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Comment by perl4ever | Hacker News Reader

Based on the inverse correlation between star size and frequency, this doesn't surprise me at all.

It seems like there is an obvious further inference to make - people have debated whether life originated on earth or not. Given that the vast majority of planets do not have a star, and given that we know there are chemotrophs even on Earth that prove it is possible to live without a sun, it seems overwhelmingly likely that life came from one of these rogue planets that was large enough to retain enough heat underground for the evolution of life over the first few billion years of the universe. That would also neatly explain why evidence of life appeared so soon after the Earth became solid.

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If you're a fan of Moore's Law and the Singularity, you'll love the reasoning of backtrapolating the exponentially increasing complexity of life over time... to get 0 well before the formation of the earth https://www.technologyreview.com/s/513781/moores-law-and-the...

you mean well before the big bang: e^(a*t) = 0 for t=-infinity

well yes; technically they use one base-pair as the origin of life (which is probably still a little too small).

From looking at the graph, and the 300 milion year doubling, they seem to put life complexity at about 256 base-pairs at the origin of the earth.

There should be a link to the actual paper in the article.

That goes below a discontinuity, 256 base pairs is well below the smallest organism ever observed. A single gene is on average around 10^4 bases, and the simplest organisms have around 10^3 necessary genes. Life below 10^3 base pairs may not evolve at the same speed. It's certainly not safe to talk about it in terms of base pairs, in that era there might not have even been any.

> smallest organism ever observed

...today. Life was simpler back in the day. For example, RNA world. This more primitive life might not survive more sophisticated life. (thougn it's also possible it's still around, but we haven't noticed it; or haven't recognized it as life).

IDK if small enough, but viruses are simpler.

If it can reproduce - e.g. a short strand of DNA or RNA or even something simpler - it could form the beginnings of "life" as a precursor, even though it wouldn't meet our current definitions of "alive".

There's theories of fatty spheres being the first "cells" (really, "kinda sorta cells").

What about Fermi's paradox though? I mean, where is everyone?

It's addressed in the article: it takes a long time for complex life to arise, so we are among - or the - first.

That's the optimistic interpretation. Pessimistic: There's one or more great filters.

No. Assuming this specific paper's thesis, that is the conclusion. There exist other arguments not based on this specific paper's thesis.

Of those, I find plausible the observation that as we tame the world to suit us, we shrink. Cities, civilization, supermarkets, products, TV, internet. By this trend, we'll live in dream terranes before long. (BTW as people get richer, reproduction gets less).

But we'll need power, and eventually a dyson sphere to capture all the sun's light - perfect for an inward-looking, closed-off people! Then what, I'm not sure. Perhaps long before that, we won't need other suns; we'll have artificial suns (controlled fusion).

That's what happens to everyone else: as they grow in technological sophistication, they get better and better at directly meeting their own (previously evolved) needs.

any evidence to support that extraordinary claim?

I think a lot of answers have existed for that question.

In the context of this thread, lets say you are a species which stepped out of your planet, there are plenty of asteroids, and even planets lying around you can mine for resources. You settle billions of your kind in space. You are not running out resources and have no motivation beyond research and science to venture out a little far.

Would you, such a race, want to travel interstellar distances? You would travel far distances by organic growth.

Also its likely how old the universe is anybody who didn't kill themselves to extinction, is likely at our phase of development. And is likely asking the same questions as us. Those beyond our phase of development are hiding for a good reason.

Fermi's paradox is just a hand-waving argument involving tons of unknown probabilities.

It's not a given that alien civilizations "should" have developed this or that technology that we ourselves don't have.

it’s a probabilistic argument, so it is inherently about “should”

Personally I think the answer is anti-natalism. Once life gets more intelligent it takes a relatively short time (compared to the age of the universe) to get to the point where they realise it's unethical to create new life and choose to go extinct.

As a result, intelligent life around the universe only exists as short 'blips', being around for too short a time to ever meet other species.

>it's unethical to create new life and choose to go extinct.

I don't get this. What use are ethics when everyones dead and gone?

The default for unintelligent life is to survive at all cost and fill every niche. You're suggesting that intelligence flips that purpose so that every sentient species eventually becomes depressed suicidal existentialists?

All at the same time, united in a single goal...

