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Comment by hinkley | Hacker News Reader

We are on such a Goldilocks planet it isn’t even funny. Or life is so exquisitely tuned to optimize for earth’s conditions it isn’t even funny. Or both.

We see magnetic fields this strong on gas giants, but not on inner planets. I wonder too if we will find that some asteroid impacts and the formation of the moon didn’t goose up the magnetic flux of the core while they were at it. Maybe habitable zones only appear on tortured worlds, like earth and some of the moons of a Jupiter, because normal planets are just too boring, don’t have enough building blocks for life.

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“Or life is so exquisitely tuned to optimize for earth’s conditions”

That’s how it works. Life adapts to the conditions it faces or it goes extinct.

It took billions of years to get to that point, too. Complex life only really got going during the Cambrian explosion.

It took billions of years, but not so much of evolution itself but rather of saturating the entire atmosphere with oxygen, which was monumental work given they only had that much sunlight at the surface. Life has its limits (what doesn’t) but is very quick in a geological sense. Sadly there is not much time left for it.

Probably true, but as a balance for this there are about 100 billion galaxies in the visible universe each with about a hundred billion stars, each with a chance to build up the right conditions for live.

That's 10^22 opportunities to get it right. We can't possibly be alone.

1 in 10^22 sounds like a lot but it really isn't when it comes to probabilities. It's only about a 10 sigma evidence against a null hypothesis.

Put it another away, all it takes is about four one-in-a-million chance independent events (or filters) and you're left with Earth being the only planet with life in the observable universe.

>Put it another away, all it takes is about four one-in-a-million chance independent events (or filters) and you're left with Earth being the only planet with life in the observable universe.

This presupposes life can only exist on a planet with several exact characteristics that we have on Earth. Given life on Earth exists quite nearly in every environment that exists, it could be expected that despite significant filters, there is room for several variations which enable life even if quite different.

The real question to me is if intelligent life exists.

If you look at the history of earth, there have been several filters that very nearly wiped out intelligent life.

Further, we needed a few extinction events just to have a world where our intelligent life could reach the point of developing science. We wouldn't, for example, have been able to thrive in the Jurassic period. There were simply far too many predators to keep us from doing anything more than hiding in caves and trees.

Then if you look at the evolution of humanity, we very nearly went extinct a couple of times. We were estimated to have been whittled down to 10000 citizens at one point. [1]

Evolution, it seems, doesn't necessarily select for intelligence. It selects for better killers and better hiders. Being smarter than the predators doesn't immediately grant enough benefit. If it did, we'd probably not be the only intelligent species to ever exist.

[1] https://www.npr.org/sections/krulwich/2012/10/22/163397584/h...

This is why I worry about our potential extinction: what if we truly are the only beings in the entire universe capable of exploring it, and we wipe ourselves out?

What an incredible waste.

How is that a waste? The universe doesn’t exist to be explored. It just is. It is not wasted if it is never explored.

I like to think of the universe as a large mass of hydrogen that evolved to consider itself.

Science fiction idea: a “universe” is actually an egg, a race of godlike beings’ method of reproduction and we’re the embryo. When consciousness grows to encompass the entire infinite extent with every particle contributing, it hatches.

This is the exact point that I would love to see someone really dig into relative to some of the prevailing theories of biogenesis. Molecular biology is so mind-bogglingly complex that 10^22 planets could disappear into the noise floor very quickly.

Now justify your implicit assumption that the chance life arises on a suitable planet is at least 1 in 10^22.

It is at least 1 in 10^22 because we have very strong evidence of one habitable planet

Edit: See https://en.m.wikipedia.org/wiki/Earth

The chance of a habitable planet happening could just as easily be 1 in 10^10000000000000000000000000, and it was just a freak occurrence it happened at all. Just because something happened once doesn't tell you much about the odds of it occurring.

Why 10^22, and not 10^10, or 10^40, or whatever? The number has to come from somewhere. This should be a strong clue your logic is defective.

This earth place sounds preposterous!

I'm supposed to believe the planet's alpha predators willing make themselves subservient to smaller, but more furry beta predators?

Anything goes, when you're made of meat :-)

Wait...are you asking me to believe in thinking meat!?

To be fair, we are working very hard on changing it to uninhabitable

>uninhabitable

*for humans

If you get hit by a bus on a second crosswalk that doesn’t mean the chance of it was 50%.

