patrick.net

I just had a chuckle because someone disliked this thread. It just goes to show how meaningless likes and dislikes have become. They are just political tools now based on whether or not a user likes the author, not at all based on the content of a thread or post. Still, it's nice pissing off the trolls so much that they obsessively dislike everything you post. It says I'm effective.

The alternative is that the spacefaring species of the galaxy have already organized and are awaiting a technological queue to invite/demand us to be part of their empire. Stop thinking so small!

Ironman says

No, it just shows how useless your posts and threads have become!

Feel free to explain why you think the Fermi Paradox is useless. It will be a great example of how small-minded you are.

Ironman says

Reading comprehension issues again?? I said YOU were useless!!

Ironman says

No, it just shows how useless your posts and threads have become!

You have such poor reading comprehension, you don't even comprehend your own posts. Selective memory is a sign of delusion.

So again, feel free to explain why you think the Fermi Paradox is useless. It will be a great example of how small-minded you are.

Isacc Arthur has some great videos on his channel including a series on the Fermi Paradox.

Here's a particularly good, and long, description of proposed solutions to the paradox.

www.Z4snQS1QGD4

My take is that there are three likely answers.
1. The conditions needed to achieve complex life are much less common than we assume. (1A in the above video)
2. Intelligence to the extent needed to master mathematics and science is not a common outcome of evolution. (First part of 1B)
3. Intelligence does not often lead to technologically advanced civilizations. (Second part of 1B)

These are the great filters I think exist and how difficult I think they are to overcome on a scale from 0 to 10. When I use the term earths in this scale, I mean a planet in which life has already generated a stable ecosystem.

The Life Difficulty Scale (LDS)
0 - No obstacle
1 - Most life will get pass it quickly within tens of millions from encountering the filter
2 - It is rare that an earths won't produce life that breaks through in under a billion years
3 - It is rare that an earths won't produce life that breaks through within a few billion years
4 - Almost all earths will eventually produce many lifeforms that break through
5 - Life on most earths will get pass it eventually
6 - Some earths will produce life that gets past it
7 - Few earths will produce life that gets past it
8 - Few earths in a galaxy will produce life that gets past it over the entire lifetime of the galaxy
9 - Few galaxies will ever produce life that gets past it before the heat death of the universe
10 - impossible to get past

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The conditions needed to achieve complex life are much less common than we assume.

1. Complex life needs a large moon around an Earth-like planet to stabilize the climate so complex life or intelligent civilizations can emerge. This involves either perfectly capturing a sister planet or colliding with a sister planet at just the right angle to form a moon like what happened to Earth Mark I. I'm not convinced that this is necessary, but if it is then complex life would be rare.

Difficulty: 7

2. Complex life requires a symbiosis like mitochondria or chloroplasts to happen. Life on Earth didn't have the metabolism necessary to extract enough energy to become complex before one of our ancestors ate a mitochondria and it lived and formed a symbiosis with its host.

Mitochondria formed this symbiosis with our ancestors about 1.5 billion years ago. That's a very rough estimate based on the fact that the oldest fossils of Eukaryotic cells are dated to that period. The actual date may be earlier or later. But let's use that rough estimate until we have a better one.

That means that life, which began about 4 billion years ago on Earth, took 2.5 billion years to form this relationship. A similar thing happened with cyanobacteria surviving an eating and becoming chloroplasts in plants. There are only two instances we know about when a single cell organism got eaten by another and survived to form a permanent symbiosis with the creature that ate it. This seems to be a very rare event, and Earth had two!

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Maybe Earth also got lucky that these two extremely rare events happened relatively quickly. If it took Earth 2.5 billion years to roll the dice correctly, it is not unreasonable to accept the mean time for such an event to be ten times as long or 25 billion years, over twice the age of the universe. Of course, using a normal distribution, some planets will roll sixes in less time than 10 billion years, the rough time for solar systems seeded with heavy elements created by earlier stars to form life, but it could be just a few per galaxy or even on average less than one per galaxy.

Now I'm not sure that such a symbiotic relationship is needed, but it seems very strange that all complex life on our planet has at least the mitochondria symbiosis. Maybe the mere existence of this relationship caused the organisms with it to outcompete all other possible evolutionary paths of producing high metabolisms, but since prokaryotic cells are still abundant and haven't once evolved a competing mechanism that we know of, it seems like there probably isn't any workable competing mechanism or they are much harder to evolve and would take even longer.

Difficulty: Between 7 and 9.999. Best guess: 8. This is the greatest filter in my estimate.

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Intelligence to the extent needed to master mathematics and science is not a common outcome of evolution

3. Clearly intelligence has emerged independently in multiple lineages, and animal intelligence is greater than humans have given credit to it. However, only one species on this planet does abstract mathematics, and it happens to be the species that uses extensive agriculture and also has language. Some other species may have language, like dolphin and whale species, while others have the capacity to learn sign language, but those do not have the vocal cords for language.

Language and mathematical thinking are very rare, if not singular to our species on this planet. Both would be needed to set a species on the course of civilization.

Difficulty: 6

Intelligence does not often lead to technologically advanced civilizations.

4. Dolphins are intelligent, perhaps about as intelligent as humans. However, they will never build a space-faring civilization because they live in the ocean and you can't smelt metal underwater. Also, species without opposable thumbs won't be good tool makers. And species that don't have free arms can't impact their environment because they can't carry materials far. So you need at least six limbs or both at least four limbs and a bipedal stance.

Difficulty: 6.5

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Or that speeds approaching anything like speed of light for spacecraft are simply impossible because physics.

For underwater creatures, add in the need to carry heavy ass water environments. Imagine if Gagarin had to sit in a few extra tons of filtered sea water to survive his trip into space...

