There's an entire genre of these kinds of books that extrapolate generalities (life throughout the Universe) from a single data point (life on Earth), but the truth is, that's not even an educated guess.
We do not know if our evolutionary pressures are universal. We do not know if the evolutionary solutions developed here are appropriate even on other Earth-like planets, much less everywhere. Sensitive dependence on initial conditions could lead to radically different planetary environments, necessitating radically different mechanical solutions to survival, some (many, most?) of which we will never have even imagined.
What creatures would form under an intense magnetic field? In methane? In close orbit around a dim star? In a hot cloud nebula? Could we even recognize them as alive, much less intelligent? Definitely not if we're looking for bats and monkeys and octopuses
No, I think the whole genre of "life is much the same everywhere" suffers from a profound lack of imagination
Physics and chemistry impose some serious constraints on all life forms. On earth we have convergent evolution, independent groups of species independently develop similar solutions for a specific problem. Life on other planets will have similar problems, e.g. reproduction, locomotion and perception of its environment, and its solutions will probably be similar to the ones we have on earth.
First we need to decide how intelligent are the dolphins, then let us look at the stars.
Every single life form on Earth today had exactly the same time to do its evolution in. Us, bats, dolphins, tapeworms, birch trees, amoeba, mushrooms, all of that had exactly the same chance(s) in the same time span.
And we don't even know if and how mushrooms and trees communicate, let alone if they "think", for our near-sighted definition of thoughts. We don't even know what to make of birds, e.g. crows, with respect to the size of their brains and what they can do.
Is our planet, taken as a whole, alive, in some form of the Gaia hypothesis? The correct answers as of this time are either "we don't know" or "it depends on the definition of alive."
That Star Trek trope of "everything in the Universe is just like us with different faces" really needs to be put to rest.
Even H.R. Giger was boring and unimaginative with regards to how he envisioned the Alien. That's clearly a creature influenced by Earth-ism - a quadruped, with a single head and mouth and a flexible spine and claws, it's basically a weird cat.
But changes in the environment and initial starting point can result in very different approaches. For example land mammals, reptiles and fish are quite different from each other. Because they've "always been here" we don't appreciate how different they are. Imagine if we had no fish and then found a planet with water that had fish in it -- that would seem absolutely shocking to see animals that could breathe underwater.
> Physics and chemistry impose some serious constraints on all life forms.
On earth's carbon based life forms you mean. Its a huge blindspot, basically monkeys looking for other monkeys. If we believe our life is sufficiently compelex biochemically, it figures that other "life" may have the same complexity but with very different structures.
So the argument for ET life to have almost exact homologs of terrestial life is bordering on naievete at best, and dangerously intolerant at worst.
The example of convergence between fish and dolphins, birds and insects, the infamous "why does everything evolve into crabs" study and so on should tell us that while we should be open for radically different forms of life, the most likely outcomes will look like something we've seen here on Earth.
I'm personally expecting something like 80% humanoids and 20% exotic forms. Maybe I'm primed incorrectly by cheesy soap operas and sci-fi TV shows, but I think they're not far off (even if for unrelated reasons like SFX/VFX budget and character empathy).
The convergence between dolphins and ichthyosaurs is even more remarkable. Ichthyosaurs were marine reptiles; air breathing tetrapods that, like dolphins, had ancestors that walked on land but eventually returned to the sea to kick fish ass.
Sure, organisms that already share a massive amount of commonalities can diverge and then converge again.
What about the branches that happened early on? We essentially have only two lineages of macroscopic organisms that are actually fundamentally different: Plants and animals.
I would expect any kind of macroscopic extraterrestrial life to be at least as distinct from Terran plant and animal life as they are from each other.
I completely disagree. I think the 'life can look like anything' (lets call them LCLLAs) train of thought suffers from a lack of understanding of constraint satisfaction.
Think about how some LCLLAS talked about how silicon life is probably a thing. First off, it it were, given Earth's crust is mostly silicon and its the most habitual place ever discovered, it would have evolved here. but it didnt. It turns out silicon is just too ridged, and to get life going you need all sorts of chemical properties that just aren't congruent to life.
We are carbon / oxygen organisms for a chemical reason. despite the availability of other resources, other forms of lifeforms didn't develop for a reason. maybe other forms of life does exist in some methane ocean on Saturn like planets, but its not going to be very complex, and definitely not intelligent life building space ships.
I'm just always surprised how can we be so certain? Even here on Earth, for millions of years, life was literally nothing more than single cell organisms - also definitely "not intelligent life building space ships". And it would be very hard to see how could it possibly evolve into such, seeing as the atmosphere was full of incredibly toxic oxygen.
The thing is, life has almost infinite time to evolve out of these various elements. The fact that it didn't evolve here on Earth means absolutely nothing, seeing as Earth alone has billions of years left where such life could arise, and there are literally countless planets everywhere in the universe where the random dice of evolution roll every second.
I disagree with this assessment of silicon based life. While it is true that Earth's crust is mostly silicon, it's also at a temperature that would make metabolic processes using silicon very difficult until you get down to the mantle.
It could be that silicon based life is in fact constrained by temperature and can only arise in planets where the mean temperature is in the thousands. This could in fact mean that we do have a parallel silicon based biosphere underneath our feet. There is obviously no evidence for this whatsoever but then again, there is no reason to assume that the occasional leakage in the form of volcanic eruptions would leave any trace that we could use to deduce that these samples were once living entities.
