How does this change our outlook if one assumes The Great Filter hypothesis? Does this lower or increase that such a filter would be behind us or before us?
Yes, life could be very improbable to appear, but there is a counterargument to this hypothesis: on our planet, life appeared almost immediately once the crust solidified and oceans appeared.
If there had been a 3 billion years period, there may have been an argument that maybe we got very lucky it appeared at all, but we have fossils that are just 100 mil years younger than the apparition of oceans. And we keep finding older ones.
If life was a really rare occurrence that would mean we would have been lucky twice: that it appeared at all and that it appeared that early.
> Does this lower or increase that such a filter would be behind us or before us?
When so many things are unknown, it makes little sense to talk about probabilities. It removes a possibility for a filter behind us.
I still have doubts that evolution necessary leads to intelligent life. When I started getting interested into evolution, my main surprise was that there is no "optimal" unicellular life-form. Why isn't the earth covered by a green pellicule of photosynthesis-able cells that would be a Kardashev I organism without ever reaching intelligence?
I still don't understand why it did not happen. Evolution favored competition to optimality and the reasons are unclear. I would not be surprised that evolution in other ecosystems would result in one organism "winning" over all the others.
My personal opinion is that we will find a lot of life on other planets, but many will be unicellular and many will show an evolutionary process that is stuck in a dead-end.
I expect intelligent life to be rare, and that the "great filter" is that we will find things much more worthy of our time and energy than colonizing the universe or doing mega-engineering projects. Maybe we'll colonize a few star, build a Dyson star or two, but then we will discover that everyone prefers to spend time in another dimension, or in infinite pocket-universes. Maybe the real party is inside the black holes or the neutron stars and all the advanced civilizations are waiting for us to figure it out.
The idea that an intelligent species would colonize the universe assumes that it does not manage to handle its demography or views its growth as a good thing. I doubt that this is a rational conclusion once you reached the state of full automation.
Nature does not care if energy of sun is used optimally or not. It just cares if offsprings live or not.
If you reach a point where one organism developed enough mechanisms to resist simple predators and that their advanced predators die out, I think it would be impossible for evolution to get out of that dead end. I am not sure that getting unstuck is a universal feature of life.
Emergence of sexual reproduction, of multi-cellular organisms, are all very weird phenomenon that I think are risky to take for granted.
I mean, it feels like playing Conway's game of life: Often, when you start a random one, it all dies out. It often gets stuck in a position where just a few things vibrates. Some last longer. Others go on forever but are rarer.
My intuition (which can be dismissed without argument) is that life is similar: if the conditions are right, it may lead to emergent evolutionary behaviors that eventually can lead to intelligent life, but that's not the most common outcome.
Evolution works on the level of individuals. Even if you end up in a situation where you have only clones of a single organism populating whole planet, these clones will compete with each other. Because of different environmental conditions, random mutations and distances this super successful organism most likely will still undergo speciation.
If you have ever played with evolutionary algorithm, you have seen that it is very easy for a system to just "win".
Want to optimize a thing that heavily depends on a mass/surface ratio? Oh, a sphere is the perfect solution. Evolution can't beat it.
Yes, maybe there can be various colonies of photosynthetic organisms competing over millionth of percents of efficiency for billions of years. That's what I call a dead end of evolution.
> Yes, maybe there can be various colonies of photosynthetic organisms competing over millionth of percents of efficiency for billions of years. That's what I call a dead end of evolution.
I would call that a plateau, because that was the state of Earth for about one or two billion years.
I think overall we agree - transition from single cell life to current level of complexity is not an easy one. We are significantly more likely to find single cell life in the universe, than anything that would resemble animals.
But you should also remember that Earth was not uniform in space and time, photosynthesis does not work equally well everywhere and overall conditions change a lot over millions of years. So even single cell life will be damn complex and dynamic on a scale of planet and evolution.