The point is we don’t know either way. Earth may or may not be a “Goldilocks” planet.

Also, the numbers above are based on the observable universe. We have no idea how big the universe is outside that region. It could be infinitely large.

Right. So, the argument "10^22 is a lot so we can't be alone" is a non sequitur.

I understand it to be a counterargument to the “Goldilocks” non-sequitur.

A root fact of my philosophy is the unrefutable claim that I exist, and am alive, so the 1 in 10^22 seems very reasonable.

Not 1 in 10^21, or 1 in 10^23? Where exactly is this number coming from? You are implicitly assuming a probability that life can arise. Don't you think that number has to be informed by an actual theory of how life arises, not inferred just from your own existence?

And in fact, you can conclude nothing from your own existence. Observer selection bias.

What an oddly pedantic comment.

10^21, 10^22 and 10^23... Whichever number, the point that the parent poster was making doesn't change at all.

>You are implicitly assuming a probability that life can arise.

What are you suggesting? We're all actually not alive? Come on.

No, it's not oddly pedantic. It's more an expression of anger, because this sort of argument is common among SETI people. It's a very common error: there's lots of opportunities for life to arise, therefore life must be common in the universe. And this is utter bullshit. Probability does not work that way!

> there's lots of opportunities for life to arise, therefore life must be common in the universe. And this is utter bullshit.

Why anger? And will you expand on why this is utter bullshit? In what way does probability not work this way? You are making strong assertions without expanding on why you believe those assertions.

Your assertion also goes against some pretty big names in the field; not that big names are automatically trustworthy, but they do seem to carry more weight than a random HN comment (no offense).

The argument that gets my goat is basically this: "if N is large enough, then for any probability p > 0, N p > 1." And that's clearly false.

The SETI people making this busted argument are implicitly assuming p, the chance that life arises on a suitable world, is not "too small". And there is no basis for making that assumption.

I don't think the common form of argument is that because N is large enough, life must exist.

The argument is generally that scale and probability favor the existence of intelligent life, assuming Earth is not somehow exceptional in the universe.

Assuming Earth is exceptional seems just as problematic.

Welcome to the Fermi paradox.

And for any N, if p is small enough, other life is very unlikely to exist.

Why are you holding p fixed and allowing N to increase? You are implicitly assuming N is in that regime where N > 1/p. That's just assuming p > 1/N, and there's no good reason to make that assumption.

I sympathize -- I've argued your side of this many times. I won't jump in today, but I just wanted you to know your words aren't falling on entirely deaf ears.

I think observer selection falls into a cognitive blind spot many people have.

This fallacy has always bothered me so thank you for stating it so well!

> I don't think the common form of argument is that because N is large enough, life must exist.

The comment that started this thread: "That's 10^22 opportunities to get it right. We can't possibly be alone."

On all of the Goldilocks planets we have so far been able to image with the resolution needed to determine the presence of life, we have determined the presence of life.

That is not mathematically rigorous, but it is, from the Bayesian perspective, enough to move the needle.

Observer selection bias blows that argument out of the water. Ask yourself: if life were extremely rare, what would be different here on Earth? Nothing, because life has to have started on Earth for us to be here to be thinking about it.

> That is not mathematically rigorous, but it is, from the Bayesian perspective, enough to move the needle.

That is obviously false; zero observations will never cause a Bayesian adjustment.

As far as N is smaller than the available combinations, the hypothesis is probable.

This thread comes across as bickering, and detracts from OP's original euphoric "wow" message.

Orthogonal and bickering, but I find it interesting. I can keep two thoughts going at once. Sort of.

How much subjective time would it take to visit say, 1/10th of those galaxies, if you were traveling at say, 99% of the speed of light?

It seems to me that the odds of encountering other life forms are vanishingly small, simply because of the scale of the universe, combined with the low odds of finding other life forms. Sure, it might happen, but we're alone until we're not. And we're incredibly likely to remain alone for a very long time.

“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.”

For some reason I'm inspired to write:

Time is short. You cannot imagine how vanishingly, briefly, disappointingly short it is. I mean, you might think you have all the time in the world, but to the universe, you're a fraction of a gnat's wingbeat.

