by Matthew Cobb
Either we are the only form of life in the universe (and by ‘we’ I mean the monophyletic group of organisms that live on Earth), or we aren’t. And either way, that is probably the most amazing thing we could ever know. Because we don’t actually *know* the answer to the question ‘Is there life elsewhere in the Universe?’, we can all have an opinion.
So, at the risk of encouraging loons of all varieties to post here, what’s your answer to the question, and above all why?
FWIW, my assumption is that there is life elsewhere, simply because the Universe is a big place that’s been around for a long time and is full of the stuff we needed to get going (amino acids, energy, water) – never mind the possibility that life could exist using other bits and pieces. Whether we will ever come across that life is another matter. I would be overjoyed if there were signs of life having once existed on Mars. Although I’m not sure why I’d feel overjoyed.
Oh, and if you want a great description of how we’re all related, this fantastic website, which I saw on @carlzimmer’s Twitter feed, is all you need.
My opinion is yes, there is life elsewhere in the Universe and I base that on two things:
1. Probabilities. With 100’s of billions of galaxies having billions of stars each, and Kepler proving once and for all that many stars have orbiting planets, it would seem even a low level of probability would suggest that more than one, us, has the right conditions to support life.
2. We are stardust. All the stuff that comprises life on earth came from the Universe itself. So if the Earth can contain all the heavy elements and chemical goodies that allowed life to begin, why wouldn’t other rocky planets?
The sheer numbers suggest that we should be stunned if there isn’t life out there. But will we be able to prove it? Not in my lifetime.
I wouldn’t be so sure daveau. I think it is possible to get the spectra of planets atmospheres as they pass in front of stars. (don’t take my word for it, I’m no expert)
If this is the case, then it should be possible to discover the presence of complex organic compounds strongly suggestive of life.
We’re unlikely to see organic compounds in the spectra of other worlds. Methane is not a good indicator since there are non-biological means of formation (otherwise our gas giant planets would not exist). The organic compounds which we can detect in our atmosphere are largely there due to human activity. Some marine organisms produce methyl bromide, but given the fact that most organisms on earth do not produce methyl bromide, what are the chances that life on other planets would?
What about free oxygen? Seems to me that would be easy to detect but hard to explain without invoking life.
Or to put it another way, you don’t need to detect organic compounds directly. Any indication that a planet’s atmosphere is out of chemical equilibrium would imply some active process that keeps it that way.
SETI could potentially find the smoking gun today, for all we know. Whether or not one thinks that’s likely is another matter, but “not in my lifetime” seems too firm a position to take, IMO.
Depends on how old one is. A bit ambiguous, I grant you.
“but “not in my lifetime” seems too firm a position to take, IMO.”
But he’s probably right.
I doubt SETI would be a success; to receive and recognize an unambiguous signal from any but the closest stars would require a transmitter with phenomenal output power – whether radio or light.
But a SETI-sending civilization wouldn’t necessarily need to generate signals of that power. The galaxy is full of naturally-occurring radio sources, and technological species like us are already looking at them. All you’d need to do to send a message is figure out a way to modulate an artificial signal onto one of those naturally-occurring sources.
For instance, you might set up a giant resonator or Fresnel lens or something near a pulsar to deflect or delay by some tiny amount a small portion of the radio energy passing through it. This might appear to a remote observer as an anomalous echo or distortion of the expected pulse shape — an anomaly they would want to get to the bottom of. If you can vary this anomaly from pulse to pulse in a systematic way, you can send a message.
Wouldn’t a Fresnel lens focus on a very small area of space? How would that work for general broadcast?
The trouble with SETI is that we’re looking for these signals at the bottom of a gravity well bathed in air and radiation from our nearby star. Seems almost self-defeating.
As for the question of whether life exists elsewhere, I’d say it’s quite likely, carbon being so reactive. Anything more complex than eukaryotic life might be a bit rarer though.
I’m with you. I think it’s quite likely that we’re not alone, though the distances involved (if light is absolutely, no doubt about it, never going to change, the universal speed limit) are so great that we might never meet any alien life forms.
The Kepler mission has been finding “nearby” exoplanets hand-over-fist though, so it’s not inconceivable that we find a planet similar enough to Earth to at least entertain the idea that it might harbor life.
Assuming that by ‘the only form of life in the universe’ you mean either such that can communicate with one another and also develop the technology to escape their own planet temporarily, or your mean all DNA-based species. Either way, color me agnostic.
Sure, it’s possible, but what difference does it make? To get a human to another planet that might have intelligent life would exceed the lifetime of the human in the capsule, and well before that food supplies would run out. And to even get to that point, the funds are insufficient. Oh, but, oh, but, some will say. But really, the practical chances are infinitesimal. There are other things far more appealing to contemplate.
With regards to getting a human to another planet that might harbor life, you’re thinking in terms of today’s technology and today’s “human”… I can picture people poo-pooing early Earthbound explorers in the same way, a thousand years ago.
Our descendents a hundred, two hundred, five hundred years hence may achieve all sorts of relevant advancements that enable them to travel to the stars.
“What difference does it make?” strikes me as profoundly unimaginative. Maybe what you mean is “what difference does it make to me?” What is “far more appealing to contemplate” is subjective.
Profound imagination begat Scientology and a lot of other things we could do without.
Tackling abiogenic origins seems far more tractable by comparison, requiring profound insight in addition to deep understanding of chemistry.
Profound imagination + ignorance begat Scientology. Imagination + knowledge begat the internet.
Imagine how exciting it would be to compare notes on theoretical physics, or mathematics, or biology, with an intelligent alien race that arrived at their sciences through a completely different set of historical events and sensory organs! There can be no doubt that our own science has been shaped by historical accidents and our own peculiarly limited range of sensory abilities. Looking at another world’s science could give us mind-boggling insights into reality.
“Looking at another world’s science could give us mind-boggling insights into reality.”
Whether or not there is alien life, this is definitely true. In the unlikely event that we compare notes with an alien race roughly as advanced as our own, I suspect there will be a lot of facepalming and cephalothoraxpedipalping as we realize all the obvious-in-retrospect stuff we missed because of historical accidents, dumb luck, and the quirks of our senses and language.
Congratulations moochava. Your comment is the only link or Great Living Omniscient Lord Google can say on the matter of “cephalothoraxpedipalping”.
I move that “cephalothoraxpedipalping” replace “facepalming” forthwith.
+1
+ 2
Love it! 😀
+3
So it is written.
Let it be done.
“cephalothoraxpedipalping” makes me think of the arachnid version of Curly Howard.
Keep in mind, there are creationists even among lifeforms very similar to us, sharing large portions of our history.
I too believe that life exists elsewhere in the universe. For the same given reason that the universe is a big place and so there’s lots of possible opening for life to have popped up.
I’d go one step further and say that whatever life there is in the universe, none of it has free will.
Alien meat robots!
You just had to say that steve!!
Well… technically I did as I was moved to do so.
This is a very popular topic for blogs and one of my favorite blogs did a really nice post on it: Where is everybody?
Taking the million-year estimate and our prior optimistic figure, that means there may be as many as 25,000 civilizations ready to communicate with us right now in the Universe. (Clarification: this is 25,000 civilizations in our galaxy, which are the only ones in the Universe we’ll be able to communicate with on sub-million-year timescales.)
But taking the pessimistic number and applying our pessimistic estimate? There’s only about a 10% chance of there being one Earth-like world, today, with a species like us on it, in the entire Universe.
It take this to mean there is a 90% chance that there is more that one Earth-like world in the entire universe?
Haha, no, it’s at most one. It is astonishing that by being mildly pessimistic, we get that there’s 90% chance that there is no life form with the technological capacity of communicating with us in the entire universe.
The Fermi question is too loosely constrained to be useful.
Here is a loophole:
There has been 3 mass extinctions since land life, bottlenecking then recapturing diversity and so constituting independent worlds. Hence 1/3 of planets with multicellulars for ~ 0.5 years have technical intelligence. Reuse for having multicellulars in the first place: ~ 1/10 of inhabited planets will have ETI.
[You need eukaryote analogs with energy plants in the form of mitochondria endosymbionts. This gives ~ 10^5 more energy for protein turnover to make more traits. Bacteria makes multicellulars, but not complex ones.]
Inhabited planets are likely a dime a dozen, see my initial comment in the thread.
Communication will not happen because of how colonization will spread.
On an exponential scale, the scale of exponentially growing technological societies, the jump to the Oort cloud is the largest after the jump to a putative moon like ours. Once you are there, you are set: comet bodies for movable habitats, volatiles for biospheres and rocket engines, fissionables for energy.
An Oort cloud migration will migrate over a galaxy on the scale of the lifetime of the universe.
– Populations will soon evolve beyond recognition, so will not communicate between habitats.
– Planets are risky and costly descents into deep gravity wells, providing you remember to look for planets in the first place or can redevelop the technology from orbit. (I bet you can’t, at least easily enough.)
No communication there either.
Seeing that such loose constraints and loophole pathways exist, the question is useless. A negative result won’t tell you anything.
“or ~ 0.5 years” – or ~ 0.5 billion years.
If I had to hazard a guess, there’s at least as much of a gap between an Oort-scale civilization and ours as there is between ours and the bronze age. I doubt I’d believe anything less than between ours and the age of sail.
Note that I’m not referring to the ability to send probes to the Oort, but to a civilization where the majority of its members live in the Oort.
I also doubt that a civilization would move out…energy is the big problem, not access to raw materials, and the sweet spot for energy density is as close as you can get to the sun without frying.