If all the predators died out, then those defense mechanisms would become wasteful, and organisms that didn't have those defense mechanisms would be more efficient. That would open the door to the development of new predators. The situation you're describing is not a true equilibrium, in other words.
The fewer predators there are, the more wasteful defense mechanisms are, and therefore the more disfavored they are by natural selection. The more predators there are, the more defense mechanisms are favored. The equilibrium is neither zero defenses nor 100% effective defenses against predation. It's somewhere in-between.
The predators get to evolve too, by the way. There's no 100% effective defense against all forms of predation.
Take your shell example: The shell is made out of something, presumably abundant. If it becomes less abundant this species becomes vulnerable again.
What if the substance is abundant? I suspect (here again, just an intuition) that our planet is actually exceptionally good, not for life to appear, but for evolution to occur.
One theory of abiogenesis supposes that life started in hydrothermal vents, in conditions that are very far from what is considered "habitable" for the current life (very hot water, high pressure and, IIRC hard acidity)
Maybe these are the only conditions for life to start, but does not offer a lot of room for improvement. Maybe there is just so much things you can do to efficiently colonize interstices of volcanic rocks. But then you have a whole host of conditions offered to you: a gradient of temperatures and pressures, light, storms, changing currents, varied geology. And then later on, dry lands, of a varied range of temperatures.
If the conditions for abiogenesis and evolution to occur are very different, Earth could be unique in that aspect: how many oceanic planets on a stable orbit will still have days, tides, seasons, storms AND hydrothermal vents of the correct type to generate life?
tl;dr: It is possible for both of the following statements to be true at the same time:
(1) The Drake equation gives a true estimate for the mean amount of extant civilizations in the galaxy, and that estimate is relatively large. (As in, much greater than one.)
(2) The probability of sentient life existing outside our solar system is infinitesimally small.
The reason for this is that the Drake equation gives a mean over all possible universes, with the solution space created by our uncertainty in the parameters. Since all of the parameters have more uncertainty in one direction than the other, the probability distribution is not symmetrical, and so the mean, mode and median are not the same. In fact, it turns out that when you do the math right, you find that essentially all of the probability mass in the Drake equation comes from the cases where almost every star has a civilization around it. Using our current best estimate numbers, and excluding the cases we can conclusively disprove because we are not already chatting with our neighbors at Proxima Centauri, P(we are alone in the galaxy) > 50%, and P(we are alone in the observable universe) > 39%.
We don't even know all the steps between "Step 8: Where we are" and "Step 9: Colonization." Maybe a moon is required for it. Maybe materials not found on this earth are required for it.
I think we as a species have decided that colonizing Mars is possible. It might not be probable, but we can do it. We know how, we just haven't yet.
Humans just might be the first intelligent life. If the Milky Way was already colonized, some civilization made the first leap to another planet.
It's manifest destiny. We have to colonize the universe. It's our moral duty as an intelligent species to maintain awareness of the universe.
If there's no great filter before our current stage, then it's extremely unlikely that we're the first intelligent life in galaxy, and either there's a great filter after that or many civilizations have risen already (and have had more than enough time to colonize the whole galaxy a thousand times over at a relaxed, leisurely slow pace, if any of these civilizations wanted to) but we just don't see them for some reason.
To make that point perhaps more clearly, let's say that before and including us, our galaxy has had X planets like Earth. Whatever that X is (1 or 1000 or billions), the total number of such planets that our galaxy will ever have is less than 2X. That doesn't rely on any poorly understood theories, that doesn't rely on any aspects of how life or intelligence might form - the lifecycle of stars is well understood, the age of universe is well understood, and the future has less new stars and planets than the past; we're currently past the midpoint of star/planet forming and that's that, most of the planets that will ever exist in our galaxy either exist right now (most of them for longer than Earth) or are gone already.