What's the path-dependency-ness of life? Like, once you have carbon based life to what degree does it preclude silicon based life from evolving? How often does a feature evolve sui generis when the nich that the feature exploits is already filled? Clearly it happens sometimes so if you've got a good enough angle you can step into something that's seemingly already covered.
For all that after several billion years it's just carbon based life forms in these parts. You'd think that there must be some area where silicon based life would provide an advantage. Unless it's a case that carbon based life is an overwhelmingly superior product but on some hypothetical world it's simply filled with silicon and there's virtually zero carbon.
"Other forms of life didn't develop for a reason" isn't that convincing of an argument. We are somewhat knowledgeable about what chemical and physical processes can occur between, -100c to 1500C under 1atm or so, +-100 nanoteslas, in a timescale of under a human attention span. Beyond that, we become increasingly clueless.
We have only a single very specific data point. That, and the human tendency to opine confidently about that which we cannot know.
Well, stage one to silicone life could be computer chips.
Then for a transition period, the shell could be metallic followed by integration of the human mind to that almost indestructible body shell.
Something like the bad guy terminator 2.
But step one could be computer chips. Human designed and made rather than by strict definition of natural selection.
> First off, it it were, given Earth's crust is mostly silicon and its the most habitual place ever discovered, it would have evolved here. but it didnt.
If we assume for a second that silicon life is a thing, would it be reasonable to think that it would be utterly alien? Probably it's chemical composition would be entirely different, but would it be unreasonable, that it could evolve eye, muscle, bone etc. analogs just like us, and the end result would be not entirely unfamiliar to our earthly eyes? The article talked about wings being one of the few viable modes of flight, and Richard Dawkins has made a lecture about eyes having evolved independently multiple time here on earth (like in, as the article states, mammals or octopi).
Weir’s latest book goes into this. (Ex: Audible hearing is based on the distribution of frequencies generated when solid bodies collide or rub.)
On the other hand, If life is that which can use an energy differential to create more order within it (an entropy pump) then sure there are likely forms of “life” out there that we’d have a harder time imagining (that perhaps operate at physical scales and timescales beyond us — thinking nebulae)
> Audible hearing is based on the distribution of frequencies generated when solid bodies collide or rub.
... in Earth-like conditions, and useful in Earth-like conditions. Vibration of denser or rarified gasses could require other solutions to exploit, if it's possible at all
> If life is that which can use an energy differential to create more order within it (an entropy pump)
Now that's the ticket! Under this definition, I suspect most life in the Universe is not carbon based, but far more exotic (to us)
> What creatures would form under an intense magnetic field? In methane? In close orbit around a dim star? In a hot cloud nebula?
Before the question of what you have the question of if.
Then you have the question of continuous constraints. Sensitive dependence on initial conditions still has to operate in a constraint space, and maybe constraints for complex adaptive living systems are much tighter to begin with. Tornados are also sensitive to initial conditions, they are even self organizing, but they are not living beings for example.
Imagination is fine when you’re not burdened by starting a working system from first principles. Conceivable sounds probable when you know less about the constraints.
> Before the question of what you have the question of if.
Meh. I mean, sure, when all is said and done, everything is constrained by physics and chemistry and imagination has no bearing on this reality. On that we agree, to the point that stating it outright is almost a non-sequitur: a true statement that has no relevance to the discussion at hand.
Human culture, in the 400 years of since the first glimmering of the scientific method, has made gigantic leaps in understanding objective truths about our Universe and what lies within it.
At every step, highly educated people confidently assert that we know all that is worth knowing and everything henceforth will just be filling in the details. At every step, these assertions have been a failure of imagination.
I can confidently state with only historical evidence to go by that our current understanding of the Universe is deeply flawed and will be completely overturned someday. Or if not, it would be because we're just not intelligent enough as a species to do it, and not because we know it all*
It is this sense that I mean, when I say that asserting all life throughout the Universe will have forms like those found here, is a failure of the imagination.
* Everything that we ever will discover is constrained by the form of our bodies, our evolutionary history, our psychology, and to a lesser degree by our cultural outlook and worldview. There are truths about the universe that are literally forever beyond our discovering because we are incapable of discovering them.** Were we to encounter alien entities that made use of such hypothetically inaccessible principles, especially if their physical forms were based on them in some way, we would literally not understand what we're looking at.
** As an aside, that is my favorite explanation for the Fermi Paradox, that the interstellar cosmos is thrumming with the signs of life and civilization, but we only partly and minimally understand what we're looking at, and so miss these signs.
On the one hand, the conditions under which some lifeforms are thriving here on Earth are already pretty extreme.
On the other hand, indeed, we may not yet be in a position to be able to imagine, realistically, all that we would (eventually) agree to call a lifeform. (Life built from phonon "particles" in a planet-size crystal, anyone?) Sure, there may be constraints, such as life, in a meaningful sense, may only be realizable based on polymers, in which case the conditions must be such that they allow polymerization of simple substances to take place.
> On the one hand, the conditions under which some lifeforms are thriving here on Earth are already pretty extreme.
Not really. They are all within +/-5km of the planet surface, live under 1g of gravity, as a rule, are not exposed to X-rays, gamma rays, cosmic rays, strong magnetic fields or nuclear radiation, or extreme temperatures. There's nowhere on Earth that receives more than about average solar radiation or gets much above 100C where life survives.
Life generally has access to ample oxygen, though a few anaerobic organisms exist. They're all DNA-based, have access to ample amino acids, aren't bathed in thousands of completely toxic chemicals, have liquid water (and not, e.g. liquid methane). The list goes on and on.