Compare, if you would, the total energy capacity of all fissionables in the Oort with insolation at Mercury’s orbit. I’ll bet you a cup of coffee that covering the sunward side of Mercury with photovoltaics (assuming they wouldn’t melt) would give you as much energy as is extractable from all the Oort’s fissionables in under a millennium.
b&
Maybe so, but there’s no rule saying you have to live on Mercury to use it. Just cover the back side of Mercury with a phased array of lasers and you can send the energy anywhere you like in the solar system.
Vernor Vinge in his Across Realtime had plants inside Mercury’s orbit for manufacturing antimatter from solar energy, which then got shipped throughout the solar system. Seems like the most sensible option to me, short of a Dyson Sphere.
In his story, the biggest downside to those working in those factories was the time lag and narrow bandwidth to the ‘Net on Earth, which again seems entirely plausible.
So long as you grant him his second-law-of-thermodynamics-violating bubbles, he even got all the physics, including energy scale and conservation, pretty much right on the money. Including interstellar travel. And I don’t begrudge him that violation, since it’s not only the one-and-only bit of unobtanium he used but, indeed, is the “curious idea” that drives the entire trilogy — without it, he wouldn’t have had a story at all.
b&
Is there life elsewhere in the Universe? Well, if it happened once it means it’s possible. If it’s possible, then it can happen more than once.
I wouldn’t be surprised if science cracks Abiogenesis soon. And finds that it’s a not-particularly esoteric process. The right combination of common chemicals, input energy, water, enough time and bang. Life. And then evolution.
I think there is a high probability that alien life exists. Intelligence life is another story. Even if a creature did develop high intelligence they might lack the necessary physical form to do much with it (think dolphins). Plus the vast distances of space essentially ensures that contact will never be made. For all practical purposes we are alone, although it would be heartening if we found life to be fairly ubiquitous in our own solar system.
But anyone who thinks aliens are visiting Earth in spaceships has an overactive imagination.
MC: I agree. I could not have said it any better than you did:
I’d be overjoyed (Mars life) for a number of reasons:
1. Science! It rules!
2. Deflation of the human-centric/earth-centric view of the universe
3. Fun new stuff to study
4. Maybe a look backwards at early life on earth?
5. Maybe discover a non-DNA replicator?
6. Check that Mars life for relatedness to us (assuming DNA life there) — might point to something like directed (or undirected) pan-spermia???
When I think about discovering life, even something as simple as a microbe on another planet within our own solar system, my first exhilarating thought is: “How does it work?”. All the other stuff would inevitably follow suit.
I’m sure the universe is teeming with life. At least, it is on planets around fourth or later generation stars like our sun.
As on Earth, most of that life is simple. And, save for rounding errors, all of it is carbon-based — yes, it’s theoretically possible with other chemistries, but nothing else comes close to carbon in terms of ubiquity and usefulness.
Complex life will be at least as weird to us as squid or termites. Probably much weirder. However, the top predators in aquatic environments will be tuna-shaped; the predominant color in plants will be a close match for the star’s peak spectral output; and so on.
There are no interstellar civilizations. Or, if there are, they’ve already built a Dyson Sphere around their star and their population explosion from exponential growth is causing them to gobble up all the rest of the stars near them as fast as they can, and their host galaxy has less than a million years before even that’s not enough.
How do I know that? Simple math. You need as much energy as our entire species consumes in an entire year just to get something the size of a regional jet to the closest star in a mere decade. Realistically, interstellar travel requires a significant fraction of a star’s power. The only way to get to the point where you can harness that kind of energy is through exponential growth…and, if whatever drives the species to grow like that is enough to get it to that size, nothing will stop it at its own star system.
And that’s why Dave is exactly right that we’ll never have a way of directly observing any of this in his, or anybody else’s lifetimes.
Cheers,
b&
I’m fascinated by the concept of a Dyson Sphere (and the similar ring designs) and I wonder how plausible such a construction would be. How strong a material would be required to make a solid sphere not only large enough to contain the Sun, but to absorb its solar winds?
How much mass would be required? Would the inner planets broken down for the purpose be enough to get it done?
I’m pretty sure you can find theoretical discussions without too much work…but you should start with a sense of perspective.
Cover one of the flyover states with off-the-shelf solar panels and you’ve got enough power for the whole planet with plenty to spare. And I’m including everything from international air travel to charcoal burned in mud huts to cook game.
You’ve seen Venus in the sky, right? That tiny (if bright) little dot? That’s how much of the sky the entire planet uses — never mind the thousand-or-so square miles you’d need for our current power consumption.
Engineering on the scale you’re asking about isn’t really comprehensible to humans, even if we can run the numbers.
Another bit of perspective. You’ve seen the Great Red Spot on Jupiter, right? You could fit a half-dozen Earths in it. And the sun is as much bigger than Jupiter than Jupiter is bigger than Earth.
And the sun, huge as it is, is such a tiny fraction of the volume of the solar system — even only out to Earth’s orbit — that, once again, it’s a rounding error.
No, really — the sun occupies 0.0000000001% of the volume of a sphere the size of Earth’s orbit, and Earth’s orbit is so close to the sun that it’s all but invisible on human-sized scale models of the entire solar system.
Cheers,
b&
Your solar volume is 3 orders of magnitude too small.
As to the question: I think the question still contains too many unknowns too be answered. Unlike my views on religion, I’m pretty thoroughly agnostic.
Sorry, make that 5 orders of magnitude.
First, even if it’s off by that much…that’s still 0.00001%, which I think still qualifies for “rounding error.”
But let me do the math again to see.
V = 4/3 * π * r^3
1 Astronomical Unit = 149 598 000 kilometers
radius of the sun = 695,500 kilometers
volume of Earth’s orbit = 1.4×10^37 liters
volume of the sun = 1.4×10^30 liters
The latter divided by the former = 0.0000001.
As a percentage: 0.00001%
Hmpf. You’re right. Wonder where I slipped up….
Cheers,
b&
I’ll concede that we may be able to infer life on extrasolar planets, but are we going to meet them? Or communicate with them? Not likely. Statistically, no.
Although I would love it.
I’m pretty sure I’ll live to see the day that NASA announces it’s found an exoplanet with an atmosphere with concentrations of gasses that can only be explained by an active biosphere.
I also wouldn’t be at all surprised to find microbial life on Mars (quite likely genetically related to terrestrial life, considering all the asteroidal bombardments that have tossed rocks back and forth).
I’m not too optimistic that I’ll live to see a robotic expedition that lands on a Jovian or Saturnian moon, but, if I do, it wouldn’t surprise me if such turned up microbes not related to us.
And there is a very, very, very remote chance that Arecibo will pick up a signal from a technological civilization.
Anything else? Not a chance. All the other options are statistically on a par with “all the air molecules might spontaneously move to the opposite end of the room and I’ll suffocate.”
Cheers,
b&
Excellent summary.
Ditto.
Yes… pretty much that.
I’m still kind of optimistic for Jupiter’s moons… maybe even Jupiter itself…
/@
It was buried in my book of a comment below, so let me just pull out in reply here why I’m not quite willing to write off the possibility of interstellar civilizations entirely:
First, they’d have to be near the center of the galaxy, where there are a lot more local stars.
Then, let’s say the civilization is actually made up of AIs running on something equivalent to our computers. Digital life, as it were.
Now, all they have to do to colonize another star is get an advance team there once. Once they have done the setup, now citizens of this interstellar community can “travel” from one outpost to the next at exactly the speed of light using relatively little energy. Of course, they are not so much “traveling” as they are cloning themselves remotely, and there are all sorts of existential issues involved. I am quite sure that such beings would be untroubled by what seem to us to be overwhelming existential issues, though.
There’s definitely no interstellar communities out here in the galactic boonies. And there are probably no interstellar communities of meatbags anywhere. But I don’t think interstellar communities of AI are necessarily implausible in a dense enough region of stars.
As I note below, the levels of ionizing radiation in the galactic core wouldn’t be very conducive to biochemistry and would cause a hell of a lot of communications interference. An advanced AI is going to need to reliably throw around insane amounts of data, and the core is going to be the hardest part of the galaxy in which to do so…never mind, of course, how much energy you’d need to do the trick even out here in the boonies.
Claude Shannon wasn’t very kind to the SciFi notion of beings of pure thought, I’m afraid….
Cheers,
b&
Okay, the ionizing radiation thing could be an insurmountable problem… As far as energy and data rates, I’m seeing an argument for impracticality here, but not an argument for impossibility. And I’m not generally willing to declare anything “permanently impractical” — if it’s not impossible, than there could be ways of engineering around the impracticalities that we just can’t imagine.
How far out from the core do you have to get before the ionizing radiation is comparable to what we’ve got in this neck of the woods? Are there regions of space where you’re pretty dense with stars, but not inhospitable to life-as-we-know-it?
I’m not enough of an engineer or an astrophysicist to answer those questions…but, well, stars are the main source of radiation, and the more densely you pack them, the more radiation you get. Also, densely-packed stars tend to be in star-forming regions, and are therefore mostly made up of young, big, hot, energetic stars.
In other words, the more you do to overcome the one problem (distance) the more you do to make the other worse (excessive radiation).
My gut tells me that you’re not going to get a technological civilization in an environment much harsher than what we face here on Earth. Life, yes, sure — but that’s not asking for much. But life-as-we-know-it would suffer far too much damage from ionizing radiation to survive here without our atmosphere…you’d be stuck with simple organisms that devote all their resources to genetic damage control.