Seeing the wide spectrum of intelligence and education that humans manage it's hard for me to believe we'll ever reach a point of uniformity as a species were something like self-imposed extinction would be plausible.

Not depressed or suicidal, just realising they have no right to gamble with another human being's life.

An honestly held belief that their child would have a miserable, depressed, ill life I could understand - especially because those traits can be heritable. I can also understand sour grapes. However the other arguments seem very ill-motivated.

> An honestly held belief that their child would have a miserable, depressed, ill life I could understand

There's always a risk of that, unless you can 100% guarantee this won't happen you're basically gambling with another person's life. I don't think you have the right to do that.

I'd put it even stronger, especially in this context where we contemplate radically simpler origins of life, that mightn't be "alive" by standard definitions (like viruses), and yet are steps along the way to sufficient complexity to be "alive": that life (in this context) is reproduction.

It sounds more like anti-natalism is your personal philosophy, and you make the same assumption the holders of most philosophical, ideological, and religious positions make: sooner or later, everyone else will realize to be true what I realize is true.

The history of man suggests otherwise. The more our civilization progresses, and the more the population swells, the broader the array of philosophical positions those within the civilization tend to hold. We have no evidence for everyone eventually coalescing around one 'right' belief set.

History is also littered with non-reproductive sects, like the Essenes, aesthetics, or, today's answer to these, anti-natalists and child-free individuals. These groups don't tend to be very good at passing their belief systems on to new generations however, as one might expect, and they don't tend to last particularly long once they've emerged on the civilization scene.

Very true. It's very hard for people who don't make children to not just get replaced with people with different beliefs.

Uncontacted tribes in the Amazon likely wonder the same thing. It's such a big Earth, yet only a few hundred humans are known to exist.

Why are there no other detectable signs of human life, like smoke signals, territory markers, or emissaries from any more but a handful of other tribes? Surely if advanced humans existed, they would have contacted these tribes by now, to share technology, discoveries, and medicine. Yet they haven't.

How can the whole planet be so... silent?

If they're not aware of any other humans (let alone all the cities out there) then they're likely not aware of the actual size of the earth. Perhaps they only consider it in terms of the surrounding territory.

I understand the point that we might be too backwards to see the signs of hyper-advanced civilisations, but how is it that _all_ the other civilizations are super advanced to the point that any trace they leave is impossible to understand?

And, won't uncontacted tribes in the amazon have seen airplanes and such?

Uncontacted tribes in the Amazon are not really uncontacted. They are the way they are by preference.

A main component of the paradox is time, but this paper solve that. Life existed from the beginning, but only now has become complex enough.

So, we don't see or hear artificial signs in other galaxies because light is from the times when there was not complex life in the universe.

Now, we only have to solve why we don't see or hear artificial signs in our galaxy. But the problem is not so perplexing because we are talking about one or two million years.

If, for instance, a big part of the galaxy is bad for complex life (after all, we are far away from the center and that could be relevant), Fermi's paradox is solved.

What are the odds that our life is the first that has reached sufficient complexity to be able to communicate within our galaxy? Given that there are 100-400 billion stars (and even more planets) just in the Milky Way: Pretty much zero.

I appreciate a good reason to think deeply as much as the next person ... but odds are just that, odds. If we were the result of some freak black swan event that kickstarted "life", the odds of it happening are irrelevant ... because it did.

To be clear, I'm not saying that's what it is ... the fermi paradox is a great thought experiment. But let's just keep things in perspective. Low odds don't mean something won't happen, just like "true random" doesn't mean the same song can't/won't play 10 times in a row ;)

The troubling thing about the Fermi paradox is that the Great Filter may still be ahead of us.

As in, the universe may be littered with the ruins of single-planet civilizations slightly ahead of our technology level. We may have observed and cataloged many such planets, failing to notice the ruins.

The problem has been always the temporal scales. But if you change that, the odds are not so bad.

If all the civilizations started more or less at the same time that us, it's not so weird that we have not found anybody else. If you add some other factor (maybe civilizations are only possible far from the center, so there is a big spread between them) the probabilities improve.

It also would mean interesting times ahead for humanity.

Of course, all this is only idle speculation.