Yeah, there are a few extremophiles, but they are by far the minority, and are clearly adapted incrementally from other organisms that evolved in non-extremophile environments. In essence, there's a large reservoir of easy-pickins living that generates biodiversity to cross over into extremophile environments.
Now imagine 5x the gravity, 100-1000x the solar irradiance, the lack of magnetic field (and thus direct exposure to solar winds), no atmosphere, or atmosphere entirely composed of a toxic gas, extreme exposure to X-rays, etc. The universe is full of many places where Earth life, even extremophiles, would have no chance of survival. And such places don't have reservoirs of biodiversity from which to adapt to these conditions. They're just dead.
> (Life built from phonon "particles" in a planet-size crystal, anyone?)
It seems unfathomable to me that life could be composed of bosonic particles, since Pauli exclusion seems to be one of the most important reasons why matter (never mind living organisms!) has the property of spontaneously structuring itself in a rich and complicated way.
Agreed. At a bare minimum, human thought patterns have to be rare. At some point we're either going to murder ourselves or create a Von Neumann machine capable of interstellar flight. After that humans or human-derived machines will fill the universe. Since that obviously hasn't happened with alien machines, the aliens are either not alive or totally unlike us.
I don't agree that human thought patterns have to be rare, or your other assumptions. The only safe bet in this discussion I think, is, we don't know anything for sure.
> At some point we're either going to murder ourselves or create a Von Neumann machine capable of interstellar flight.
There are many, many possibilities for human futures that are between those two and not do extreme. It is absolutely possible we survive millions of years without interstellar travel or self destruction.
> Since that obviously hasn't happened with alien machines
I also think it is not so obvious that this hasn't happened or isn't happening with alien machines. It certainly could be and we would not know either way. A la 2001: A Space Odyssey, perhaps in fact we are a product of alien machines themselves.
There is a book Accelerando by Charles Stross that talks about why neither case might be true - he shows a scenario where life ultimately transforms its host system into a matrioshka brain. At that point distance from the cloud is reduction in bandwidth to the parts of yourself that exist in that cloud- if the matrioshka brain can simulate billions of planets and leaving it makes you incredibly stupid by your normal standards why do it?
> At a bare minimum, human thought patterns have to be rare.
Definitely. In fact, I think they are almost certainly unique in our entire local galaxy cluster, and we will never find anything even close.
We could very well find something interesting, enlightening, sophisticated or using what we might be able to squint and call technology, but I suspect we will never find an alien civilization intentionally broadcasting for example the fibonacci sequence or prime numbers so that we can learn to exchange culture and communicate ideas.
> At a bare minimum, human thought patterns have to be rare.
I'm not so sure. We can't even be sure if cetaceans, in particular orcas, have thought patterns similar to ours. Of course, they lack the physicality and environment to develop written history and knowledge and also technology, but we currently have no way of knowing what their thoughts are.
> Could we even recognize them as alive, much less intelligent?
If we focus on recognizable features, we may look for organisms with self-replication skills (a feature of living organisms) and prediction skills (a feature of intelligent organisms).
On the intelligence aspect, the skill to predict the future in general, and imminent threats in particular is useful for structured organisms less resistant than rocks to survive. On that matter I wonder, do unicellular organisms on earth have prediction skills?
What also helped those fragile structures to continue existing along rocks after a long time might be their ability to replicate themselves before being destroyed. Reproductive skills might actually be the first interesting feature to look for in extraterrestrial organized structures.
> we may look for organisms with self-replication skills... and prediction skills...
Sure, but I imagine this is easier said than done. We 21 c. humans would be most likely to recognize as intelligent life something obviously not a natural feature of the landscape, that operates on a time scale under a year and above a split second or so, that predicts that which we can predict, and most importantly has a form corresponding to Earth creatures. Without ticking all those boxes, especially in a truly strange chemical environment, we will have people asserting that they are a complicated chemical processes, but in no sense alive the way we are alive, if we can even recognize them at all.
Of course the environment will determine life forms. What the article says is that if there is a gaseous atmosphere, for example, then selection will reward animals that are able to move through it. That means for organisms that are heavier than the surrounding atmosphere - most likely - wings. For liquid environments, there probably aren’t that many locomotion techniques that are both effective and missing on earth, meaning when we see something swimming in water on a different planet it’ll look like a jellyfish, octopus, fish, worm, clam, bacteria, shrimp, horse… or one of the other hundreds of ways of swimming
Once we move outside Earth-like conditions, we should be decreasingly confident about our speculations, not more confident. What are the chemical and physical conditions of a hydrocarbon lake at 5g, -180C, 1 kilotesla and 100 atmospheres? Can we really be confident that "whale" is the best mechanical solution for moving around there? Can we really be confident that "moving around" would even be the best survival strategy? I think not.
>There's an entire genre of these kinds of books that extrapolate generalities (life throughout the Universe) from a single data point (life on Earth), but the truth is, that's not even an educated guess.
Hey, whatever sells a pop science book pounded out over a long weekend.
It's funny how sure everyone was about slowing expansion of the universe and the idea of close rocky planets/distant Jupiters, but only lucky guessers are remembered.
It could simply be that patterns for lifeforms on Earth were set so long ago that everything sort of rhymes. Veer that path at the beginning and you end up with a significantly different answer.
Nah. Think of fish - and the assertion "There's no such thing as a fish." That refers to the similar evolution of many branches of life that ended up "looking like a fish" but are otherwise unrelated.
They had a common ancestor of a coral-like sea squirt (If I remember right). That looked nothing like a fish.
We humans have only our definition of life form. These are limited by physics and our logic.
