While it's difficult to imagine a scenario in which humanity extinguishes itself, it's easy to imagine scenarios which make civilized society difficult, and could preclude future advanced civilizations from ever emerging on Earth, these may constitute a variety of "hidden filters" which make exiting ones own solar system or mustering the energy to make oneself known impractical.
The article makes reference to a million year time horizon, however even earthly nuclear energy reserves may become strained on a thousand year time horizon. As we're all acutely aware, the great biochemical battery of fossil fuels is already operating on diminished capacity. Planet's such as mars lack the hydro-cycle to drive renewables, the organic legacy to support fossil fuels, and potentially the tectonics to enable surface extraction of nuclear fuels.
While a theoretical expansion outside of the confines of earths gravity to acquire resources from asteroids, or produce high concentrations of solar energy is currently achievable on a 20-100 year time horizon, supporting the energy demands of the aerospace supply chain or considering regular space launches may be difficult in 2 centuries. On a thousand year time horizon it's entirely plausible that maintaining a purely renewable economy makes the production of certain materials impractically expensive when considering the concentrated energy demands of blast furnaces or industrial mining.
Similar collapse events have occurred historically due in part to the exhaustion of limited resources such as forests have occurred in the past in both Europe and polynesia. If a similar event occurred in the future it's entirely plausible that a future civilization would be unable to muster the resources to ever "unlock" the next set of energy production capabilities.
Reaching a conclusion with so many unknowns (specially unknown unknowns) is risky.
That life must evolve in enough number of planets doesn't mean that the next one is close. And that interplanetary travel is practical doesn't mean that interstellar or intergalactic travel must be. And considering the speed of our current technological development, vs the time needed to get to the next stage in colonization, something big may emerge in the middle. Or something different and unexpected.
In some way, we are like churches deciding what and how a god may think. We are not at the right stage to judge based on our lack of knowledge or perspective. It may not be just one road forward, and going galactic may be the wrong one.
I prefer to take one step at a time, and solve our current roadblocks, if we can. Maybe we have the great filter in front of us in plain view and we can't recognize it.
I think the "great filter" is evolution itself. Life formed almost immediately that the conditions allowed for it.
But it took over three billion years of relative stable conditions for it go go past the stage of single celled organisms and even the cell itself took a long time to form. Higher forms of life are only 500 million years old and the human line only started taking shape the last few million years.
Personally I think the universe is teaming with life but intelligent/sentient life is exceedingly rare.
Dissolving the Fermi Paradox by Anders Sandberg, Eric Drexler, Toby Ord
> "This result dissolves the Fermi paradox, and in doing so removes any need to invoke speculative mechanisms by which civilizations would inevitably fail to have observable effects upon the universe"
The Fermi Paradox has essentially been resolved: https://arxiv.org/abs/1806.02404
This explanation is much more plausible than a Great Filter. Here's a great comment summarizing the argument very intuitively:
https://news.ycombinator.com/item?id=17562439
I also found this one very helpful:
Geoffrey West's work on the laws of life and metabolism might provide some insight. He shows that adaptations tend toward crashes so that survival requires constant ongoing adaptation to avoid self disruption. This means it is highly likely that advanced civilizations will tend to crash whether it is from their own consumption of resources or catastrophic changes that go beyond capacity for adaptation.
Life is a search algorithm for energy utilization. Arguably the only evolutionary benefit of intelligence is the ability to bridge troughs between local optima farther than genetics alone can. It has limits as much as genetics does. We like to think of intelligence as some boundless forever bootstrapping superpower but all growth curves end up being sigmoid. The hard question is are we close to topping out or are we just waiting on the next punctuation in the equilibrium. I think future punctuations will be found in "what comes after intelligence" in the search for increasingly efficient energy utilization?
I find the space colonization (outside own solar system) a bit too optimistic, while it is 'only' a technical problem, it still might be an impossible problem.
Recent data from New horisons mission is interesting, suggesting there are an order of magnitude fewer galaxies (hundreds of billions, rather than 2 trillion) which should be relevant update to Fermi/great filter reasoning.
The probe is near Pluto, and so able to sky 10 times darker than Hubble, but isn't observing the modelled galaxies extrapolated from Hubble observations.
https://www.foxnews.com/science/nasa-finds-fewer-galaxies-th...
If curious see also
I don’t think there is a singular great filter. Instead I suspect there is a relatively constant probability of a black swan event across the entire existence of a biosphere.
It took over four billion years to get from simple replicators to what exists here now. It is quite possible that most biospheres simply don’t make it that long without such an event.
We don’t know the probabilities, but over billions of years the continuous probability of biosphere extinction need not be very high to filter out almost all biospheres before they develop something capable of interstellar signaling or flight.
Keep in mind that another prior we don’t know is the probability of a diverse biosphere developing this type of intelligence. We have no idea if that is likely or not even given sufficient time and energy inputs.
Intergalactic flight is many orders of magnitude harder than interstellar flight, which in turn is many orders of magnitude harder than interplanetary flight. If the probability limits such intelligences to no more than an average of 1-2 per galaxy then there is your answer. We would be extremely unlikely to see intelligent aliens any time soon, even if we do find a lot of microbes.
Given where Earth is now I would be surprised if it does not hatch an interstellar scale intelligence at some point in the remainder of its habitable life. Will that be us? Hopefully so. Given that we are already almost there (on evolutionary time scales) it is reasonably likely it will be us or an AI we create.
Kurzgesagt has a ten minute video on the subject:
> among the billion trillion stars in our past universe, none has reached the level of technology and growth that we may soon reach.
