on Arrakis

[TechyImmigrant]

That's why I said surface water.

My statements wouldn't apply to a realistic scenario with underground water.

Re:Not on Arrakis

[TechyImmigrant]

Yup.

From what I've read, it seems that plate tectonics have something to do with bringing water to the surface, so it might be a more co-dependent relationship between P.T., oceans and continents.

Re:Not on Arrakis

[dryeo]

Venus is a counter argument to the idea that without plate tectonics and/or a strong magnetosphere the atmosphere would be stripped away. At that some theorize it is the plate tectonics (and life) that remove carbon allowing our atmosphere to be as thin as it is.

Re:Not on Arrakis

[Immerman]

Fair point. In fact while confirming it I came across the fact that Earth is actually losing atmosphere to space faster than Venus - something that appears to rather harshly conflict with our theories on the subject.

Re:Not on Arrakis

[dryeo]

It's complex. Note that Venus has lost most of its hydrogen and like the Earth, its helium. For the Earth, much of the atmosphere losses is probably hydrogen liberated by photo-disassociation of water which is where much of our hydrogen is tied up. Heavier molecules such as CO2 get held by gravity.
One future scenario for the Earth is to become Venus like, perhaps as soon as a billion years. The Sun gets hotter over its lifetime due to increasing percentage of helium from fusion increasing density, eventually the oceans boil which means lots of water vapor causing a runaway greenhouse effect. Limestone and other carbon sinks liberate their carbon due to the heat which combines with the oxygen which is released by the water vapor being photo-disassociated causing lots of CO2 and adding to the greenhouse effect. Plate tectonics stop due to no water to act as lubricant. Internal heat becomes more equal and convection stops around the core which shuts down the magneto. Eventually the interior heat melts the crust, lots of volcanism which releases more carbon and we're now Venus like.
One possible way that Venus became the way it is now is the above. Possibly life existed before the run away greenhouse effect kicked in and it is also possible the magneto starts up periodically on Venus after a resurfacing event cools down the upper mantle and convention restarts. Be interesting to know more about the interior of Venus.
There's also Titan, closer to the Moon in size and slightly higher atmosphere pressure (mostly nitrogen) then Earth, lots of variation out there and much we don't know.

Garbage in, garbage out

[zephvark]

Not to put too fine a point on it, right? Look, you need to base a model on something before you can even guess it might possibly mean something. World of Warcraft is a lovely model, but it doesn't predict the nature of life on other planets, it's just a game. This is not remotely news. Get back to us when it's been demonstrated to reliably predict the presence of life.

Re:This is silly...

[Triklyn]

H2O is a pretty awesome and creepy molecule. and has some pretty important properties that make advanced chemistry easier.

and with that insult

[QAChaos]

the last dolphin says "so long and thanks for all the fish"

Re:Not necessarily water oceans

[Your.Master]

What?

First of all, there are more than three phases of matter. A molecule in plasma state, despite being far apart from its neighbours like gas, interacts easily with them like liquids.

Second, "too far apart" is not well-defined or proven.

Third, "molecules aren't moving" isn't true of a solid object, nor have you shown why that's necessary for life.

The life forms we are most familiar with happen to include aspects of all three phases (no plasma aspects in any life form I know of). The artificial things we have created that exhibit some life-like characteristics, even though we all agree they aren't life (at least not yet), tend to be solids, like silicon chips -- electricity provides the transport mechanism through the solids.

Oh, *that* UEA!

[tgeller]

To me, UEA = Universala Esperanto-Asocia, the organization tasked with assisting speakers of the language Esperanto.

I thought maybe they'd branched out in a totally unexpected way.

Re:Meaning of LIFE!?!?

[Immerman]

And how would you recommend we look for life of a kind we have no understanding of? We're still trying to figure out how to detect life-much-as-we-know-it if it's not jumping up and down and screaming (metaphorically of course). An example of a much easier problem: Suppose I know with absolute certainty that there's a specific thing in the room with you. Given only that much information, do you suppose you can identify it? Now identify the other specific thing that I suspect is also in the room. That's the life-as-we-don't-know-it challenge.

Re:Earth is unique, but not a snowflake

[Immerman]

Actually, there's some argument that tidal flats were important in the evolution of early life, as were the amplified plate tectonics (life probably evolved around underwater volcanic vents. Not to mention the fact that having a large moon kneading the planet has dramatically slowed the cooling of the core, maintaining a strong magnetic field for far longer than would otherwise have been possible. Which in turn allows an atmosphere to be retained. Mars has plenty of gravity to retain an atmosphere, and it could conceivably have hosted an Earthlike ecosystem as recently as 10 million years ago. But then it's core cooled to far, shutting down its magnetic dynamo and allowing the solar wind to strip away whatever atmosphere it had, boiling away any substantial surface water in the process and carrying that away as well (the boiling point falls with decreased air pressure).