Never forget to include the Bs term when considering the Drake equation: https://www.xkcd.com/384/

If you look at probability distributions rather than single estimates for every term in the Drake Equation then the absence of visible aliens isn't so unlikely.

http://www.jodrellbank.manchester.ac.uk/media/eps/jodrell-ba...

And just the existence of life doesn't mean there's complex life. We don't have a firm lower bound on how long life took to arise on Earth after we got liquid water on the surface but it can't have been more than 120 million years. Photosynthesis, mitochondria, and other innovations allowing for complex life like you and me took way, way longer. I made a diagram for a blog post here:

http://hopefullyintersting.blogspot.com/2018/03/the-drake-eq...

Three things:

Ordinary Matter ~10^53 kg (4.9%)

  Dark Matter          ~5*10^53 kg                  26.8%

  Dark Energy          ~1.3*10^54 kg                68.3%

 Undiscovered                ?                        ?

We are only made up of < 1/20th of the universe's matter budget, and at that, most of Ordinary Matter is in stars and black-holes (we think). There's not a lot of matter out there (as a percent) left for life to be made of. As for the majority of the budget? Well, we know dark matter falls down ... that's about it right now (kinda). And Dark Energy? Yeah, it makes things fall up. It's ok, makes no sense to anyone else either. I put 'Undiscovered' there, as it seems we are making discoveries about the universe at a pretty rapid rate these last few centuries, so this budget is likely not even close to the real thing.

Also, people talk a lot about not meeting aliens, but just talking to them. Based on the fact that we have little/no idea how Dark Matter and Energy works, and we only really use radio signals (when funding permits), it may be like trying to whisper at the Queen of England while standing in Norway; a telephone would be much better.

2) Tom Scott on immortality and risk : https://www.youtube.com/watch?v=B5a6wrJpxP4

3) Life may be so abundant in the universe that it's not worth talking or meeting up with. What would you say to a single mayfly if you could talk to one on it's level? No scientist or other person has bothered to try, and I think there's a good reason for that.

We are a baby civilization. Everyone is waiting for us to grow up.

I wonder if scientists in the future will ponder how microchips were invented before the steam engine.

"Aliens gave it to them". This puts panspermia in a new light, thank you.

That's exactly why I was on the side of panspermia already. But the number of rogue planets makes a nice independent path to the same conclusion.

An interesting question to me is - if the Earth was seeded with life, does this mean we will find life elsewhere in the solar system, because they were too, or does it mean we will not find life elsewhere, because a rogue planet collided with proto earth in a very unlikely event, and the rest of the solar system (or at least the potential life supporting objects) came out of a sterile nebula around the sun?

I'm not discounting the possibility of life on Earth originating from somewhere other than Earth. However, why would the early conditions of Earth not be sufficient for life to begin over say any other object in space with the base elements for life?

How life began is obviously still an unanswered question, but if the conditions for self replicating molecules were sufficient early on for Earth, I'm not sure why billions of years would be needed for life to form versus several hundred million years.

Earth needed ~ 2 billion years for life to start. Frequent solar winds - especially in the first few billion turbulent years of the universe - basically sterilize planets and the whole 2-billion-year counter gets reset to 0.

Planets that exist without a solar system, but do retain sufficient heat, might have been out of solar winds harm ?

Life on Earth started within a few hundred million years, not 2 billion years.

I'm by no means well informed on these topics, but I'm unsure where you're getting your 2 billion year estimate. Furthermore I thought that Earths magnetic field shielded from solar radiation, and additionally that there's a significant amount of radiation in space anyways.

Further questioning I have though is, does solar radiation penetrate through ocean water?

What radiation is between solar systems or what rogue planets would likely encounter, and how that effects single cell life, amino acids, organic compounds, and any other building blocks to life?

>>Further questioning I have though is, does solar radiation penetrate through ocean water?

Barely. 10km of water will shield you from almost any amount of radiation, and we know of life forms which live at those depths, so they could have developed even when Earth was completely bathed in radiation.

Life appears to have started on Earth remarkably soon after the creation of the planet and the subsequent formation of oceans - ~130 million years by some estimates:

https://en.wikipedia.org/wiki/Abiogenesis#Earliest_biologica...

I generally don't like the assumption that life had to come from space because we don't know how life is created and it appeared so soon in the history of Earth. That is certainly a possibility, but it also possible that creating life from chemistry is easy. Just because we haven't figured it out yet doesn't mean it is hard. Obviously figuring out how it works is hard, but the mysterious mechanism may be simple.