NASA can’t use all the fancy latest-and-greatest gadgets because radiation in orbits wreaks havoc with them. Everything needs to be shielded, simplified, made multiply redundant, and dumbed down. There are physical limits at work…in an environment with so much radiation, you can expect an IC of this die size to flip so many bits over so much time, and for so many circuits to be permanently destroyed at such-and-such a rate.
I’m getting off-topic here, but it turns out your generational “sleeper” ship would need either a full-fledged chip fab just to keep the computers running, or it’d need to haul around an insane amount of lead shielding…and that’s ignoring all the rubber and plastics that’ll outgas, turn brittle, and crack and fail. And all the rocket fuel and atmosphere that’ll leak out through the solid steel tanks like helium out of a toy ballon. And on and on and on and on.
You can go to the stars fast, and need the output of a star to get you there. You can go to the stars slow on a generation ship that needs to keep an advanced civilization happy for longer than humans have been growing crops, which means the stored energy output of a star. Or you can go slow with a “sleeper” ship that needs just as much stored resources and industrial capacity to keep stuff from breaking down along the way. And there aren’t any other options.
Now I really gotta get back to work….
Cheers,
b&
Whoever said anything about integrated circuits? I said “something equivalent to our computers”. Perhaps better would be to call it a general purpose data storage and processing device capable of supporting an artificial intelligence.
We know for sure that this is possible because I have one attached to my shoulders right now; it just doesn’t have very good I/O capabilities (and a lot of the important “information” is probably encoded structurally rather than in manipulable signals) so there’s no way to go about transmitting the “program”.
We also know that the general principle of data storage and computation can be solved with a number of radically different technologies, because it’s done by brains, ICs, abacuses, mechanical computers like Enigma, etc.
The only question is whether there exists a technology for data storage and computation that is both a) capable of supporting sapience, and b) surviving interstellar travel (which means being pretty copacetic with ionizing radiation, requiring very low power for very long periods of time, or whatever other constraints you can think of).
I don’t feel at all confident declaring this impossible, certainly not the way I would declare FTL or intergalactic travel impossible. I also won’t declare it possible, either, of course. I just don’t think you can rule it out.
Regardless of the mechanics of computation, Claude Shannon established the theoretical limits…and it’s those limits that are the problem, not the implementation details. There are only so many bits you can cram into a signal of a given energy level in an environment with a given noise floor.
Silicon is a quite adequate order-of-magnitude approximation for the problem.
Alas.
And now I really gotta get back to work….
b&
Well said, Ben. I always enjoy your comments. Chapeau!
This is all so right. I’ve spent my career engineering things that have to work reliably for long periods of time (or people die). (“Lay”) People really don’t get it at all, in so many ways.
“What do you mean random radiation causes bit flips?! You have to stop that!”
[Well, no, all we can do is mitigate and make redundancies: weight, cost, space …]
“How can you set a value on a human life and make engineering calculations (horrors!) based on that?!”
[Well, we know that if you add this feature/safeguard to the system that it will icrease the cost this much and that will increase this risk over here due to cost avoidance and then X people will die because of it …]
all of it is carbon-based — yes, it’s theoretically possible with other chemistries, but nothing else comes close to carbon in terms of ubiquity and usefulness.
Something I always wonder – could it be the case that we just haven’t *figured out* how other chemistries could be as useful as carbon? Surely we haven’t proven the negative here (not because it’s impossible, but because it seems in this case very difficult to do). It’s the same thing I say to IDists – just because you don’t know how it happened, doesn’t mean there wasn’t a way it could have happened. Scientists are spending most of their energy looking for Earth-like life, but I’m not convinced that, if it were possible for fundamentally different life to have evolved, that our small minds would have been able to figure it out whether ever having seen it.
It comes down to chemistry, stellar evolution, energy budgets, and evolution. Carbon does the most interesting things of any of the candidate elements, it needs the least energy to do its thing, and stellar evolution means it’s ubiquitous.
All the other options would be quickly out-competed by carbon before they had a chance to establish themselves. Any environments hospitable to the alternatives would either be more hospitable to carbon or would be so nasty that nothing would be able to do the trick.
(Of course, that’s not to say that somebody won’t someday create a silicon- or other-based biochemistry as part of a science experiment, but only as a result of a civilization that started with carbon-based life.)
Cheers,
b&
+1
On the other hand, we don’t have a very clear picture of the chemistry going on at the surface of exoplanets. One can at least imagine there being many, many planets on which the temperature is too high for carbon, which is very reactive, to form stable bonds the way it does here on earth. Under such conditions, you might get silicon based life in a HF medium or something similarly weird.
Good points, regardless. I think you’re right that carbon-based life is much more probable than other types but I wouldn’t be surprised to learn that under certain conditions other forms of chemistry out-compete carbon-based ones.
I recall reading an article by Stephen Gillett years ago in which he argued that a sulfur-rich world with highly acidic oceans would favor silicone chemistry over carbon chemistry. Can’t vouch for it myself, not being a chemist, but it’s an intriguing idea.
There’s always the possibility of that, of course, but I’m with Ben that it seems unlikely. Imagine a being who knew not a single thing about organic chemistry, hadn’t even seen a living organism of any type (not sure how this “being” would be existing then, but go with the thought experiment for now), and only had an 8th grade education in the most basic chemistry…. If you showed that being a periodic table and asked, “Now, if you were going to build a system of different types of molecules so that it had as many combinations and as much flexibility as possible, and you can only use the first three rows of the periodic table (consequence of stellar evolution), which element do you think you’d find most useful?”, if the being was sufficiently clever than it would probably reply with either carbon or silicon, arguing that that way you maximize the number of potential covalent bonds. And of course silicon is much rarer in the universe than carbon.
But what’s still bugging us chemistry-ignorant people is that the periodic table was written on Earth, in a science that has a habit of taking liquid water for granted. Is carbon still the wonderatom outside those conditions?
As Ben stated above, any conditions that were too hostile for carbon to work are likely too hostile for any form of life at all.
Water is not something we’d expect to be rare, since hydrogen is the most abundant element in the universe and oxygen is in the top four.
Are there any atoms that approach the number or variety of bonds that carbon does, in rarer environments? Chemistry-ignorant people have been itching to know.
Cool, thanks for the informative replies.
I’m skeptical of non-carbon life, myself. Boron and silicon both make nice chains (analogous to alkanes), up to a point, but with great difficulty. What is more plausible, at least talking to some organic chemists, is life that does not use water as the “universal solvent”. For example, in a cold environment (like on the outer solar system’s moons), one could imagine something with (liquid) ammonia rather than water.
*without ever having seen it
A Dyson sphere would have a distinct spectral signature and to date a number of searches of spectral databases have been made with no plausible Dyson candidates being located.
For example: http://iopscience.iop.org/0004-637X/698/2/2075/fulltext/
On the other hand it does make for a pretty hilarious solution to the dark matter problem. “OK, who’s been hiding all the stars?”
Cool site, even if it’s a bit dodgy on the placement of cephalochordates.
I’m with daveau above: surely there’s life elsewhere out there, but is it close enough in time and space for us to (1) make conclusive observations and (2) have any communication? I’m betting yes to (1) and no to (2), unless we create some successor species that’s rather saner and more portable and durable for space travel.
We’re already starting to decrease the error bounds in three of the six most speculative terms of the Drake equation. An exciting time for SETI.
Given 500 million worlds in the inhabitable zones of their stars, the odds that I will soon be psychically channeling the thoughts of a half-dozen or so advanced civilizations are simply (under)whelming! Therefore, please send me all your moneys, and I will promise to put in a good word for you. A deal this good can’t last. So, act before midnight!
Single-celled life seemed to appear almost as soon as the earth started to retain liquid water. Then there was a billion or two years before multicellular life (IIRC?). Furthermore, the advent of multicellular life seemed to require particular biological events (probably due to endosymbiosis): acquisition of a nucleus and acquisition of a power plant (mitochondria or chloroplasts).
As a result, I suspect single-celled life will crop up just about everywhere. I wouldn’t be surprised if some exoplanets outside the “habitable zone” of their stars had pockets of unicellular life. My guess is that it’s actually pretty ubiquitous.
But since multicellular life requires very particular and possibly path-dependent physiological innovations I think multicellular life will be more rare than unicellular by many orders of magnitude. “Intelligent life,” by which I mean roughly organisms that communicate using syntactical languages, will be a few more orders of magnitude rarer still for similar reasons. I wouldn’t be surprised if we are currently the only intelligent life in the Milky Way. I would be surprised if earth had the only unicellular life in the Milky Way. I’m about 50/50 on unintelligent multicellular life in our galaxy.
Based on the number of galaxies, I’m quite certain there’s intelligent life elsewhere in the universe but we will never have any experience of that.
I’m not sure that multicellular life will be as rare as you make it out to be. Yes, it took a long time to appear on Earth, but that was largely due to geological constraints. It simply took a couple of billion years for unicellular photosynthesizers to saturate the geochemical oxygen sinks. Once that saturation point was reached and free oxygen started to build up in the atmosphere, multicellular life appeared almost immediately.
Since I didn’t quantify how rare I think multicellular life is your argument doesn’t really contradict mine. In fact, it rather supports it. In addition to nuclei, chloroplasts, and mitochondria we also need to fill up the atmosphere with oxygen which, as you said, took a couple billion years. Since the universe is only about 12-14 billion years old that’s a significant fraction of the history of the universe. Any planetary system capable of supporting life is likely to be much younger than the age of the universe.
There’s also the notion that conditions on the earth might have been especially favorable to multicellular life. Imagine a planet with only 10% of the surface covered by water. This planet is going to take much longer to become oxygenated because there isn’t as much environment available to unicellular photosynthetic organisms.