Also, just FYI, fusion only happens naturally in stars - hydrogen and oxygen react chemically to form water in a completely unrelated process. And incidentally free oxygen is reactive enough that it's presence is a likely indicator of life - something needs to produce it faster than it can get re-bound into oxides, but it's definitely not necessary for life-as-we-know-it to exist: Life on Earth all evolved from anaerobic ancestors, and most of it was eradicated by the toxic oxygen released by the first photosynthesizing bacteria. To this day most life on the planet is indifferent to oxygen, it's only a miniscule fraction of those forms colonizing the outermost surface of that has evolved to harness the toxic substance for fuel.

Limited Imagination

[14erCleaner]

This result (which basically says that any planet with life has to look like ours) reminds me of an article I read long, long ago speculating on what ETs would look like. The author basically concluded that they'd have to look exactly like us, i.e. two arms, two legs, head on top with two eyes and a mouth and a nose, etc., and he had arguments for why each of these things was necessary. Of course, almost none of the thousands of other species on Earth look exactly like us, but that didn't faze him in the least in his application of logic...

Why does everyone always assume that life requires water, anyway? Couldn't there be a planet out there infested with silicon-based life forms who live at 300 degrees Celsius, or whatever?

Re:Limited Imagination

[smaddox]

Because complex chemistry is a prerequisite for life. There's a reason organic chemistry (carbon-based chemistry) is it's own topic--it's extremely complex.

Re:Limited Imagination

[drinkypoo]

Of course, almost none of the thousands of other species on Earth look exactly like us,

Exactly? Come back here with those goalposts. Creatures here have eyes above nostrils above mouth for a reason; likewise, they have head above body (at least in some positions) for a reason. The mouth is at one end, the ass at the other. If it were advantageous to have these features somewhere else, they might well. For anything which meets our definition of life, it's reasonable to imagine that they would take on a similar form.

Re:Not necessarily water oceans

[Immerman]

Actually, the problem with a gaseous environment is not that the molecules are too far apart - in fact you get a (very roughly) comparable frequency of collisions, and they're at higher energies which make reactions more likely. The problem is that as larger molecules form they tend to precipitate out of solution, and in a gas there is insufficient buoyancy to keep them mobile once they've done so. On Earth life likely evolved within the primordial open-faced sandwich on the bottom of tidal pools, borrowing mobility from the surrounding water and structure from the solid substrate. Get rid of either and things become much more difficult, though there's no reason to believe it would be impossible. Get rid of both (such as in the atmosphere of a gas giant where chemistry becomes radically altered at the enormous pressures around the quasi-solid core) and you're in completely unknown territory.

It's also worth mentioning that gas-versus-liquid has little to do with distance between molecules except at a given pressure, the phase is determined by the nature of the weak intermolecular bonds. The gas deep within a gas giant could be far denser than water, but the immense pressure and temperature maintain it in a gaseous state, smoothly transitioning to liquid as you go deeper. Or perhaps not - high-pressure chemistry is still a very young field and we keep discovering surprising things.

Re:From the makers of "Global warming" comes...

[xevioso]

And how do you know it is bullshit? Do you have better evidence, or are you making it up? Pulling it out of your bottom? Making up "bullshit", as it were?

Re:From the makers of "Global warming" comes...

[Cryacin]

Will somebody please think of the extremophiles?

Looking for life

[PeterM from Berkeley]

It'd help a lot if the life we're looking for feels like broadcasting really, really powerful modulated EM signals, directed mostly at likely habitats for other life (namely, us.)

--PM

Re:Not necessarily water oceans

[dryeo]

Some crystals also have some of the qualities of life

Neil DeGrasse Tyson

[The Evil Atheist]

As Neil Degrasse Tyson notes, the life we do know is primarily made of, in order of proportions - hydrogen, oxygen, carbon, nitrogen, other. Other than helium, the order matches exactly the proportions of "normal" matter in the universe. It's not a stretch to look for life made up of the most common elements in the universe.

Re:Meaning of LIFE!?!?

[Eunuchswear]

LIFE may originate on some planet where Methane, Hexaine or Helium is the local liquid, or molten Lead, Carbon or Iron, or, or, or...

Chemistry.

Carbon is probably where it's at in terms of a backbone that allows for enough complexity, and that puts some limits on temperature and other parameters.