Why do we want contact? Leave these trees of life discrete. We deal with terrestrial invasive species enough ravaging our ecosystems. Imagine if we let loose some organism that is capable of outcompeting all other life on earth? It's happened before. The early history of life on earth is an assortment of dead ends out competed by the few who emerged from the primordial soup that beat the less fit forms for finite resources. We've lost a lot of variation along the way; we have regulatory processes that are conserved from humans to yeast because we all come from a common lineage. We are all a small part of the earth planetary meta organism. Introducing external life into that system may simply lead to quick extinction of that external life at the place its been introduced, but the worst possible case scenario is that life takes root, is more fit than existing forms, and displaces the planetary meta organism we currently are components of.

> The early history of life on earth is an assortment of dead ends out competed by the few who emerged from the primordial soup that beat the less fit forms for finite resources.

I’m not sure how true that is, and reflects a somewhat older view. There was a lot of cooperation involved, particularly in regards to symbiogensis, which the older generation still opposes.

https://en.wikipedia.org/wiki/Symbiogenesis

> In her 1981 work Symbiosis in Cell Evolution [Margulis] argued that eukaryotic cells originated as communities of interacting entities, including endosymbiotic spirochaetes that developed into eukaryotic flagella and cilia. This last idea has not received much acceptance, because flagella lack DNA and do not show ultrastructural similarities to bacteria or to archaea (see also: Evolution of flagella and Prokaryotic cytoskeleton). According to Margulis and Dorion Sagan, "Life did not take over the globe by combat, but by networking"…

https://en.wikipedia.org/wiki/Great_Oxidation_Event

This is what I am talking about. This perhaps predates even symbiogenesis or perhaps drove it. Anaerobic lineages died out in the oxygen rich environment that the first forms of photosynthetic life created. Cellular respiration using oxygen, as animals do, probably evolved after the atmosphere was already oxygen rich. There is a huge fitness advantage if you cannot make use of light energy, but can absorb cells that can and maintain them as photosynthetic eukaryotes do today through symbiosis of the cyanobacteria that became cloroplasts.

What I like about this example are the parallels to modern times. The great oxidation event was an extinction event brought on not by external factors, but by a life form producing gas that changes the composition of the atmosphere and leads to dramatic effects across the planet. Not unlike us humans today with our CO2 production.

How long until a post-human consciousness will have a lifespan of a billion years?

If never, why is that not a possible future?

There's two scales you can change, yourself, and the tools you use to interact. So how fast can you make a spaceship competes with how long you can make your life.

Post human conciousness on earth has already been around for what nearly 4 billion years? Life on earth represents a meta organism. It's a human bias to elevate the significance of the human species component above that of the greater meta organism. Ecology can be studied with similar tooling whether the frame of reference is a continent or your gut microbiome. If we wanted to, say, ship earthbound life to another planet, then lets consider the best form of earthbound life to make that journey across a hostile environment for an indefinite period of time. Chances are its not humans adapted to persistent hunting and gathering, but put some microbes or spores into a vial wrapped in gold foil, and you wouldn't even need a complex generational space ship to seed earthbound life across the universe, just a gun capable of firing the vial on a vector.

You and I are using different definitions for “post” and “conscious”, not sure how to move forward with such differences.

If you could travel with constant acceleration you could get very far very fast.

Traveling with a 1G acceleration for a 100 years could take you to the edge of the universe, though billions of years would pass on earth.

https://en.wikipedia.org/wiki/Space_travel_under_constant_ac...

You're just referring to known opportunities. The fun starts with unknown chances and specifically infinities. If time is infinite, anything that can happen eventually will happen, right here. If space extends infinitely beyond the observable universe, anything that can happen is happening somewhere (an infinite number of somewheres) right now. No, people approach this question from a far more skeptical position than they should.

> If time is infinite, anything that can happen eventually will happen

This doesn't come close to being true. That just isn't how infinite quantities work. You can have an infinite sequence of numbers that doesn't include 3 at any point.

The observable universe isn’t particularly interesting as far as looking for life goes, heck anything outside of our immediate intra-galactic neighborhood isn’t particularly interesting because we have no chance in hell of ever visiting or communicating with systems more than a few light years away.

So how rare are true earth like planets does matter a lot.

Undoubtably true, but we may never know for sure since light speed limitations means we will never leave our galaxy (and probably will never personally travel beyond our solar system) and there might not be any other life in our galaxy.

time slows down as speed increases, so in theory, it may be possible, for the traveller to leave? (Although the observers would be long gone on the return journey. Relativity is a crazy thing)

Sure, but that only matters when you get up to a fairly high percentage of light speed. We’ve never even approached 1% of light speed. The fastest space craft is NASA’s Parker Solar Probe. It has reached 0.05% of light speed.