And by “almost immediately” you probably mean something like “over a period of time several orders of magnitude longer than the amount of time biologically modern homo sapiens have existed”.
You quantified it to this extent:
“I think multicellular life will be more rare than unicellular by many orders of magnitude.”
It’s the “many orders of magnitude” I’m questioning.
Sure. But your argument is essentially: “Oh, well we just need a bunch of oxygen and then the transition happens magically.” I don’t believe this happens magically. I think certain preconditions need to be met and that is the basis of my argument. You added another precondition on top of the ones I listed, and your precondition took several billion years on earth. I think this actually strengthens my argument for the rarity of multicellular life relative to unicellular life.
I’ll admit to taking the same approach with the emergence of unicellular life, sort of just hand-waving it into existence. So I’ll admit that unicellular life might be much more rare than I’m allowing for.
It’s all speculation anyway, but you’re certainly not going to convince me that multicellular life is common by implying it’s somehow inevitable.
I didn’t say it was inevitable or magical. I’m just pointing out that the time lapse between the geochemical preconditions for multicellularity and the emergence of multicellularity is comparable to the analogous time lapse for unicellular life. To me that implies that we should expect the likelihood of multicellularity given photosynthesis to be of roughly the same order or magnitude as the likelihood of life given hot rocks and water.
Or is your argument that photosynthesis itself is a rarity, and that most life in the universe never gets that far?
Actually my argument is just that it takes so freaking long to develop photosynthesis and then sufficiently oxygenate the atmosphere that the vast majority of instance of unicellular life have not yet evolved any multicellular life. This isn’t an argument that unicellular life won’t usually (eventually) develop into multicellular life. It’s an argument that, probabilistically, most unicellular life hasn’t done this YET.
Consider a planet with a whole lot less surface water than earth and a whole lot more atmosphere. Instead of taking a couple billion years of oxygen production to allow multicellular life maybe this place takes a couple hundred billion years. From the perspective of human beings that will almost certainly not be around in a few hundred billion years that is very nearly equivalent to never developing multicellular life at all.
Does that make more sense than I was previously making?
Put that way, yes, it does make more sense.
To be fair to you, “many orders of magnitude” is probably a stronger statement than I should have made. There’s some question of what I might mean by “many” but “several” would probably have been a better word. I certainly don’t think unicellular life is 10^100 times more likely than multicellular life or anything ridiculous like that.
It seems extremely unlikely that there is no other life/intelligent life in the universe.
I have a feeling, however, that way out here in the galactic boonies, we will never encounter it. If we do, it will probably be restricted to simple contact, i.e. we know somebody else is out there, but we can’t really communicate. (There may be unintelligent life in our solar system, which we could well discover, but I think the odds are somewhat against it at this point… though not tremendously against)
FTL travel is not possible. A universe in which it was simply stops making sense. Causality disintegrates, and badly.
If our civilization is at all typical, technological civilizations tend to be naturally radio-bright for only a century or two. It’s wasteful in the extreme to shoot high-powered radio signals in all directions at once, when you really just want to communicate to somebody on the other side of the planet. Long distance communication will use more efficient means such as fiber, and wireless applications will be employed locally and therefore use low power digital signals. Even at our radio-brightest, you’d have to be looking right at us to have heard. I imagine other civilizations have similar trajectories.
We are so far out on the galactic spiral that there are just not that many stars within a manageable number of light-years from us. Unless intelligent life is absurdly common, as in 1 in 10 stars or something, we’re probably just way too far away from any neighboring civilization to ever make physical contact.
If we happen to be running an Active SETI program at the same time another civilization is running a SETI-type program (or vice versa) and we happen to point at each other at the same time (well, not the same time at all actually… but you know what I meant!) then we might make radio contact.
NOW. All that being said, I imagine the situation could be quite different near the center of the galaxy, where there are dozens of stars within a few light years. If intelligent life is at all common, making radio contact there might be trivial. There might even be enough civilizations within a handful of light years of each other to establish a galactic community of sorts. It would take generations to work it out, as each fumbling step in establishing a conversation would have a turnaround time of years. But if we know we’d hear a reply back from the Zergians every 60 years or something, I bet we could get something going after a while.
Depending on lifetimes of the organisms involved and on what types of propulsion technologies are practical, etc., it might even be worth it to send emissaries on a generation ship or something. It’s an enormous cost, but if you know exactly where you are going…. well, it might be worth it.
We might even imagine some sort of AI life where they can “travel” (well really, clone themselves remotely) at the speed of light, as long as they already have a receiving station set up. You could have a thriving galactic community in this case, if the technology ever turns out to be practical. It wouldn’t be anything like we’d imagine, and there are all sorts of crazy existential issues involved in that kind of “travel”. But it’s not impossible.
Perhaps such a thriving galactic community would even deem it worthwhile to engage in a massive Active SETI type program to search for wayward civilizations in the backwoods of the galaxy. And maybe someday they’ll point their transmitters at us.
Of course we’d still be stranded… if this hypothetical community lives near the center of the galaxy as I have posited, it would be over 50,000 years before we could get a response to any reply we might send. And you can forget about traveling there!
But maybe someday, we’ll find ourselves briefly bombarded by untold petabytes of data from a thriving galactic community living in the core of the galaxy, and while we’ll never be able to participate in that community, we can smile and know we are not alone.
I’m not holding my breath 🙂
That’s quite romantic…but the galactic core is thick with ionizing radiation which will wreak havoc with both biochemistry and communications….
Run the numbers on the power requirements to transmit a signal across interstellar distances, and you’ll see that you’ll be stuck with either a monstrous energy bill or a data rate that makes the Pony Express seem like 100GigE fiber in comparison.
b&
Boring, likely answer: there is no other life in the universe, or if there is, anything nearby is scummy monocellular gunk.
Awesome science-fiction answer: At some point in the past (and remember, there’s billions of years of “past”), alien life got multicellular, got intelligent, and started making long-term plans for existing in Deep Time. With an eye toward efficiency, it optimized itself and the world around it to maintain its existence for as long as possible by exploiting various loopholes in the laws of physics so subtle we probably can’t even understand them yet. We don’t notice aliens because they’re not little gray men or even cool postsingular computronium shells floating around stars; they’ve built themselves into the fundamental substrate of reality and operate as efficiently as possible–so efficiently that we can’t distinguish them from natural phenomena. SETI isn’t going to detect anything, because SETI is built to detect waste energy (radiation); life that focuses on maintaining itself across Deep Time doesn’t give off enough waste energy to detect.
If the history of a technologically advanced civilization meeting a less advanced one on our own planet and among our own species is anything to consider, we should be afraid.
Very afraid.
After all, empathy is evolutionary advantageous only in one’s own group/clan and family. If you care for your own, your genes will flourish, whereas caring for those outside your group, other than to sustain a breeding population, is wasted effort.
Empathy outside the immediate collective is an accquired trait and we have no reason to believe it’s a commonly accquired one even if life turns out to be common in the universe.
Maybe countless civilizations have arisen in the Milky Way alone, only to destroy themselves soon after.
If we do find life outside Earth, we’d better hope it’s microscopic or of limited intelligence at least until the laser/railgun/plasma death ray equipped spaceships from Earth Command are ready and we have a fully trained legion of marines ready to man them.
Or, best case scenario, they don’t think we’re worthy of First Contact and avoid us altogether.
Except that we have many, many examples of members of one species going out of their way to save the life of a completely different species — even of an enemy species. (Think of a female dog nursing a kitten.)
Empathy may be much more common than we suppose.
Exceptions don’t make a rule, and they won’t tell you the overall trend for an entire civilization. But I still think eksith is being too pessimistic. The ability to cooperate with non-kin might not have evolved genetically, but it is necessary for our existence as we know it. It could become a rule for our species, or others, through some means other than genetic evolution. It’s probably doing that right now.
All life on earth is kin to other life on earth. The more similar it is– the more recent its common ancestor. Life on another planet would not be our kin, but our genes aren’t necessarily specific in regards to who or what we cooperate with or are compassionate towards. We seem to operate on more general “programming”– we care for life forms that seem to care. I’m extrapolating this to mean that other “intelligent life” (life that understood that it evolved –and that other life could have evolved on other planets) might be similar to us in this way.
I’m not sure if there is life elsewhere; I’ll give it some thought after I look for some around here.
But I do want to thank you for saving my soul, by leading me to http://www.discoverlife.org/mp/20m?tree=1&res=1200&b=WHF_LIFE. I could never figure out (in spite of the availability of Holy Scripture, AKA “South Park”) what was the right religion for me. And now you have gifted me with Holy Revelation!
It turns out that, all along, I have been a Bilaterian of the Chordate Rite, Amniote Synod! Thank you!
Ever hear of tardigrades? These are virtually indestructible DNA-based life forms that:
“can survive temperatures of close to absolute zero (−273 °C (−459 °F)), temperatures as high as 151 °C (304 °F), 1,000 times more radiation than other animals, and almost a decade without water. Since 2007, tardigrades have also returned alive from studies in which they have been exposed to the vacuum of outer space in low earth orbit.” -Wikipedia
I can see no theoretical reason to prevent an alien life form from having a reproductive phase (“spore”) with these abilities. Such “spores” could be launched all through space in economical little capsules that would revitalize the organisms upon contact with a suitable world. Time and distance is of little consequence for this kind of travel.