May soon reach? I doubt it. I'd say there's a significant filter between our technology level and large-scale inter-solar-system colonization. It's not at all clear that there is a strong motivation for that - except for a continuous-growth economy, which is kind of unsustainable anyway. Once the population stabilizes and human civilization is basically energy-neutral (i.e. not taking more than the sun provides), where's the great need to colonize someplace else (as opposed to communicating)? And if we don't stabilize - civilization will burn itself out soon enough, colonization or no.
> Even if life only evolves once per galaxy, that still leaves the problem of explaining the rest of the filter
No it doesn't. It's extremely unlikely that one planet with life will travel to a different galaxy. Even with intelligent life it's extremely unlikely. Only if instantaneous travel were possible would this be likely.
Humans are doomed to die at the Heat Death of the universe. Science tells us our universe had a definite beginning, the Big Bang, and that this event will not repeat: there will be no Big Crunch, no reboot. SciFi authors prefer to ignore science so they can imagine immortal humans who survive the cycle of infinitely rebooting universes. If we colonize the stars and galaxies we can postpone our death a few trillion trillion years, but eventually the last star will snuff out, the last black hole will evaporate, and there will be no energy left to power the phenomena of intelligence and consciousness, and life shall be no more. The last humans will have to bravely face certain and inevitable death just as our prehistoric ancestors did, and just as you and I must.
Every time this sort of thing comes up (the Fermi Paradox, the Great Silence) I like to point out that it says more about the person than the real world. To wit: there is no time or culture in the history of the world where humans have not been in contact with some kind of "otherworldly" intelligence.
Personally, (not that anyone asked) I think we're in quarantine. I think that most intelligent species rapidly reach a peaceful "win-win" equilibrium, that we humans are rare or even unique in our violence, that this is because of some specific but forgotten event (maybe the Younger Dryas, I don't know) that traumatized us and triggered the development of agriculture and cities, that those are degenerate forms of civilization that perpetrate the trauma that leads to our current malfunctions, and that we are essentially in a hospice-type situation vis-à-vis the little green men.
So, um, there? Have a nice day y'all.
I think it's much simpler than that: if there is intelligent life, it is at the same level of development that we are.
I don't think we're far enough along in tinkering with subatomic physics or gravity to know whether we've passed the great filter or not.
Hell, we haven't even managed to guarantee human rights to every person on the planet yet. We've got a ways to go.
"Life Will Colonize" "So far, life on earth seems to have adapted its technology to fill every ecological niche it could."
Not any more. As technology has advanced, and agriculture has become less labor intensive, there's been a sizable cutback in populated area in the US and Japan, at least. Farms in less productive areas are not competitive and those areas are emptying out.[1] Towns which serviced the farms are dying off with them.[2]
[1] https://www.visualcapitalist.com/u-s-population-change-by-co...
[2] https://en.wikipedia.org/wiki/List_of_ghost_towns_in_the_Uni...
I think technology acts as an amplifier to our impulses, both good and bad. The more technology, the more sensitive the balancing act, to stop civilisation going off the rails. We are not sufficiently balanced. The sort of tech required to conquer the stars, in human hands would probably lead us to wipe ourselves out within an hour of getting hold of it.
When you realize that even if by some miracle we find a way to travel at really fast speeds we will never explore 99.99999% of the universe is mind boggling.
This video by Kurzgesagt explains it well: https://www.youtube.com/watch?v=ZL4yYHdDSWs
I don't see much of a future for sending people off earth. It's very complex and expensive to drag a bubble of earth along.
We should just send robots and move all the messy stuff off the planet so we can try to restore the planet to being a human-oriented paradise.
Maybe by the time a civilization achieves the tech needed to really expand, they no longer want to.
What if there is unlimited number of The Great Filters. What if we are already Nth contingency plan seeded on Earth by N-1th parent life form(s) woring about the same problem - to survive, replicate further onto closest places as N+1 backup.
I love the theory of Great Filters. I'm pretty sure that #9 on the list should be "social media", though. Or in general, "self destructing human behavior."
Climate Change will be the great filter for humanity.
The thing I keep seeing people miss is the narrow slice of time that we have existed in a technological state to be broadcasting and/or looking. Assuming exponential distribution, this is most likely to only last further as long as it has already. And with us as the only example, it would most likely be the same for others. So 50 years out of 5 billion on the planet and 3 billion since life began. Are there 100M stars within radio range? Do we even have time to point antennas at each one long enough to get a signal? That’s about 15 seconds each. How many bands do we need to scan in that time?
Any hope of contact or expansion requires an extremely long period of sustainable existence in a state of constant technological development. Most of modern humanism is antithetical to this. The entire world today seems focused on expanding consumption. This is especially true of both colonialism and immigration. Economist today judge an economy by its internal consumption rather than older notions like export productivity. Seems like we’re going to have to reconsider policies and priorities if we want to make it out of here.
(1998)
Carbon is great filter
It's low orbit pollution with high speed space junk by any technological civilization,resulting in an inevitable self-interdiction of space flight: https://www.economist.com/science-and-technology/2000/03/23/...
I've wondered if the first of the great filters isn't simply water.
Assuming something like octopuses evolved into a relatively long lived tool-using species with complex communication, they would be infinitely hampered by their environment. Even if they were lucky, as we were, and their planet had available great reserves of fossil fuels, they could not burn them. They cannot invent fire. Without fire, they have no way to invent metallurgy. Or glassworks. Or plastics.
What are the odds of having enough water for life to spark without having so much of it that it blankets the surface? Anything evolving on worlds with little land seem unlikely to ever escape their world.
Life could be commonplace, but if most worlds it evolves on are 99% water, we would never see it or hear it. The universe would be silent.
It may be our luck in simply being terrestrial rather than aquatic that separates us from our apparently absent galactic cohabitants.
Being in a position to be capable of taking advantage of burnable trees, and later coals and oils may be beyond rare in the universe.