Summary

In summary, each of the above filters makes it take way longer for a space-faring civilization to emerge in a galaxy. The need for a symbiosis for energy production may make such civilizations very rare, and in fact, complex life very rare while primitive life, even multicellular primitive life, is common.

Therefore, I think that the reason we haven't encountered space-faring aliens, or why they didn't colonize the Earth before the dinosaurs were wiped out, is that we're simply the first space-faring civilization in our galaxy. There could be another, but given the short period of time until such a civilization colonizes the entire galaxy in contrast to the time during which it can emerge, it's highly improbable that one is developing just as we are.

T L Lipsovich says

For underwater creatures, add in the need to carry heavy ass water environments. Imagine if Gagarin had to sit in a few extra tons of filtered sea water to survive his trip into space...

So no Lovecraft style sea-monster aliens then.

Life may not be uncommon, and intelligent life that's tool making or curious isn't that uncommon, but it's far between and since there is no method to transfer between star systems and explore in reasonable time frames... I mean it's multiple years to the next star system at the speed of light, at a fraction of it it's a multigenerational trip at least...

So you could have many intelligent species, they are just separated by 100s of LYs, but can't even visit their Alpha Centuri in a reasonable timeframe because anything past 1% of Light Speed isn't viable.

We hope wormholes exist, or Alcubier (sp) drives exist, but they very well could not, or would require so much energy to utilize...

Even at 1% of the speed of light, it would take a single space-faring civilization a mere 20 million years to colonize the entire galaxy even starting at one edge of it and preceding across the entire thing. Let's say such a civilization started anytime between 10 billion years ago and 4.6 billion years ago. They would have colonized the entire galaxy before our sun was created. They would have mined or colonized Earth early in its history before multicellular life evolved.

Let's say such a civilization emerged when the dinosaurs rose 230 million years ago. They would have colonize Earth before the T-Rex evolved. If they started when the dinosaurs were wiped out 65 million years ago, they would have colonized the Earth shortly after the first monkeys evolved, and long before apes.

For them to be both space-faring and not yet having reached us, they would have had to start their first colony a mere 20 million years ago. That's a window of 20 million years within a 10 billion year larger timeframe (and 10 billion is conservative). The chances of that happening are 20 million to 10 billion or 0.2%. And that's a high estimate that assumes another space-faring civilization has existed in this galaxy. Remove that assumption and the probability falls exponentially.

The probability also falls if it is practical to travel at more than 1% of the speed of light. If they can do a mere 10%, it only takes 2 million years to colonize every habitable planet.

Remember, population growth will be exponential and migration constant from more densely populated areas to lesser densely populated ones. This means that the only bottleneck is travel time, not colony setup and growth time.

Dan8267 says

Even at 1% of the speed of light, it would take a single space-faring civilization a mere 20 million years to colonize the entire galaxy even starting at one edge of it and preceding across the entire thing. Let's say such a civilization started anytime between 10 billion years ago and 4.6 billion years ago. They would have colonized the entire galaxy before our sun was created. They would have mined or colonized Earth early in its history before multicellular life evolved.

Well, let's say the nearest star was 7 LY away. How long would it take a ship to get there? And how massive would it have to be, and how would it get resources with no "in situ" to glean them from? Would successive Generations have the discipline not to turn the ship around? Maybe they'd form cliques and kill each other or seriously damage the ship over the Whites Vs. Blues 0-G Football Game. I could see 3-4 Generations surviving no problem because parents/grandparents would be all about the mission and there'd be enough "old Earthers" to keep the kids in line. After that, living on a ship is all the next generations will know, while knowing THEY will never see a planet of any kind. Why bother learning? They ain't gonna see shit or do shit but hang out on the ship. Let the final generation learn science from the computer. Bored people act up. Will they stay the course?

What would number of species with the vision/willingness/discipline to even get to the nearest star system?

Our asses haven't left Low Earth Orbit since before I was born, and I'm about 40. Even though we could pretty easily send people one way to Mars with Tech from the 70s. I don't think returning should even be considered except as a tertiary objective.

I don't want to be a downer, but the only way we're gonna get our ass to Mars is if we have an extremely powerful person who rams it through and funds it "Big League" so it happens in less than 8 years, OR if China, Russia, or India make serious attempts to do so.

The latter case is far more likely.

Dan8267 says

Lovecraft

Paging Cthulu.

T L Lipsovich says

Well, let's say the nearest star was 7 LY away. How long would it take a ship to get there?

I don't believe that would act as a great filter due to the non-exclusivity principle. All it would take is one species to have even a few members that are willing to endure the long trip either awake or in cryostasis.

The trek between stars in a galaxy isn't that far. The trek between galaxies would have to take many, many generations, and the payoff wouldn't come before the investors, their children, and their grandchildren were long dead. I can see intergalactic travel as being a great filter, but not interstellar travel. As such, there may be zero or one star-faring species in every galaxy with darn few exceptions where two species emerged at the same time, a rare event.

The only resolution I can see to make multiple civilizations running at the same time is the popular in SciFi but no reason to believe it plotline "precursors fucked things up". It goes like this. A precursor species is the first to reach space and colonizes the entire galaxy hundreds of millions of years before anyone else evolves. Then either this precursor species directly fucks things up or creates something that fucks things up. Either way, the fuckers wipe out all sentient life or space-faring civilizations in the galaxy, including the precursors if they aren't the fuckers, but leave the rest of life alone.

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Primitive life continues to evolve. Primitive cultures as well. The next time one becomes space-faring, the fuckers return and do it again. This cycle repeats, and since evolution and technological development for primitives is allowed to continue unabated, more and more planets get to the point of supporting advanced civilizations. The cycles get shorter, and more species reach space each subsequent cycle. This allows for multiple civilizations simultaneously in later cycles.

Popular in scifi, but no reason to believe it.