So whatever the "dice" of a suitable planet existing and creating intelligent life are - if we're the first ones (and I'm not making a point whether we are or aren't, whether that's likely or not, that "if" is an assumption), if X rolls of dice resulted in just a single success - then the remaining less than X rolls simply won't suddenly roll a hundred more successes; if the total number of spawned civilizations until us is 1, then that means that the total number of spawned civilizations until end of the universe would be 1 or 2 - and if it's 2, then it would be a hit-by-a-lightning-while-typing-this level of coincidence is that second one happened to arise at the same insignificantly tiny moment in time that constitutes the existence of homo sapiens until now, just some tiny 100 000 years after us instead of some 10 000 000 or much more years after us.
OR, possibly, there are and will be much more civilizations than that - but then some of them have been long before us.
Mmhh.. not so sure you can conclude this. You assume all rolls of the dice are identical (same likeliness of all outcomes), but this ignores the fact that the universe is ever-changing from a particular state towards its inevitable fate.
Consider for instance the "pulse" of galaxies as they collide and 'ignite' their central quasars anew — this coincides with extremely harsh local conditions for said galaxy merger, which becomes likely very unhospitable to life. Conversely, when the jets calm down (mature) and winds recede, star formation kicks back up and a new galactic cycle begins until the next merger (if ever).
This mechanism alone could paint a very asymmetric past and future set of conditions (relatively to our rather 'calm' present, but it's actually a cycle). Some of these conditions would definitely affect life (for instance, during its active phase, we suspect that a galaxy's quasar might be strong enough to blow away planets atmospheres).
There's just too many unknowns at this point. Drake's famous equation was actually meant to expose this fact (he actually knew it was flawed/impossible to solve, but felt it was a meaningful thought experiment, iirc).
But our galaxy and solar system is relatively young compared to the universe. Plus the universe is massive. There's approximately 10 billion galaxies in the observable universe with and average of 100 billion stars per galaxy. At that scale the processes that created life on Earth would have happened countless times before. The building blocks for life are common in the universe but weren't common on the early, inhospitable Earth. It was brought to our planet from comets which is where the Earth's water came from.
Combine that with:
* The fact that life on Earth was possibly dependent on life from other planets to form.
* Has had multiple near-total extinction events during it's time.
* We're outright dependant on fossil fuels left over from previous cycles in order to get to where we are now.
* Our own species have been close to extinction multiple times far before we reached our current technological level.
* Our own emissions most likely blends with the background noise and are probably not detectable that far out.
* It's taken us countless millennia just to get to the point where we're approaching a technology level that will allow a fraction of our population to scan parts of our closest galactic neighbourhood for disproportionately large signal sources that happens to be on the bands we find to be most convenient.
To me, it sounds like it's quite plausible that we could be amongst the first to spread on an interplanetary scale (assuming we actually manage to do that), or that something happens and we go back to pre-industrial levels, leaving the aliens on the next habitable planet wondering why the level of noise from group of stars a few hundred light-years away suddenly grew quieter.
Interesting justification for colonising the universe. If you were from another civilisation, more advanced, you could see humans as a bunch of parasites taking over planets and destroying other life and themselves in the process.
This grand justification of maintaining the awareness of the universe is a bit of a stretch.
But I guess it would make us an "advanced" civilization.
Which is to say nothing of the riches that await us if we can solve orbital and deep space access problems. If you can get to Mars, you can get to a bunch of asteroids with enough gold and platinum to ensure only the rich will have things made of wood.
I thought space flight is too expensive and unobtanium is yet to be discovered?
Further, even if a group manages to secure trillions of tons of common materials for us today, who's to say it will be given out for free? If it is, well, maybe I want you to give my country a bit more of the share than other countries, or I'll take their share by force. Even if we emerge a united world after something like that, we may find that we've developed far superior technology that has no use for the materials you've acquired.
There are tons of real-world questions that have to be answered, and it doesn't matter if we don't have time to come up with a good one, because someone will pull the trigger first.
The idea that all problems must be solved in some order is naive. There is no order. We don't know what the correct path to future desired social outcomes is, we have what seems to be within reach and we achieve it.