And then there is Deinococcus radiodurans, a bacteria that:
is capable of withstanding an acute dose of 5,000 Gy of ionizing radiation with almost no loss of viability, and an acute dose of 15,000 Gy with 37% viability. A dose of 5,000 Gy is estimated to introduce several hundred double-strand breaks (DSBs) into the organism’s DNA (~0.005 DSB/Gy/Mbp (haploid genome)). For comparison, a chest X-ray or Apollo mission involves about 1 mGy, 5 Gy can kill a human, 200-800 Gy will kill E. coli, and over 4,000 Gy will kill the radiation-resistant tardigrade.
Time and distance is of great consequence for this kind of travel.
– DNA will be broken down by cosmic radiation over time, and not repaired due to the frozen state.
Even if protected from stellar radiation inside asteroids, DNA will not survive long enough to get to the next planetary system.
– Tardigrades have a horribly low survival rate after such jaunts as described here. They won’t go far.
– Same goes for bacteria, as they randomly from the spore state to ensure population survival in new, potentially benign, environments that they haven’t seen before. Bacteria spores will die off over geologically short time. It is questionable if transpermia works between planets even because of that.
“Same goes for bacteria, as they randomly from the spore state” – Same goes for bacteria, as they randomly awake from the spore state. [I am sure you can get many references on that here. This killed my transpermia interest for good, so I dunno where I stashed those refs.]
It’s the same fundamental problem as interstellar travel.
Physics places certain limits on the time and energy needed to make the trip. Physics also places upper limits on the time that organized matter (life, technology, whatever) can survive entropy and on the amount of energy that can be applied to the job.
Turns out that there’s no solution to the equation — the limits don’t overlap.
Cheers,
b&
Can you supply some references for this claim? Could clever shielding buy time, particularly for a really small “spore”? For small enough things, the energy needed to escape a solar system would not need to be great. It seems to me it would be tough to prove that there is no solution to this problem.
I don’t have any references…it’s just my conclusion from running the numbers various ways over the years.
Take your example, of shielding a spore. You’d need a lot of shielding…several inches of lead, at a minimum. As a result, your engines now have to have that much more oomph…and you need that much more fuel and / or reaction mass to power them.
Worse…how are your spores supposed to escape from being encased within a massive lead sphere? You need an active mechanism for releasing them…and that mechanism — and your propulsion system — has to survive functioning in interstellar space for tens of millennia, if not more. No plastics or rubber allowed, unless you plan on re-fabricating them from raw materials along the way…which means industrial processing, with huge stores of energy and raw materials…and all that for a single microgram sample that might land in a pool of lava?
Better build thousands, hundreds of thousands of them…or you could just build a few city-sized ships (you’re already up to skyscraper-sized at least) with crews…but, if you can live in interstellar space for several times as long as human civilization has already existed, why do you care about seeding some distant planet with microorganisms?
Cheers,
b&
Ben, several inches of lead around a tiny thing is not going to be that heavy. Something the size of Voyager (now headed out of the solar system, I think) could carry lots of those balls. Once outside the solar system, make the thing explode like a shotgun shell or put little motors on each ball, and let the cosmic billiard ball game begin.
If they are well-insulated, time does not matter. We are recovering decent DNA from 50000 yr old stuff here on earth. No need for speed.
For landing, the forces experienced on impact would be severe enough (and different enough from any other forces experienced on the trip) to pop open a well-designed lead ball.
Arguments about needing enormous energies and masses seem to me to be similar to arguments about limitations on computer miniaturization. Back in the days of room-sized computers, would anyone have imagined that a single transistor could someday replace them?
I suppose the hardest problem to solve would be that these balls would almost all end up getting sucked into suns rather than planets. But even that might be solvable by some very simple photochemical reaction that preferentially emitted atoms on the sunny side of the ball.
My only point is that there seems to be no real impossibility.
Seems to me there’s a third possibility: that life on Earth is just one branch of a monophyletic group spanning the solar system or (less plausibly) the entire galaxy.
It may not be very likely, but at this point I don’t think we can rule out the idea that the first replicators on Earth arrived from elsewhere. We do know that Earth and Mars have exchanged mass (rocks blasted off Mars by asteroid impacts fall to Earth as meteors), and that the young Earth was heavily bombarded by comets. So cross-contamination by primitive life is not out of the question (even without the help of UFO aliens).
Similarly, it’s dynamically possible for comets originating around one star to be ejected from its gravity well and captured by another star. If comets carry life (and we can’t say for sure that they don’t), it could in principle spread from one planetary system to another by this mechanism.
Whether such spaceborne life exists or extends to the galaxy at large remains an open question. I would not bet heavily on the possibility, but it’s at least conceivable that the galaxy is teeming with life genetically related to us.
(Disclaimer: that fact that I consider this exogenesis hypothesis conceivable does not mean that I endorse the “plagues from space” and “mutations from space” crackpottery promoted by Wickramasinghe and Hoyle.)
I’m quite certain there are other life forms in the universe.
Sadly, however, they don’t all look vaguely human and they don’t all speak English while guiding their star ships.
>99.99999% of life forms will not be intelligent (just like here on Earth). And the technological challenges of deep space travel — absent a massive leap in our ability to navigate through worm holes or some such — will mean that we’re likely to never find that tiny fraction who are.
Of course they don’t speak English, they speak French.
Crazy gibberish!
You’ll have to define “intelligent” first.
I gave what I think is a precise and useful definition of intelligent life above:
“organisms that communicate using a syntactical language”
That rules out all earth life except human beings. AIUI, no researchers have yet found syntax in any animal utterances besides those of humans.
Actually, bee dances might technically have syntax, so the definition might not be as useful or precise as I had hoped.
Bee language lacks recursive syntax (phrases nested within phrases), which human languages have.
So? Put a bee nest in a bee nest, and you will have as much recursivity as you need it to be(e). =D
Interesting. But then, Dan Everett claims that the piraha (human hunter gatherers in Brazil) don’t have recursive syntax in their language either so there’s a real possibility that recursive syntax is actually a cultural innovation rather than a feature of our biology.
Then again, maybe “intelligence” in the way we mean it is a cultural innovation in the first place. It’s a tricky problem since we know so little about the origins of human cognition.
What’s the status on that claim about the Piraha, anyway? Has it been replicated/followed up upon?
As it happens, I’ve for a while thought of the “recursivity” claim interesting, in part because we know that the Turing machine model is an idealization anyway – after all, no human *actually* has an unbounded amount of memory.
My opinion is that there probably is, but we’ll probably never know.
Potential for finding life in the solar system: sub-surface Mars (MSL will be there later this year); around geothermal activity on the floor of Jupiter’s moon Europa’s under-ice ocean (lot’s of gravitational tidal forces causing internal heating); potentially the same on Saturn’s moon Enceladus (where water outgassing is occurring from large cracks in the ice); and something completely different in the Methane lakes at Titan’s polar regions. A currently proposed mission is for a probe to fly through the ice plume of Enceladus to possibly find life chemistry remains. Also proposed is the Titan lake floating lander (TiME… for Titan Mare Explorer).
For exo-planetary systems, NASA had planned the Terrestrial Planet Finder (never went forward because of congress). It was a massive multi-mirror interferometer telescope that would have been able to take spectra of exo-planet atmospheres. If there was a large proportion of oxygen in the atmosphere, it’s likely there is at least plant life (cyanobacteria, etc), since primordial planetary atmospheres should not include much O2. That’s if the exo-life uses the same type of metabolism as on earth.
Then, of course, there are the Zeta Reticuli. 😉
My emotional response is that it would be extraordinary (and humbling) if there were no other life other than on our Earth in the entire universe. My second emotional response would be to ask why the hell we are gleefully decimating life on this planet.
The scientific answer is that we cannot know unless we understand well the conditions of every planet out there until we find life. Which may be simply some type of bacteria.
All this talk of aliens reminds me that it’s time to re-read The Black Cloud. Now there was an interesting alien.
It is likely there is life as we know it other places in the universe. Physics as we know it does not offer much hope of going out and making contact. Two major non FTL ideas in science fiction have been a generation ship which would travel for hundreds or thousands of years, or a deep sleep ship, where the inhabitants are held in suspended animation for hundreds or thousands of years.
So physics as we know it won’t get us there. But then we have only had physics as a science for a few hundred years. What will our physics be a hundred, a thousand years, from now? In any case, I hope we go to them, rather than they come to us, given our experiences in human history.
“So physics as we know it won’t get us there.”
It depends on how you define “us”. Physics as we know it is certainly capable of transmitting a digitized human genome and a substantial fraction of human culture across interstellar distances, if there’s somebody on the other end to receive it and instantiate it.
True, but the power required for the job is far from inconsequential.
Any hams out there care to do the math? Assume an Arecibo-class receiver and something of the same engineering scale for the transmitter, and generously assume both are in stable dedicated orbits constantly pointed at each other…what’s the data rate at 10 ly (for the closest stars)? 100 ly (for a big enough volume for there to be a chance of another civilization)? 100,000 ly (to cover the whole galaxy)?
How big a system do you need to get consumer-grade broadband data rates at those distances…say, just one Mbps to make the math easy?
b&
There is practically no chance we’ll ever chat with aliens, even assuming we could visit them. After all, dolphins are clearly intelligent and clearly “talk” to each other, and we still can’t understand each other.
+1
There are other primate species, and birds, who are capable of communicating with us using simple sign language. I don’t think communicating with a sufficiently intelligent alien life form is beyond the realm of possibility, if we find one.
I guess we don’t know just how inaccurate the Drake equation is until we actually figure out abiogenesis, but my impression is that it is head-over-heels optimistic.
It assumes that [ne = 2 (all stars with planets will have 2 planets capable of developing life]which could well be off by a factor of a trillion, for all we know.