However, we can't even see the whole universe, with no scientific break through, we never will.
We don't exactly know the full story of the big bang, we can't explain the very beginning.
We don't know what happens in black holes, our logic rules literally breaks down there.
I could well be that there are life forms which we couldn't even imagine, which are not limited by our known physics.
We know a little bit about space time and gravity and the elements.
Dark matter still unexplained, no universal formula for everything in sight, i have seen DNA mentioned, maybe some creatures do not need any DNA.
Too many factors are unresolved, we don't know whether there have been, are or will be totally different species.
Imagine, at one point in history, earth didn't even exist, before animals, there were only bacteria.
Earth lifetime is nothing on the grand scale of things. Humans are a more intelligent version of very common mammals.
With a couple more things gone wrong, like a flu or smarter predator animal in the past, humans might have never come to be.
I greatly appreciate scientists and people discovering and accumulating the knowledge, and I understand the scientific methods have to be followed accurately, else we diverge into pure speculation.
But limiting possible alien life to earth like planets might not be all there is.
> The universe could possibly avoid eternal heat death through random quantum tunnelling and quantum fluctuations, given the non-zero probability of producing a new Big Bang in roughly 10^10^10^56 years
I used to explain to myself what was before the universe - that it simply didn't exist, just like myself didn't exist, but in fact my body is a continuation of life since its inception - like my parents knew their parents (or at very least they had a brief contact with their mothers), their parents knew their parents and so on back to something that sparked life, but that something also must have come from something. So still can't get my head around what was before the universe.
I know these visualisations that show for example that something that has beginning and end can be divided infinitely, but when I picture it, this exists in some sort of space.
I expect that there are some things that are "universal" and some that aren't.
For example, if life--any life--forms on a planet, it is likely that some macro-organisms will evolve that consume other organisms.
On Earth we have plants that are eaten by animals that are eaten by other animals and so forth and these all act as a form of "battery" in that solar power is converted into energy and increasingly stored in larger "blobs". This is almost necessary for large life to exist. Well, for carnivores at least (eg many whales eat krill and there are a bunch of filter-feeders).
So the chemistry of life elsewhere may be similar or it may be totally different but something like a carnivorous trait is I think almost inevitable.
Once you have that then certain other traits became almost inevitable. Flight, for example. It may be that flight is impossible given local conditions (eg high gravity, atmosphere or the lack thereof). That doesn't mean we'll end up with feathers and birds per se but evolutionary pressure will likely mean available niches are filled. On Earth almost every environment has life, only really excluding the coldest, driest, highest and deepest of places.
Also, consider sensory organs. I expect the ability to detect parts of the EM spectrum, sound, taste/smell and tactile feedback will all likely evolve with sufficient time. And that itself has consequences for what life looks like.
Great read, thanks. This is a very interesting subject to me. A couple of years ago I read a theory about alien life that was a bit different from this:
Given the age of our universe, sun, earth and humans:
Universe 14 000 million
Sun 4 600 million
Earth 4 550 million
Earth Life 3 500 million
Humans .2 million (200,000 years)
The probability of some alien life being within say, a range of [-.5 mllion, .5 million] of the life on earth is VERY slim. It is most likely that life out there is either in very early stages (protezoric) or that it is way farther than our current form (how will humanity look like in say, another 500,000 years?, assuming it continues to exist and evolve)
First, the article wasn't about human-like technological civilization, but just about life in general. And there are species of animals alive today that have hardly changed in 100s of millions of years. So Kershenbaum would be right if we found some life-forms that vaguely resembled for example a Coelacanth on some exoplanet.
Second, you're ignoring the fact that life as we think of it can really only evolve around at least 3rd-generation stars because you need enough heavy elements. That cuts the age of the "life-capable" universe by at least half, so the window of relatively modern life on earth with respect to the age of the life-capable Universe really isn't that small... let's say 350My out of 7Gy, so about 5%.
Unless we just happen to have evolved very early on compared to what's normal, we should expect a lot of intelligent life with just a little bit of variance on these numbers. And some of that could easily be millions of years old. Interestingly, even if a life form populated new solar systems at a rate of a thousand years per system (where each populated solar system in turn populates more of them), they'd still fill up the Galaxy in only a couple million years.
Unless "intelligent" life inevitably renders its local environment uninhabitable and collapses in short order - a proposition looking more likely by the day. It may be that the intelligence required to maximally exploit the local negentropy is strictly less than the intelligence required to not do that, despite being able to. Indeed it's difficult to see how the trait of "behaving responsibly with an entire planet" could evolve - the selection pressure is rather all-or-nothing.
Why is intelligence seen as some inescapable playbook of evolution?
Evolution has no agenda or goals, other than to select for survival. Most species on this planet have a low intelligence yet are successful, and don't seem to evolve into the direction of intelligence.
That makes it sounds like it took 1 billion years for life to form. According to timelines I've read about (based on scientific papers) it took around 800M-900M years for the heavy bombardment to stop, and temperatures reduced similar to those of today. So once an environment friendly to life appeared, life appeared quickly.
The preferred chirality of organic molecules could absolutely have arisen by chance, but it's an interesting to see this in meteorites.
On the unrelated subject of handedness, I saw an interesting thread on Twitter today [1] speaking about how we're starting to synthesize reverse chirality polymers and enzymes, most notably DNA and replication enzymes.
There are a lot of interesting implications.
You can't get rid of L-DNA without reverse DNase, leading to an accumulation of information and transcription. So they need to remake all the enzyme steroisomers.