These are engineering limitations, not "light speed limitations"

It’s both. Even if we could engineer a drive to go a high percentage of light speed, it still takes forever to get anywhere. Space is really really vast and even light speed is really really slow. FTL travel is the only practical solution, except current physics says it is impossible.

Well, there are a couple of problems with this conclusion. One is that it assumes that those 10^22 opportunities are evenly distributed in time and space. Another is that we might not be alone, but we might also never meet our neighbors.

The universe hasn't always been a habitable place. It's been hotter and more chaotic; life may have arisen and become extinct due to radiation or cosmic-scale collisions a billion times on a million worlds over the universe's early history. We don't know exactly where the lines are, but we're fairly certain at this point that the universe is not static in time and it has had a less habitable period and will probably have a less habitable period again.

We also don't know what the prospects are for long-term life in environments like galactic cores. Of the hundred billion galaxies we've observed so far, maybe only the tiniest fraction of them are capable of supporting life in the long term -- recall, it has taken Earth 4.5 billion years to produce us! -- and of those that are capable of supporting life, perhaps they can only support life out on their edges.

These amount to some pretty significant polynomials added to the Drake Equation, and they can attenuate the result a lot.

But let's imagine the AI swarm, the most popular rebuttal to the unforgiving conditions of time and space. Let's imagine that one arose a billion years ago, and it happened right next door in cosmological terms -- 1000 light years away. Let's forgive that we are now 71 light years farther away from it than we were when it arose [1], it's fun to mention but a rounding error in this imaginary scenario. You still have the incredible problem of maintaining a homogeneous density of AIs over a rapidly increasing volume! Let's figure one lonely AI to a solar system's worth of space in 1000 light years in every direction -- that works out to 2.6 trillion little self-sustaining devices! [2] With "only" a billion years available to cover that volume, 2,600 new AIs have had to come online every single year (on average) and somehow teleport to their proper location. On Earth, it's easy for us to manufacture 2,600 pieces of complicated electronics in a year -- all it takes is the collective efforts of millions of people to mine the raw materials, refine them, design components, manufacture them, and ship all those molecules back and forth across the globe some absurd number of times. In space, this is much harder.

And this is, I think, a very generous treatment of the AI swarm thought experiment. It assumes that each node has an indefinite lifespan, and both communication and travel are somehow instantaneous over great distances, and that all of the necessary raw materials are always nearby, and that the entire thing never goes to war against itself, and that there are no cosmological disasters (like a GRB) over that billion year span, and that it all happened right next door to us in our very own galaxy. This is the best case scenario for an extraterrestrial presence in our solar system!

[1]: Approximation of the universe's rate of expansion * 1 billion years * 1000 light years of distance, https://www.wolframalpha.com/input?i=70+km%2Fs%2FMpc+*+1000l...

[2]: Volume of a sphere 1000 ly in radius * astronomical units per light year / 100 AU, https://www.wolframalpha.com/input?i=%284*pi*1000%5E3%29%2F3...

> It assumes...

It also assumes a level of technological sophistication not too different from our own, depending on advances in AI and automation this could feasibly be us in 200 years. We hobble ourselves by only considering an alien species to be somewhat more advanced than us, it's a forgivable fault because we want to keep things realistic but it prevents us from asking the harder questions about what would be possible in 1,000 years or 1,000,000 years of continued technological development. Kardashev dared to dream when he proposed his scale. What if we could convert our entire solar system including the sun into usable energy? an entire galaxy? It's akin to the hunter gatherer asking "what if we could harness the power of lightning?" he may be very far from that dream becoming a reality but it did eventually give way to man's ingenuity. We should ask those questions: What if we could control gravity? What if we could move faster than light? What if we could create any kind of matter or field from scratch out of the raw stuff of spacetime? What is beyond space itself and could we ever access it? Dreams maybe, for today at least but perhaps not forever.

>Or life is so exquisitely tuned to optimize for earth’s conditions it isn’t even funny.

Well, of course Earth life is optimized for Earth's environment. Otherwise it wouldn't exist.