A few hundred years ago and you would have priests declaring the men who spend their leisure playing with wires and magnets, or looking at tiny things through looking glasses are wasting their time - clearly they should be working on getting more blankets and clean air to those suffering from disease!
That doesn’t necessarily follow. In fact one could imagine that earthly problems will provide the stressors to spur us into action.
Lengthy as they are, Kim Stanley Robinson’s Mars trilogy novels are so interesting for challenging that idea, from the very first chapter.
In one category I see the stories of Star Trek and The CoDominium, / The Mote In Gods Eye. Both sets of stories revolve around a militaristic society where, even though there are democratic societies on frontier planets and back on Earth, the only travel between worlds is governed by the ruling group of technocrats who importantly are the only ones with access to interplanetary travel. These aren’t closely tethered warships like we have today: Star Trek plots are notable for the authority, autonomy and power that individual captains and their cadre of officers have. It isn’t explored in depth but Mote implies the CoDominium, the ruling structure on Earth and other worlds, is organized the same way the space faring military is run. Societies with a large military running the country day-to-day are usually considered technocracies (contemporary Egypt, for example.)
In Dune, the Navigators — a separate species evolved from humans — exert the same kind of authority over space travel. The fundamental access to other worlds is in the hands of their technocracy, though the other unevolved humans whose stories make up the main plot lines do so in traditional feudal empires. Maybe Navigators have their own ways of deciding how to run things that shows they are decidedly not technocrats, but to the extent that they control travel between worlds makes them technocrat overlords to everyone else.
Space travel and society in Banks’s Culture novels is much more democratic. Individuals roam in their own ships and all different kinds of societal structures are free to exist in many species and places. However, the over-arching control is still in the hands of the benevolent Minds — sentient supercomputers with a moral code that still allows for some humans to be involved in decision making, but only those humans that have been selected for their elite knowledge and skills. While the Minds have all the power, the humans call a lot of the shots. Decision making by only the most learned and skilled is the hallmark of a technocracy.
(As a teenager I loved this adventure and exploration focus; as an adult, I wish they had explored the Federation as a government and society a bit more.)
I haven't heard of CoDominium before, and The Mote In Gods Eye is on my todo list.
Come to think of it, I could sort of see the "technocrats leaving rest behind" in StarGate series, where most of the off-world activity, including bases on different planets, were actually run by the US military (later a cooperation of militaries and civilian agencies) in secret from the rest of the world.
Out of the relevant books I read, all featured either just human expansion (with no leaving behind happening), or alternatively remnants of humanity going out, with nothing salvageable left behind.
Re-reading your comment, I see you're focusing more on the "technocrats" aspect than "left behind everyone else". Honestly, having grown up watching Star Trek, I'm biased positively towards technocracy - but I guess it worked there because in the society the show portrayed, neither people nor organizations were dumb. Merit actually meant merit.
The problems you mention reach to the very core of human group dynamics. Colonizing space is orders of magnitude easier than solving them. If and when we do solve them, it would make us an extremely formidable civilization.
The people who went all in on what was the new thing at the time have states, cities, islands and whatnot named after thing
Infighting didn't exactly put a damper on the Europeans ability to colonize the Americas and exploit everyone else in the old world. Once we have the technical capacity to colonize other planets I doubt a little infighting on Earth is gonna stop us.
There's more hard evidence of "pseudo-magical objects that don't seem to wish to be seen up close" here on our Earthly radar systems than there is of the actual conditions on planets in neighboring habitable zones to confirm or deny life and start establishing probabilities.
It doesn't assume that. (Explicitly doesn't; that's step 9 of 9, with modern humanity at step 8.) It just observes that we have no evidence of extraterrestrial life spreading out from their home system and colonizing the universe, and discusses some possible reasons for that.
One of my favorite books on this is "Regenesis: How Synthetic Biology Will Reinvent Nature and Ourselves" by George Church. I have also seen arguments for this in "The Blind Watchmaker" by Dawkins that was published in 1986.