That alone is interesting, but you can take it further to the limit and produce reverse biology that synthesizes reverse sugars that can't be metabolized by much of extant life [2]. Suddenly a lab-escaped reverse autotroph can out-compete all of us right-handed lifeforms because nothing can eat them. Bacteria, plankton, the entire food web collapses. When we have nothing left to fish or farm, we die too.
Never thought nanotech's grey goo was plausible. Now I see something that rhymes with it, and I could see it happening within our lifetimes.
It'd make a crazy MAD bioweapon on par with or potentially worse than nukes.
The first type is incidental: we've already encountered meteorites from Mars and the Moon, for example, so it's not hard to imagine life bearing material arriving that way.
The second would be intentional: either ET seeds planets or merely visits them with contaminated boots or probes.
Either way, we would pick up some DNA from offworld.
His article completely ignores the possibility of engineered life. Engineered life can bypass evolution and natural selection, even if the species responsible for the engineering was a product of evolution.
Heh and what if the engineer even introduces evolution and what he truly engineers is code-based chemical cells that can conquer, survive, evolve and expand from anywhere ? :D
I'd do a life myself, I'd make it post-metallic, post-silicon, post static: I'd make it use water and carbon, so that it can exist everywhere. I would make it so that it can become intelligent on a small time scale, say a few billion years, all on its own, from scratch, on any rock :D
Not saying we have an engineer, but you think of engineered life as you are now as a simple software programmer. But an engineer in 500k years trying to expand more, would probably think of chemical automata that can evolve and adapt in harsh conditions. Say for instance if humanity decided it would be enjoyable for life to exist on Jupiter. It'd have to make something that can try a lot of variations with a very simple first formula to consume whatever gas there is there and survive whatever pressure.
Engineered life still follows evolutionary pressure and natural selection it just might not hit the same walls as life that is only driven forth by random mutations and opportunistic gene exchange does.
Strong arguments can be made that the ability to become a multi-planetary civilization requires you to master the tech tree that includes engineered life.
The first life we encounter from another civilization might not be evolved at all. Presumably a civilization with the capability of interstellar travel might also have the technology to manipulate the underpinning of life itself.
In fact, if we do discover something from another civilization, it is quite reasonable that it would be some sort of Von Neumann probe. It might be made of mechanical parts, "biological" parts, or something in between.
A Von Neumann probe would be highly engineered, and might have no trace of evolution to it.
I recall a scifi story by Stephen Baxter where a human-made probe on Mars eventually evolved into advanced, aware, spacefaring Von Neumann probes. After a few million years, one curious probe traces serial numbers back to Earth in search of their creators. However, humans had devolved back into a type of monkey that was directly symbiotic with a literal tree of life. The probe concluded that such a primitive creature could never have developed technology, and left.
>> A Von Neumann probe ... might have no trace of evolution to it.
Except that the very fact that it exists represents many evolved traits. If they are sending probes then their are either curious or expansionist, both evolved traits tied to competition for resources and/or survival. A species totally devoid of any history of evolutionary pressures wouldn't act that way, which is one of many possible great filters: once we have access to the infinite resources of space, perhaps we just stop caring and don't bother expanding. Such logic allows us to learn much simply from the existence of an otherwise silent Von Neumann probe.
But when dealing with infinity, we must appreciate the likelihood of the unlikely too.
Personally, I favor the prospect of the insanely lucky idiot race, that clumsily and completely by chance manage to launch a probe so seemingly sophisticated that every sentient race that discovers it readily submit to its perceived superiority.
Well also, a Von Neumann probe is a type of life. It's very unlikely that a self-replicating machine would not develop it's own technological drift in the replication protocol.
Not only that - for all we know a biological civilsiation could have existed 3 billion years ago which then spawned a machine civilisation that now has as much relation to its distant origins as we do to some prebiotic soup on Hadean earth.
> It might be made of mechanical parts, "biological" parts, or something in between
Or just a digital clone of a once-biological being that can live for infinity exploring the Universe. Why would you explore the Universe in a meat suit?
Or it could be designed to be very small so as to efficiently send out at near light speed, and designed to quickly adapt and replicate in any hospitable environment.
Unless it somehow came from nothing, then there must be some pathway from what came before to what they have now (thus evolution). It might be a long pathway, which is so long that it's hard for us to see the beginning from the end, but that doesn't invalidate the argument that it will still have characteristics of something that followed such a pathway.
If Star Trek taught me anything, it's that most aliens look like humans, except for some bumps on their forehead. Hodgkin's Law of Parallel Planetary Development.
Star Trek TNG kind of lampshaded that in "The Chase", where its is revealed that alien species are similar and biologically compatible because they share a common humanoid ancestor.
I read somewhere that the most likely "alien" visitor is a bacterium, virus, or other organism that rode here on a meteor fragment. That achieves interstellar travel without the need or intelligence or intent. It was also the subject of the terrific movie The Andromeda Strain.
This is interesting, and I have a more mathematical way of thinking about this.
If we were somehow able to segment evolutionary pressures, and normalize their values such that they sum to one, I'd hypothesize that as the average evolutionary pressure goes to zero (meaning high number of evolutionary pressures that are generally uniformly distributed), then this author's hypothesis is true. But as the average evolutionary pressure grows (fewer pressures, or highly skewed distribution of pressures), I imagine it would lead to VERY different looking life. I'd also hypothesize that as the average value increases, it leads to system instability.