What are the essential characteristics of the Earth which make it rather unique, and just how fortuitous is our (an intelligent and social species) existence?
Earth must have a high-speed rotating iron core, a single very large (non-rotating(?)) moon at a particular distance. The odds of this alone seem astronomically high against.
It needs all this and still needs to have a lot of water, plenty of land, enough light, a very small temperature variation. It needs to have retained its atmosphere, which needs to have the right components and ph. It needs to have plate tectonics.
We needed just the right timing and amount of near life-ending asteroid impacts to ensure that we would emerge. The dinosaurs seemed to have a pretty good thing going for a very long time without the need for anything more intelligent or social than raptors. Again, astronomical odds against?
There are probably ten other essential characteristics I don’t know about.
Intelligence is not a particularly adaptive trait. I just saw James Hanson saying that if we are really unlucky, we may have already passed the point where a runaway greenhouse is inevitable, where our seas will boil away and the Earth will for ever be in the same state as Venus. We have only had a truly scientific and technological society for a couple of hundred years, and we may have already done ourselves in!
I think the reason that we don’t hear anybody out there is because there isn’t anybody out these. And until we DO hear someone else out there, I think the null hypothesis should be that …they simply ain’t there.
Quite a bit of that is either not actually necessary or a related process of some of the other parts.
A moon really isn’t likely to be needed. Earth without the moon would be different, but not so different that it would be uninhabitable.
If you’ve got an Earth sized planet that’s already the Goldilocks Zone from its sun, the odds are good that it’s going to retain an atmosphere.
You’re also talking about the evolution of a sentient advanced tool-user as if it had to be humans. There’s no reason to suspect it, though. Chimpanzees, bonobos, or capuchins could have ended up with that title instead of humans. Or it could have been some sort of tree kangaroo, a Multituerculate, Maniraptor, or heck, the many generations removed descendent of Terrestrisuchus. All it would have taken would have been the right set of extinctions and mutations.
Also, the idea that greenhouse emissions are going to cause runaway levels of heating that result in the Earth being driven to a Venus-like state sounds more like the plot of a bad Hollywood disaster movie than something that’s backed up by climatology.
If you are skeptical about the runaway greenhouse, take it up with Dr Hanson, he is a lot more qualified than I.
It is my understanding that a large moon is required for abiogenesis, as tides are needed for mixing actions, wet/dry cycles, etc.
Our moon is evidently the result of a massive collision of two planetoids, leaving the two bodies we are familiar with. The odds of that happening again seems ridiculously small.
I am not requiring humans. All apes are here because dinosaurs are not. Because of the good timing of a just-so sized asteroid impact.
The question is just how overly optimistic is the Drake equation. Right now all we know is that life developed on Earth only, and Earth has some very unusual characteristics.
If we aren’t sure how abiogenesis occurred, how you say that a large moon is required?
Incidentally, you say the earth has some very unusual characteristics but we only really know about our own solar system in any detail. Sounds like a mighty small sample to me.
As you say, if we’re not sure about the mechanisms for abiogenesis/biopoiesis, it’s not clear that a large moon (i.e., one, or more, with significant tidal effects) is required, or even beneficial.
However, Asimov, “The Triumph of the Moon”, suggested that the tides were necessary for life to move out of the oceans and that was necessary for intelligent creatures to emerge.
Although intelligence can arise – has arisen — in the seas, it’s not clear what technologies they could develop: How would they discover how to smelt metal, for example?
/@
Well, if we did it, others can. Actually, I think it’s more interesting to ask how common is technological life? (I hesitate to use the work “intelligent”). Agreed, it’s a pretty small sample, but it took more that 4 billion of the 4.5 billion years that the earth has existed for technological life to arise (to the best of our knowledge)
“It is my understanding that a large moon is required for abiogenesis, as tides are needed for mixing actions, wet/dry cycles, etc.”
There are other forces than a moon that can produce mixing actions. Heated vents, like the ones in our oceans, spring immediately to mind.
Um…hello? Solar tides? Hydrologic cycle? Geysers? And the #1 motive force behind waves, namely wind?
If you think lunar tides are a requirement for abiogenesis…well, then, may I interest you in some prime Arizona beachfront property?
Cheers,
b&
What – do you think I am making this stuff up as I go? Astrophysicists think a large moon is required. Go figure. Better yet check out the Rare Earth wiki.
Correction some astrophysicists think that a large moon is required. They have yet to actually demonstrate it.
I’ve only had time to skim this thread so far, but it seems to me yours is the first negative answer.
I would argue that the negative answer is the only formally correct answer from a scientific perspective. Until evidence arises to disprove it, the null hypothesis is that we are alone.
Your null hypothesis makes as much sense as a similar one that the Earth is the center of all creation.
Perhaps the most important assumption in all of science is the universality of its applicability. A rock dropped near the surface of a planet with the same mass as the Earth several billion light-years away will accelerate down at 10 m/s/s (within rounding).
Unless you wish to assume that abiogenesis required something more than basic organic chemistry, the null hypothesis would be that, assuming the planet’s other characteristics (chemical composition, insolation, etc.) are comparable, there is also life on that planet…and that its biosphere is similarly rich and diverse.
And while it is true that we have yet to identify any other planets quite that similar to ours, we’re long past the time when it is reasonable to suggest that planets such as ours are nonexistent. The only question is how abundant they are.
And there’s every reason to suspect that Earth-like planets are the exception but nevertheless abundant. Our instruments aren’t really up to the task of finding other Earths, but they’ve already identified a great many other planets with any number of Earth-like characteristics (mass, orbital period, etc.)…just not any (yet) with all the same characteristics.
And all that is assuming that abiogenesis requires something very much like Earth. In reality, it seems much more likely that all you need is something with roughly the same set of raw ingredients and a temperature that mostly keeps water liquid…in which case, the null hypothesis should be that all rocky planets at least a billion years old in the habitable zone of fourth-or-later-generation stars harbor some form of life.
Cheers,
b&
“…And there’s every reason to suspect that Earth-like planets are the exception but nevertheless abundant….”
You have evidence for this? Because I have not heard of any. ;>D
And the fact that we have not been visited or heard a radio signal, ie, Fermi’s paradox, argues against your assertion.
The Earth has a very unique history and for all we know, each vicissitude has been serially crucial for abiogenesis and the evolution of intelligent life. Even if there was a planet that was similar to Earth, there is no guarantee that even monocellular life would develop there.
If the assumptions of the Rare Earth hypothesis are correct, large percentages of galaxies are eliminated from contention right off the bat. Add the unique history of the Earth, and the numbers do not crunch well for abundances of Earth-similar planets.
Here is a report of a new paper from two PhD’s from Princeton claiming to disprove the Drake equation using Bayesian analysis:
http://www.technologyreview.com/blog/arxiv/27025/
I think that there is other life “out there” mainly for statistical reasons and because of the Copernican principle that there is nothing special about the Earth and our location.
Communication? Probably not in the near future though it might happen in some window of time in the future (before everything else has retreated between the relativity horizon)
I would be disappointed rather than amazed if we were all there is.
+1
What a massive letdown it would be…
Well, a massive letdown to us, a huge satisfaction to theists… the universe was created for us after all!!
/@
Galaxies are like living systems too, perhaps “they” are are all around us.
As for protein/DNA life, it’s just the chemistry of common elements in our universe using standard forces in our universe in ordinary environments in our universe. Hells yeah it exists.
Q: Either we are the only form of life in the universe (and by ‘we’ I mean the monophyletic group of organisms that live on Earth), or we aren’t. … and above all why?
A: We observe that life on Earth didn’t occur halfway in on the biosphere lifetime, which is estimated to be ~ 5 – 7 Ga. Let us try a stochastic model to see what we can get out of that.
Abiogenesis, having prebiotic chemistry evolve into protobiotic cellular life, could be a repeated process of attempts over time and locales. In the simplest stochastic model this belongs to the family of Poisson processes.
Such processes stacks their probability mass early, due to their exponential distribution. A homogeneous Poisson process has P(T > t) = e- λt.
This is a testable model.
To simplify we use a normed distribution where observation time t = 1. Since this is a one-sided interval from t = 0, we want to have a set of distributions with at least 0.99 of the probability mass within the interval.
The probability mass is expressed by the cdf (cumulative distribution function). Inserting into the Poisson cdf, we get F(t,λ) = 1 – exp(-t*λ) ≥ 0.99 → t*λ > 4.6.
Now t = 1 corresponds to λ ~ 5. That means the normed waiting time T ~ 0.2. With actual time t* ~ 5 Ga we get actual waiting time T* ~ 1 Ga.
With current understanding we have putative observations of life from ~ 3.5 Ga bp. Earth aggregated ~ 4.5 Ga bp, which means the interval gets close to the required ≤ 1 Ga.
In principle a stationary process means a stationary mechanism in a stationary environment.
This isn’t what happened at the start, since volatiles were collected, temperatures and pressures going down and tectonics started. But since it *looks* stationary it means it was close to stationary in some stochastic sense, even if it was frustrated in actuality.
Further as opposed to other situations in statistics there is no inherent problem with having just one data point for characterizing stochastic processes, though it is lousy as an estimate.
Omitting a discussion of actual frustrated attempts: they will look Poisson, or near enough. The small waiting time is indicative of high likelihood of success and/or high attempt rate. Both translates to deterministic ease.
This is informative.
Let us assume that observations are good enough to push the model into testability, and a test is devised replacing the above rough estimate.
– Abiogenesis looks simple and robust; it is modeled by a stationary Poisson process.