One problem I have with pan-spermia is: Why is there only one tree of life? Not several independent trees. If life evolved in one of the exo-planets, is not possible that several independent forms of life evolved in several planets and some ended up on Earth.

One tree (us) either appeared first and dominated resources, or we wiped our the other trees. Evolutionary forces work at levels above species. Two trees can compete with each other.

If this happened it did so at the microbe level. Physical evidence would be extraordinarily difficult. If we did find evidence of another tree it would be so 'alien' to our tree that might mistakenly call it extraterrestrial.

And since panspermia is necessarily done with microbes, they would get outnumbered and munched by our microbes if they arrived after our tree dominated our planet. Unless other planets happened to give birth to hardier, more virulent microbes, then welcome Andromeda Strain.

The individual nucleobases (cytosine [C], guanine [G], adenine [A] or thymine [T]) are made from the 4 most common elements, and appear to be modestly simple molecules. Is it so unbelievable that they naturally occur like methane or sodium glass?

I also don't subscribe to panspermia because first local origin must be reasonably proved unfeasible, but playing devil's advocate ¿what if our life tree outcompeted the others?

That's certainly possible, but not likely. Life began on Earth almost as soon as it was cool enough to do so, so we would expect to see life pop up over and over again. And it's highly unlikely that they would all get wiped out.

> life appeared so soon after the Earth became solid

It took hundreds of millions of years, possibly up to a billion years, for basic life to form on Earth. I would say that is not "soon"; it's a really long time.

The obvious response to that is, yes it seems like a long time, but it's not much on geological time scales. But it feels to me that there's an implicit circular argument here: the whole reason that geological time is measured in terms of such huge spans is because it took life such a vast amount of time to get to the point where humans exist to discuss it (understandably).

But that's mostly because humans aren't an achievement of "life". We were never a development goal of "life" nor does the universe care very much about us - even if we built megastructures directly harnessing the energy of black holes and stars.

If current knowledge is remotely correct, heat death will happen, no matter how immortal Homo deus will become. The quarks are against us.

And if complex systems theory teaches us anything then it would be preposterous to assume any ultimate superiority in understanding the universe on our part.

Who knows who wrote crazy alien versions of Hacker News posts 2 billion years ago in one of the other couple of thousands of galaxies seen in Hubble Deep Field alone...

Humans are really just an example, I regret mentioning it. All significant developments in life (e.g. multi-cellular lifeforms, post-Cumbrian explosian animals) took hundreds of millions to billions of years.

In fact given the fact evolution is a process without a goal. Intelligence could be even more rare among multicellular lifeforms.

Or the consequence of great intelligence is an evolutionary dead end. What if intelligent life becomes smart enough to destroy itself, but doesn't survive quite long enough to use that intelligence to save itself.

I remember reading that 4 or 5 intelligent hominids coexisted in Africa a million years ago. More or less intelligent. It can't be that rare then.

In fact, dolphins. Octopi. Yeah, pretty much a given I'd imagine, in the right complex ecosystem, that intelligence is a thing.

Life shows up in the fossil record more or less as soon as rocks on the Earths surface start forming.

The first billions years on earth mostly involved the planet getting hit by large things and the surface melting. Repeat every millennium.

You just explained why there's no fossil record from early earth, unless I'm misunderstanding you and that was your point.

Ocean floor is continuously destroyed as it's subducted, and continents won't have fossils if they are under frequent bombardment.

> continents won't have fossils if they are under frequent bombardment.

Right, but if giant bombardments completely boil away the oceans and atmosphere to rain liquid rocks back down on the surface, there very very likely won't be life, either. So the claim is not just that "fossils only go back to X" but that X is so close to the end of the giant bombardments that there's almost no time left (geologically speaking - maybe 10-20MY) for "life but no fossils yet".

> It took hundreds of millions of years, possibly up to a billion years, for basic life to form on Earth.

This is a common popular misconception. See something like Simon Conway Morris's book Life's Solution. There is evidence that life existed on earth almost as soon (geologically speaking) as the early bombardment stopped repeatedly boiling away the entire oceans and atmosphere, within something like 10-20 million years. Thus, all the interpretation about the implications of that.

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