Readit News
We do not know if our evolutionary pressures are universal. We do not know if the evolutionary solutions developed here are appropriate even on other Earth-like planets, much less everywhere. Sensitive dependence on initial conditions could lead to radically different planetary environments, necessitating radically different mechanical solutions to survival, some (many, most?) of which we will never have even imagined.
What creatures would form under an intense magnetic field? In methane? In close orbit around a dim star? In a hot cloud nebula? Could we even recognize them as alive, much less intelligent? Definitely not if we're looking for bats and monkeys and octopuses
No, I think the whole genre of "life is much the same everywhere" suffers from a profound lack of imagination
Every single life form on Earth today had exactly the same time to do its evolution in. Us, bats, dolphins, tapeworms, birch trees, amoeba, mushrooms, all of that had exactly the same chance(s) in the same time span.
And we don't even know if and how mushrooms and trees communicate, let alone if they "think", for our near-sighted definition of thoughts. We don't even know what to make of birds, e.g. crows, with respect to the size of their brains and what they can do.
Is our planet, taken as a whole, alive, in some form of the Gaia hypothesis? The correct answers as of this time are either "we don't know" or "it depends on the definition of alive."
That Star Trek trope of "everything in the Universe is just like us with different faces" really needs to be put to rest.
Even H.R. Giger was boring and unimaginative with regards to how he envisioned the Alien. That's clearly a creature influenced by Earth-ism - a quadruped, with a single head and mouth and a flexible spine and claws, it's basically a weird cat.
On earth's carbon based life forms you mean. Its a huge blindspot, basically monkeys looking for other monkeys. If we believe our life is sufficiently compelex biochemically, it figures that other "life" may have the same complexity but with very different structures.
So the argument for ET life to have almost exact homologs of terrestial life is bordering on naievete at best, and dangerously intolerant at worst.
What are those constraints? Can you enumerate some of them?
Also, physics and chemistry change under certain environments.
I'm personally expecting something like 80% humanoids and 20% exotic forms. Maybe I'm primed incorrectly by cheesy soap operas and sci-fi TV shows, but I think they're not far off (even if for unrelated reasons like SFX/VFX budget and character empathy).
The convergence between dolphins and ichthyosaurs is even more remarkable. Ichthyosaurs were marine reptiles; air breathing tetrapods that, like dolphins, had ancestors that walked on land but eventually returned to the sea to kick fish ass.
https://en.wikipedia.org/wiki/Ichthyosaur#/media/File:Ichthy...
What about the branches that happened early on? We essentially have only two lineages of macroscopic organisms that are actually fundamentally different: Plants and animals.
I would expect any kind of macroscopic extraterrestrial life to be at least as distinct from Terran plant and animal life as they are from each other.
Think about how some LCLLAS talked about how silicon life is probably a thing. First off, it it were, given Earth's crust is mostly silicon and its the most habitual place ever discovered, it would have evolved here. but it didnt. It turns out silicon is just too ridged, and to get life going you need all sorts of chemical properties that just aren't congruent to life.
We are carbon / oxygen organisms for a chemical reason. despite the availability of other resources, other forms of lifeforms didn't develop for a reason. maybe other forms of life does exist in some methane ocean on Saturn like planets, but its not going to be very complex, and definitely not intelligent life building space ships.
The thing is, life has almost infinite time to evolve out of these various elements. The fact that it didn't evolve here on Earth means absolutely nothing, seeing as Earth alone has billions of years left where such life could arise, and there are literally countless planets everywhere in the universe where the random dice of evolution roll every second.
It could be that silicon based life is in fact constrained by temperature and can only arise in planets where the mean temperature is in the thousands. This could in fact mean that we do have a parallel silicon based biosphere underneath our feet. There is obviously no evidence for this whatsoever but then again, there is no reason to assume that the occasional leakage in the form of volcanic eruptions would leave any trace that we could use to deduce that these samples were once living entities.
For all that after several billion years it's just carbon based life forms in these parts. You'd think that there must be some area where silicon based life would provide an advantage. Unless it's a case that carbon based life is an overwhelmingly superior product but on some hypothetical world it's simply filled with silicon and there's virtually zero carbon.
We have only a single very specific data point. That, and the human tendency to opine confidently about that which we cannot know.
Just give it a few more decades ...
On the other hand, If life is that which can use an energy differential to create more order within it (an entropy pump) then sure there are likely forms of “life” out there that we’d have a harder time imagining (that perhaps operate at physical scales and timescales beyond us — thinking nebulae)
... in Earth-like conditions, and useful in Earth-like conditions. Vibration of denser or rarified gasses could require other solutions to exploit, if it's possible at all
> If life is that which can use an energy differential to create more order within it (an entropy pump)
Now that's the ticket! Under this definition, I suspect most life in the Universe is not carbon based, but far more exotic (to us)
Before the question of what you have the question of if.
Then you have the question of continuous constraints. Sensitive dependence on initial conditions still has to operate in a constraint space, and maybe constraints for complex adaptive living systems are much tighter to begin with. Tornados are also sensitive to initial conditions, they are even self organizing, but they are not living beings for example.
Imagination is fine when you’re not burdened by starting a working system from first principles. Conceivable sounds probable when you know less about the constraints.
Meh. I mean, sure, when all is said and done, everything is constrained by physics and chemistry and imagination has no bearing on this reality. On that we agree, to the point that stating it outright is almost a non-sequitur: a true statement that has no relevance to the discussion at hand.
Human culture, in the 400 years of since the first glimmering of the scientific method, has made gigantic leaps in understanding objective truths about our Universe and what lies within it.
At every step, highly educated people confidently assert that we know all that is worth knowing and everything henceforth will just be filling in the details. At every step, these assertions have been a failure of imagination.