– Abiogenesis looks easy and/or fast; a normed rate is high.
– A habitable planet has a 36 % likelihood of being inhabited at 5 Ga age. After that the likelihood quickly raises to ~ 100 %; it is ~ 95 % at 7 Ga age.
M stars have projected main branch lifetimes in the 100’s of Ga, and super Earth’s projected atmospheric lifetimes in the 10’s of Ga.
QED. =D
We should know, or just about, that there is life in the universe now that we know there are habitable planets and Mars-Earth sized planets. (3 of the latter released just yesterday.)
The tricky question is if there is intelligent life.
Life got started on earth pretty quickly after the planet formed. Also, life is made of pretty mundane chemicals. Considering the size and age of the universe along with these facts, I would guess that life is common out there.
Yes there is life on other planets, I would be suprised if we don’t find some microbial life within our own solar system my money is on Europa!
The interesting thing about this question for atheists is that our ignorance is such that answering it requires something as close to faith as most of us would want to venture. Paradoxically, I am confident that life exists elsewhere, even though we do not know exactly how life began on earth, but I am not so sure about intelligence elsewhere (at least in the Milky Way, which is most relevant) even though we have a good idea of how intelligence came about.
I sure wouldn’t characterize it that way. Go back & reread all the excellent mini-essays posted above and note all the chemistry, physics, statistics, biology, astronomy, cosmology, astrobiology, etc., etc., employed. Doesn’t resemble faith in my book.
I wouldn’t say that this speculation is anything like faith. The conjectures offered here are based on science, statistics and mathematics, etc. More importantly:
1. We know that these are mere conjectures and
2. Most of us would change our minds if new evidence appeared or new physical laws were scientifically proven.
Ask someone who has “faith” what it would take for them to change their mind.
1)Speculation is not faith, but saying “I think the universe is teeming with life” is. Speculation would be saying “the universe may be teeming with life, but there is no evidence, so I am speculating.”
2)The people who claim life elsewhere is likely because the universe is large and therefore life is statistically probable do not understand statistics.
Yes they do. If the odds of an event occurring are 1 in 1 billion, but your sample size is 1 billion squared individuals, the odds are likely that the event will happen multiple times. You couldn’t predict which individuals it would happen to, but trying to say that it wouldn’t happen to any of them is a lack of understanding of statistics.
Eh, no.
I think two plus two equals four, but that’s not a matter of faith.
Faith is a conviction that will persist in the face of contradicting evidence and reason. Simply stating your suppositions or convictions is entirely tangential to faith.
And you’re grossly oversimplifying the statistical argument. It’s not merely the fact that the universe is so big that I’m extremely confident that there’s lots of life “out there.” It’s the size of the universe coupled with the ubiquity of the prerequisite conditions for life combined with the overwhelming evidence that life is as much a given in the right circumstances as is crystal formation.
Cheers,
b&
“Speculation is not faith, but saying ‘I think the universe is teeming with life’ is.”
Nonsense. Thinking is not faith; it’s the opposite of faith.
There is an SF story about aliens coming to earth. They were friendly and cordial with humans, but they were here to visit with the dolphins.
So Long, And Thanks For All The Fish.
Statistics strongly suggest that we aren’t alone in the universe, but until we understand the principles of ambiogenisis I can’t have a reasonable certainty.
Space is big. You just won’t believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.
So… yeah, highly probable.
Just as it is highly improbable that we will ever see live higher developed than single cell organisms in our lifetime.
Let’s not forget what that same author had to say about the population:
Although you might see people from time to time, they are most likely products of your imagination. Simple mathematics tells us that the population of the Universe must be zero. Why? Well given that the volume of the universe is infinite there must be an infinite number of worlds. But not all of them are populated; therefore only a finite number are. Any finite number divided by infinity is as close to zero as makes no odds, therefore we can round the average population of the Universe to zero, and so the total population must be zero.
I think I just dissolved in a puff of logic…..
I hate when that happens (to me).
A very small number divided by a very large number is still a number.
I have rarely enjoyed a thread more than this.
Thank You
+ 1
“Exhilarating” is the term that comes to mind.
For what it’s worth, there has never been a satisfactory natural explanation of 1977’s “Wow!” signal, a signal received by Big Ear with hallmarks of what we might expect from extraterrestrial communications.
I don’t think it proves anything, but it’s a data point, at least.
If there is, we’d better set up the Covenant before they set one up and start wiping out planets we live on. lol
Plausible, requiring evidence.
There are just far too many suns similar to our own and to many planets in the juxtaposition of our own to the sun to say there is no other life. The question might be what kind of life? Not that it would really matter, but it will be fascinating to those exploring the universe in the distant future to find out that life on other planets may be far different then we expect. Yep, I do believe that not only is there life out there, but I accept the idea that much of that life is intelligent beyond our capacity of understanding.
I have rarely enjoyed a thread more than this.
Thank You
The answer to this question must surely be ‘yes’. We live in an infinitely large universe. And life seems to have got going very early in our Earth’s history. I would therefore be far more surprised to find that we are the only form of life than I would to be to find that we aren’t. The progress of our knowledge gained from science has pretty consistently shown that we humans and our planet are far from special. I think that trend will continue and in future we’ll find that life is ‘commonplace’ where the conditions for it are right.
Given our knowledge about the universe, how many one of a kind events do we know about? The only ones that come to mind are those such as the Big Bang and possibly abiogenesis on Earth, such events preclude recurrences because they overwhelm the conditions that lead to the event. Otherwise, the types of things that exist are abundant, lots of galaxies of repeating types, lots of suns of repeating types, lots of black holes, lots planets of repeating types, lots of repeating types of life on Earth. Within our solar system the Earth is unique but within the Universe suns like ours are abundant. Given the nature of the Universe how would it even go about doing something of a given type one time?
I wonder if some of you abundantly knowledgeable folks would apply your thoughts to the odds of the Universe producing something once and only once? Would it be mathematically, chemically or physically possible? I think there is other “intelligent life” because the Earth and the Sun don’t seem in any way unique, they formed out of disks of matter and we see disks of matter everywhere we look.
Maybe there could be some kind of life forms on a couple of the planets or moons in the solar system, I hope we find some life there somewhere. The other suns in this part of the galaxy are a very long way from each other, maybe we will find a way to infer the existence of life but, we are remote and any meaningful contact isn’t something that I would plan on or worry about.
I believe in the Dawkins view of aliens. IF they exist, they wouldn’t look like humans, because the evolution of another being wouldn’t evolve the same way humans have. They’d look like something of a different world.
I think that the constraints of nature mean that life forms if they exist elswhere in the universe would follow the dictat of Natural Selection which would MAKE things look similar if they inhabitet a similar niche – eg fish shaped if in water & a swimmer, upright with opposable digits if they were going to make tools.
By the way, it really bugs me that films with aliens in space ships often show aliens who would have difficulty creating tools to make those ships because of those constraints!
By this point in the thread, it’s pretty redundant to vote Yes, and anything I might have offered in support has already been covered, infinitely better, by a previous poster. A tremendous read; thank you, brilliant WEIT community!
While I’m as pessimistic as most about the chance of living to learn of any contact with intelligent aliens, the romantic part of me still remembers the hopeful, idealistic mindset behind the Sagan-designed plaques on the Pioneer & Voyager probes, and loves to imagine that someday, “someone” will recover one of them and start to wonder…
I always thought that the plaques were for those sending the probes far more than any who might someday recover them.
And, let’s be honest. As unlikely as it may be, our children are far more likely to recover them than any other species….
b&
Much like funerals are for the living, and prayers are for those who do the praying. Still, I like Diane’s romantic notions.
Oh, me too. And I still say that Sagan was one of the greatest poets of the 20th Century.
b&
“Science is the poetry of reality.”
(we all know who.)
So true. Which is awfully wistful to think about. I suppose it was just my youth at the time, but things seemed so much less cynical then. Per aspera ad astra . . .
I concur. This has been a tremendously interesting post.
Like many people above, my suspicion is that simple life (eukaryote-like) is very common but intelligent life (us-like) is incredibly rare.
I suspect that we will meet von Neumann machines created by an intelligent species long before we meet an intelligent species itself. Let’s hope they aren’t berserkers.
Well you learn something new every day.
The Rare Earth hypothesis
(Google: The term “Rare Earth” comes from Rare Earth: Why Complex Life Is Uncommon in the Universe (2000), a book by Peter Ward, a geologist and paleontologist, and Donald E. Brownlee, an astronomer and astrobiologist.)
contends that the Drake equation is way too optimistic.
The Google entry, here, talks about it:
http://en.wikipedia.org/wiki/Rare_Earth_hypothesis
Not to offend, but I detest that whole line of work and its basis in bayesian ‘betting’. There is bayesian modeling and there is bayesian bullshit. The Drake equation is the former, the Rare Earth idea is the latter.
In the Drake equation you can exchange initial estimates for observed frequencies, say the now more or less constrained frequency of exoplanets. And you have a firm model of known factors, making the model potentially testable.
In the Rare Earth idea you can never firm up the number of factors. This means it is never testable as a whole. (Which is why I don’t think it warrants to be called a hypothesis in the first place.)
As it happens, some factors put in the original proposal has now been rejected. For instance, old studies of planetary tilts never accounted for the rate of change:
“Lissauer and his team conducted a new experiment simulating a moonless Earth over a time period of 4 billion years. The results were surprising – the axis tilt of the Earth varied only between about 10 and 50 degrees, much less than the original study suggested. There were also long periods of time, up to 500 million years, when the tilt was only between 17 and 32 degrees, a lot more stable than previously thought possible.”