I bet somewhere out there an intelligent lifeform with radically different chemistry and biology is posting on their online forums, "It's pretty amazing our planet has exactly the liquid argon-cadmium oceans we need to survive, really makes you think."

It's really hard to imagine chemistry that could support non-carbon-based life. You just really need an atom that can make 4 covalent bonds.

Silicon can make 6 covalent bonds (I think; it’s been a while since I’ve taken any formal chemistry/material science courses).

If we see life as an energetic process (movement of energy across membranes) then it makes sense that it happened here on a planet with an active tectonic situation and plenty of energy differentials -- and yet not so intense that they'd be destructive to emergent life.

I like Nick Lane's description of abiogensis as a process born in the chemical reactions at early alkaline hydrothermal vents. Again, a process that could only happen on a very specific kind of planet with active tectonics combined with a (at the time acidic) liquid water ocean.

But that would be the majority of rocky planets with water, no?

Seems like most are expected to be tidally locked, or without active tectonics.

> Or life is so exquisitely tuned to optimize for earth’s conditions

It seems that it would have to be. If a planet has had life for a large number of generations, that life will have evolved to fit the conditions.

> We are on such a Goldilocks planet it isn’t even funny.

If we are the only living planet then it is out duty to life on this planet to expand outwards.

If not then it is our duty to meet the others.

Life here will eventually die regardless of what we do. We should start working on spreading the seeds as far as possible. Otherwise we would have lived for nothing as a species.

Why do we have a "duty?"

We haven't even figured out how to be good to each other. That's far more important than worrying about how to get a civilization on Mars. If most people die, that's a tragedy. If everyone dies, that's nature and no real value is lost.

It is our duty because life is programmed to spread. It’s in the biology of any living thing, ranging from animals to plants to microorganisms. Our planet’s lifespan and size are finite so we have to seek out new venues.

You are right re being good to each other.

Scarcity of resources leads to a lot of bad things. People and all life are programmed to compete for resources in order to survive. Most wars are caused by the struggle to control these resources. And that causes misery to those on the losing side.

Near space has endless amounts of everything we need so that competition can be more relaxed.

If anything, expanding to space will make life better here on earth, by keeping our planet cleaner and safer, and will give us the time we need to learn how to move beyond our basic instincts. We progressed a lot but we need to do more.

Mars shouldn't even be the immediate goal. We should harness the energy of our star at its full potential and extract nearby resources as first steps. Mars will be a byproduct of these two.

Else we are stuck arguing over -isms and tribal wars at scale over who owns what part of the planet.

The very fact that we push electrons writing here shows that we humans have moved beyond the natural, so simply stating that “that's nature and no real value is lost” is not in our … nature.

I don't know, it seems as though one of the basic instincts we've progressed past is our instinct to spread. When given the freedom to choose, people reproduce at less than a replacement rate. World population is still rising, but birth rates are falling nearly everywhere as different regions become more prosperous. Assuming this continues, where will we find the people to spread across the universe? Japan can't find people to spread outside of Tokyo.

I am not convinced many people are free to chose, particularly in the west. When your life depends on a mortgage, ever increasing bills and being in an office at least eight hours a day you dont have much of a choice. Thats just fancy poverty.

People with actual freedom seem to reproduce beyond replacement rates:

https://www.statista.com/statistics/299077/billionaires-chil...

https://qz.com/1125805/the-reason-the-richest-women-in-the-u...

Billionaires are not a good model for what people will do if they don't have to worry about mortgages and bills, they're a model of what people will do when they have virtually no resource constraints whatsoever. If people don't have to cook, clean, give up vacations, sacrifice their hobbies and career goals, and can pay an army of servants to do any unpleasant childcare tasks, then yeah, I suppose they'll have more kids.

From what I've read a certain number of people do say that financial constraints cause them to have fewer children than they'd like, but stated preferences are not far enough above revealed preferences for that to change the result. In Hungary Orban is virtually throwing money at people to have more kids but the population is still declining. Countries with robust social safety nets are doing no better than those without. The only exception I'm aware of is Israel, primarily due to the Orthodox community.

> We haven't even figured out how to be good to each other

Having explored this question for a long time, I think we have figured it out, quite a long time ago, actually. But the answer is very difficult to accept. Huxley recognized this, and used the answer to show how it could be used to both create a dystopia ("Brave New World") and a utopia ("Island").

>life is so exquisitely tuned to optimize for Earth’s conditions

*life on Earth

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