I can confidently state with only historical evidence to go by that our current understanding of the Universe is deeply flawed and will be completely overturned someday. Or if not, it would be because we're just not intelligent enough as a species to do it, and not because we know it all*
It is this sense that I mean, when I say that asserting all life throughout the Universe will have forms like those found here, is a failure of the imagination.
* Everything that we ever will discover is constrained by the form of our bodies, our evolutionary history, our psychology, and to a lesser degree by our cultural outlook and worldview. There are truths about the universe that are literally forever beyond our discovering because we are incapable of discovering them.** Were we to encounter alien entities that made use of such hypothetically inaccessible principles, especially if their physical forms were based on them in some way, we would literally not understand what we're looking at.
** As an aside, that is my favorite explanation for the Fermi Paradox, that the interstellar cosmos is thrumming with the signs of life and civilization, but we only partly and minimally understand what we're looking at, and so miss these signs.
On the one hand, the conditions under which some lifeforms are thriving here on Earth are already pretty extreme.
On the other hand, indeed, we may not yet be in a position to be able to imagine, realistically, all that we would (eventually) agree to call a lifeform. (Life built from phonon "particles" in a planet-size crystal, anyone?) Sure, there may be constraints, such as life, in a meaningful sense, may only be realizable based on polymers, in which case the conditions must be such that they allow polymerization of simple substances to take place.
Not really. They are all within +/-5km of the planet surface, live under 1g of gravity, as a rule, are not exposed to X-rays, gamma rays, cosmic rays, strong magnetic fields or nuclear radiation, or extreme temperatures. There's nowhere on Earth that receives more than about average solar radiation or gets much above 100C where life survives.
Life generally has access to ample oxygen, though a few anaerobic organisms exist. They're all DNA-based, have access to ample amino acids, aren't bathed in thousands of completely toxic chemicals, have liquid water (and not, e.g. liquid methane). The list goes on and on.
Yeah, there are a few extremophiles, but they are by far the minority, and are clearly adapted incrementally from other organisms that evolved in non-extremophile environments. In essence, there's a large reservoir of easy-pickins living that generates biodiversity to cross over into extremophile environments.
Now imagine 5x the gravity, 100-1000x the solar irradiance, the lack of magnetic field (and thus direct exposure to solar winds), no atmosphere, or atmosphere entirely composed of a toxic gas, extreme exposure to X-rays, etc. The universe is full of many places where Earth life, even extremophiles, would have no chance of survival. And such places don't have reservoirs of biodiversity from which to adapt to these conditions. They're just dead.
It seems unfathomable to me that life could be composed of bosonic particles, since Pauli exclusion seems to be one of the most important reasons why matter (never mind living organisms!) has the property of spontaneously structuring itself in a rich and complicated way.
> At some point we're either going to murder ourselves or create a Von Neumann machine capable of interstellar flight.
There are many, many possibilities for human futures that are between those two and not do extreme. It is absolutely possible we survive millions of years without interstellar travel or self destruction.
> Since that obviously hasn't happened with alien machines
I also think it is not so obvious that this hasn't happened or isn't happening with alien machines. It certainly could be and we would not know either way. A la 2001: A Space Odyssey, perhaps in fact we are a product of alien machines themselves.
Definitely. In fact, I think they are almost certainly unique in our entire local galaxy cluster, and we will never find anything even close.
We could very well find something interesting, enlightening, sophisticated or using what we might be able to squint and call technology, but I suspect we will never find an alien civilization intentionally broadcasting for example the fibonacci sequence or prime numbers so that we can learn to exchange culture and communicate ideas.
I'm not so sure. We can't even be sure if cetaceans, in particular orcas, have thought patterns similar to ours. Of course, they lack the physicality and environment to develop written history and knowledge and also technology, but we currently have no way of knowing what their thoughts are.
If we focus on recognizable features, we may look for organisms with self-replication skills (a feature of living organisms) and prediction skills (a feature of intelligent organisms).
On the intelligence aspect, the skill to predict the future in general, and imminent threats in particular is useful for structured organisms less resistant than rocks to survive. On that matter I wonder, do unicellular organisms on earth have prediction skills?
What also helped those fragile structures to continue existing along rocks after a long time might be their ability to replicate themselves before being destroyed. Reproductive skills might actually be the first interesting feature to look for in extraterrestrial organized structures.
Sure, but I imagine this is easier said than done. We 21 c. humans would be most likely to recognize as intelligent life something obviously not a natural feature of the landscape, that operates on a time scale under a year and above a split second or so, that predicts that which we can predict, and most importantly has a form corresponding to Earth creatures. Without ticking all those boxes, especially in a truly strange chemical environment, we will have people asserting that they are a complicated chemical processes, but in no sense alive the way we are alive, if we can even recognize them at all.
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Hey, whatever sells a pop science book pounded out over a long weekend.
It's funny how sure everyone was about slowing expansion of the universe and the idea of close rocky planets/distant Jupiters, but only lucky guessers are remembered.
It could simply be that patterns for lifeforms on Earth were set so long ago that everything sort of rhymes. Veer that path at the beginning and you end up with a significantly different answer.
They had a common ancestor of a coral-like sea squirt (If I remember right). That looked nothing like a fish.
Nit: Isn't the estimated age of the universe 14 billion and earth 4.5 billion? I wouldn't call that nothing.
https://en.wikipedia.org/wiki/Future_of_an_expanding_univers...
For example, if life--any life--forms on a planet, it is likely that some macro-organisms will evolve that consume other organisms.