Scratch “need large moon” from considerations of planets conducive for “complex life”.
You wouldn’t need to “firm up” the number of factors to test the Rare Earth hypothesis. You could confirm it by testing whatever factors you have, just as you could test the factors in the Drake Equation.
And you’re far too quick to dismiss the “need large moon” factor. One study is hardly conclusive. Even if it is conclusively demonstrated that a large moon is not necessary for the development of complex life, there are lots of other factors identified by Ward & Brownlee suggesting that such life is rare, perhaps vanishingly rare.
No offense taken! We are all just kicking around a ball for fun.
I have seen somewhere a claim that a large moon is required for enough tidal gravity force to cause plate tectonics – no idea if this is off-base, but possibly another requirement demanding a large moon.
This whole discussion is interesting to me because this Rare Earth hypothesis was published in 2000, yet my introduction to many of the arguments forwarded by its authors were part of the first section of the best class I ever took at college – Intro bio for bio majors in 1972. The section started with cosmology, then traced evolutionary forms post abiogenesis. I was an English major at the time. The course had me switching to biology as a major.
“If you are lost in the jungle, do you cry for help? Who knows what may be lurking in the shadows. Friend, we hope, foe, for certain.”
If there is only life on 1 out of every 250 million galaxies. Then there are still 400 to 2000 galaxies that contain other forms of life. (I used 100 billion galaxies to calculate 400 and 500 billion galaxies for 2000.)
Now whether they are intelligent? I’d say it is possible maybe up to 5 of those planets in those 400-2000 galaxies that contain life are similar to us! I know it sounds insane but it happened here so why not!
The laws of physics as expressed in chemistry are the same everywhere, and the requirements for what something has to do to be called “life” really aren’t that complicated — reproduce, acquire energy and process it, process information through a sensorium to interact with its environment. There are plenty of life forms on this planet that do that and look damn weird to us. It’s reasonable to expect that there’s “life” out there that is based on different chemistries, and doesn’t look anything like what we’d recognize as life — but it does all the stuff our type of life does. Sentient life now — ahhh that’s different, but still not impossible — same laws of physics.
What we don’t know-Intelligent life other than us, life on mars. life else where.
We are so lucky to see other planets.
The thread got really long before I got to comment so forgive me if someone has said this already. Life existing in freezing cold polar waters and also around boiling hot volcanic vents gives me hope. Some say that Venus is too inhospitable for life but I think that they forget that life evolves to fit into its environment. I am 53 years old, I live in hope that even really primitive life will be found on another planet or moon in my lifetime.
Also, rock eating bacteria that have been found miles below the surface suggest that sunlight may be overrated.
My take on it: there is other life in the universe. Simple life is probably common: one inhabited planet in maybe every 10-50 star systems or so. But intelligent life is probably very rare. My guess is there may be 100 or so civilizations in the Milky Way–which sounds like a lot, until you consider that that’s 100 out of 200-400 Billion stars.
My brother and I and at least one other person (who was not present with my brother and I), saw a UFO in 1977. It was a sphere, with 3 large antenna like protrusions, appearing about 2 or 3 times longer than the diameter of the sphere and pointing toward the sky. The sphere and “antennas” appeared to be electrically charged and all the same color (both the sphere and “antennas” were the same color) of a mixture of red, white, and blue, and possibly green (but I forget if green was present). The antennas slowly retracted into the sphere, and almost immediately, the sphere took off at “instant acceleration” (it took off so fast from a standstill to “instant acceleration,” that it appeared to pop like a bubble at first). There was a red streak as the sphere flew into outer space. This is one reason, even though I’m an atheist, that I don’t agree with most atheists that there is no possibility of other life visiting planet Earth, although I have no idea why that life would do so. What other explanation could this be (assume I’m telling the truth, and I am)?
What is more likely, that an alien spaceship visited earth undetected by any military or civil surveillance of that you three were mistaken?
There was absolutely no chance we were mistaken. All three of us saw the same thing. Hallucinations are out (three of us were unlikely to hallucinate the same thing, especially since we weren’t all together at the time of the siting). My brother and I didn’t know about the woman seeing the UFO because she was not with us, yet she reported the same thing the next day (she worked at the same place as my brother, which is the reason we found out about her the next day). Her co-workers were making fun of her about seeing the UFO until my brother said he saw the UFO too. No drugs or alcohol were involved (with my brother and I, but I don’t know about the woman). So, I can’t explain what we saw or what it was, but I know we weren’t mistaken about seeing the same thing. No supernatural explanation is necessarily involved (after all, life could evolve elsewhere since it evolved on Earth), but the indications are “intelligent propulsion” of some type (for example, the “antennas” retracted before the sphere sped off) and it is unlikely that in 1977 humans had any “warp speed” type craft. I have a difficult time “arguing” with theists when I have seen a probable ET craft, yet almost all atheists deny that such craft are here (“you saw the ET, most atheists deny ETs are here, so just because atheists don’t believe in ETs that doesn’t mean that god doesn’t exist”-in short, if I can believe something without evidence that can be proven, then they call me irrational for not believing that a god exists without evidence).
On the other hand, you three have have 35 years to compare notes, swap stories, and reinforce each other’s beliefs about what you think you saw. So you can’t really claim this as three independent sightings.
By now there’s no way to know what you actually saw, regardless of how clear it seems in memory. That clarity is not a good indicator of reliability; quite the opposite. Memory is not a videotape of events as they actually happened. It’s a story we tell ourselves about what we think happened, and the more times we tell it or go over it in our minds, the more we reinforce our (inevitably flawed) interpretation of events, and the farther it gets from the original reality.
So if you want to convince us that you really did see an actual alien spacecraft, you’re going to have to muster a lot more evidence than your 35-year-old memory and your assurance that you’re not making it up.
Memory can play enormous tricks. Many years ago I witnessed a stabbing. I remember being asked by the police what colour the knife was and I remember saying that I saw light being reflected off the blade but it was too dark to see anything else about the knife. I also remember saying something similar in court. As I recall I was telling the truth in both cases. But now I remember, quite clearly, the assailant visibly holding a knife with a blue handle, the very knife that was presented as evidence in the trial. Now at least one of these memories must be false, but at this distance in time they all seem clear to me.
I agree that atheists can be mighty dismissive about such things. This is probably because the events you described border on the miraculous, and therefore require really strong evidence. It is legitimate to question your memory, as some of the commenters do, but they have not had the courtesy to ask you whether you and your co-witnesses wrote accounts of your experience immediately after it happened. They just assumed you didn’t. That is unfair of them. Did you?
Mass hallucinations is an oft described phenomena. People influence each other, and memories are dynamic.
This is why we have the saying “plural of anecdote is not data”. Eye witnesses are worthless as a basis for any empirical conclusions. (They can form a basis for empirical investigations though, or we wouldn’t have courts.)
It doesn’t even have to be a hallucination, either. Viewing something at an angle, especially if it’s in the sky and you can’t tell how far away it is, can make it very hard to recognize objects that would otherwise be familiar.
I once watched a UFO flying over my grandparents back field for over 20 minutes before I finally realized that it was a black trash bag that had somehow gotten caught in an eddy about 200 feet off the ground.
I’ve also watched small airplanes coming in for a landing on an overcast day at twilight- silhouetted against a gray sky they looked a lot like flying disks until they got quite close.
Ball lightning. Possibly. More probably, at least. “Ball lightning has been described as transparent, translucent, multicolored, evenly lit, radiating flames, filaments or sparks, with shapes that vary between spheres, ovals, tear-drops, rods, or disks.” [Wp]
/@
I saw what turned out to be a crescent moon situated atop a domed light fixture in a rural area, took me a long time to figure it out, looked just like some of the UFO pictures, bright on top, dark in the center with an extended stream of light thrusting out from the bottom.
appeared pop like a bubble at first
So..what happened when it got to second? 😉
Sorry, but illusions especially at night are really common.
“So, at the risk of encouraging loons of all varieties to post here,”
Since it appears no loons have posted, here is a Canadian 1 dollar coin (commonly called a Loonie) with a picture of one loon:
http://en.wikipedia.org/wiki/File:Loonie_reverse_view.png
Having drunk at the well of Nick Lane, I will assert…
(a) on an earth-like planet, the rise of life is nearly inevitable.
(b) but the rise of eukaryotic life is a highly improbable event.
Thus, there may be many planets covered in dull, boring bacterial mats, but very few with eukaryote-equivalents.
Evidence: bacterial life arose very early in the earth’s history. Eukaryotic life arose some billions of years later and, most importantly, only once. All eukaryotes have a common ancestor.
However, Lane implies that the rise of eukaryotes was tied up with the atmospheric oxygen level increasing. Thus, if photosynthetic bacteria arise, perhaps eukaryotes aren’t far behind.
All speculation of course; and I may have grossly misunderstood what Nick Lane has to say on the matter.
The question is moot, of course, since we will never know.
Check this out:
http://www.psi.edu/pgwg/images/Jan12Image.html
This is really exciting. It is similar to the red/black soil catena common on Earth. To have it on Mars indicates a tropical climate with plenty of water. I can hear the monkeys screeching and the birds singing now…
Glenn
Are we going to a radio quiet(er) civilization? A civilization could go to a non radio based communication technology, and it would go quiet.
We may never find intelligent life in the universe. I’m not sure if there is any on earth. Smart, yes, intelligent?
I can only see free oxygen as being a tag for life. I think there is likely a lot of life in the universe, hundreds of billions times hundreds of billions equals a pretty good chance at lots of life.