On Earth we have plants that are eaten by animals that are eaten by other animals and so forth and these all act as a form of "battery" in that solar power is converted into energy and increasingly stored in larger "blobs". This is almost necessary for large life to exist. Well, for carnivores at least (eg many whales eat krill and there are a bunch of filter-feeders).
So the chemistry of life elsewhere may be similar or it may be totally different but something like a carnivorous trait is I think almost inevitable.
Once you have that then certain other traits became almost inevitable. Flight, for example. It may be that flight is impossible given local conditions (eg high gravity, atmosphere or the lack thereof). That doesn't mean we'll end up with feathers and birds per se but evolutionary pressure will likely mean available niches are filled. On Earth almost every environment has life, only really excluding the coldest, driest, highest and deepest of places.
Also, consider sensory organs. I expect the ability to detect parts of the EM spectrum, sound, taste/smell and tactile feedback will all likely evolve with sufficient time. And that itself has consequences for what life looks like.
Given the age of our universe, sun, earth and humans:
The probability of some alien life being within say, a range of [-.5 mllion, .5 million] of the life on earth is VERY slim. It is most likely that life out there is either in very early stages (protezoric) or that it is way farther than our current form (how will humanity look like in say, another 500,000 years?, assuming it continues to exist and evolve)Second, you're ignoring the fact that life as we think of it can really only evolve around at least 3rd-generation stars because you need enough heavy elements. That cuts the age of the "life-capable" universe by at least half, so the window of relatively modern life on earth with respect to the age of the life-capable Universe really isn't that small... let's say 350My out of 7Gy, so about 5%.
Evolution has no agenda or goals, other than to select for survival. Most species on this planet have a low intelligence yet are successful, and don't seem to evolve into the direction of intelligence.
The preferred chirality of organic molecules could absolutely have arisen by chance, but it's an interesting to see this in meteorites.
On the unrelated subject of handedness, I saw an interesting thread on Twitter today [1] speaking about how we're starting to synthesize reverse chirality polymers and enzymes, most notably DNA and replication enzymes.
There are a lot of interesting implications.
You can't get rid of L-DNA without reverse DNase, leading to an accumulation of information and transcription. So they need to remake all the enzyme steroisomers.
That alone is interesting, but you can take it further to the limit and produce reverse biology that synthesizes reverse sugars that can't be metabolized by much of extant life [2]. Suddenly a lab-escaped reverse autotroph can out-compete all of us right-handed lifeforms because nothing can eat them. Bacteria, plankton, the entire food web collapses. When we have nothing left to fish or farm, we die too.
Never thought nanotech's grey goo was plausible. Now I see something that rhymes with it, and I could see it happening within our lifetimes.
It'd make a crazy MAD bioweapon on par with or potentially worse than nukes.
Wild tangent, sorry.
[1] https://twitter.com/eigenrobot/status/1420952351968432130
[2] https://twitter.com/prawncis/status/1420982623048925187
The first type is incidental: we've already encountered meteorites from Mars and the Moon, for example, so it's not hard to imagine life bearing material arriving that way.
The second would be intentional: either ET seeds planets or merely visits them with contaminated boots or probes.
Either way, we would pick up some DNA from offworld.
I'd do a life myself, I'd make it post-metallic, post-silicon, post static: I'd make it use water and carbon, so that it can exist everywhere. I would make it so that it can become intelligent on a small time scale, say a few billion years, all on its own, from scratch, on any rock :D
Not saying we have an engineer, but you think of engineered life as you are now as a simple software programmer. But an engineer in 500k years trying to expand more, would probably think of chemical automata that can evolve and adapt in harsh conditions. Say for instance if humanity decided it would be enjoyable for life to exist on Jupiter. It'd have to make something that can try a lot of variations with a very simple first formula to consume whatever gas there is there and survive whatever pressure.
Is there any example that backs this up?
In fact, if we do discover something from another civilization, it is quite reasonable that it would be some sort of Von Neumann probe. It might be made of mechanical parts, "biological" parts, or something in between.
A Von Neumann probe would be highly engineered, and might have no trace of evolution to it.
Except that the very fact that it exists represents many evolved traits. If they are sending probes then their are either curious or expansionist, both evolved traits tied to competition for resources and/or survival. A species totally devoid of any history of evolutionary pressures wouldn't act that way, which is one of many possible great filters: once we have access to the infinite resources of space, perhaps we just stop caring and don't bother expanding. Such logic allows us to learn much simply from the existence of an otherwise silent Von Neumann probe.
But when dealing with infinity, we must appreciate the likelihood of the unlikely too.
Personally, I favor the prospect of the insanely lucky idiot race, that clumsily and completely by chance manage to launch a probe so seemingly sophisticated that every sentient race that discovers it readily submit to its perceived superiority.
Or just a digital clone of a once-biological being that can live for infinity exploring the Universe. Why would you explore the Universe in a meat suit?
Without that, it sounds to me more like hell than heaven.
Maybe we are the Von Neumann probe.
https://memory-alpha.fandom.com/wiki/The_Chase_(episode)
If we were somehow able to segment evolutionary pressures, and normalize their values such that they sum to one, I'd hypothesize that as the average evolutionary pressure goes to zero (meaning high number of evolutionary pressures that are generally uniformly distributed), then this author's hypothesis is true. But as the average evolutionary pressure grows (fewer pressures, or highly skewed distribution of pressures), I imagine it would lead to VERY different looking life. I'd also hypothesize that as the average value increases, it leads to system instability.
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