Is the Milky Way harboring dozens of intelligent civilizations?

[Admin]

Are dozens of intelligent extraterrestrial civilizations lurking right in our home galaxy?

Is the Milky Way harboring dozens of intelligent civilizations? : Read more

 

[rod]

This is an interesting report. "The second limiting criterion focused on stars. They estimate that a planet with intelligent life would orbit a star like our sun (because life has formed here on Earth, which orbits the sun). This sun-like star would have "a metal content equal to that of the sun … (the sun is relatively speaking quite metal-rich)," Tom Westby, an assistant professor at the University of Nottingham and first author on the paper said in the same statement...Taking these criteria into account and under these numerous assumptions, the researchers made an approximate estimation of the number of intelligent civilizations that could theoretically exist in the Milky Way. "We calculate that there should be around 36 active civilizations in our galaxy," Westby said. However, the average distance to these alien worlds would be approximately 17,000 light-years, so much too far for humans to contact with existing technologies, according to the researchers."

Apparently class G type stars were used in this study vs. class M, red dwarf stars. This exoplanet site shows 763 confirmed exoplanets found around stars with masses 0.95 to 1.05 solar masses in my MS SQL Query (most are class G stars), http://exoplanet.eu/ Another site I use shows 645 exoplanets for 0.95 to 1.05 solar mass stars, https://exoplanetarchive.ipac.caltech.edu/index.html

This new study indicating perhaps 36 *active civilizations in our galaxy*, places serious constraints on those who claim UFO sightings must be visitors from other star systems.

 

[I_believe]

I heard that report yesterday and was just about to ask about it.. Apparently it takes 5billion years for intelligent life to form? How do they come to that metric?

 

[Cosmo47]

I heard that report yesterday and was just about to ask about it.. Apparently it takes 5billion years for intelligent life to form? How do they come to that metric?

They came to the "5 billion years to evolve intelligent life" number by looking at how long it took humans to become 'intelligent' after the formation of the Earth. Answer: 4.5 billion years (as microbial life appeared soon after Earth became Earth). I found this number to be sort of 'squishy' in that Earth is a sample size of 1. I'd much rather have 2 or 3.

 

[Jason K]

Apparently class G type stars were used in this study vs. class M, red dwarf stars. This exoplanet site shows 763 confirmed exoplanets found around stars with masses 0.95 to 1.05 solar masses in my MS SQL Query (most are class G stars), http://exoplanet.eu/ Another site I use shows 645 exoplanets for 0.95 to 1.05 solar mass stars, https://exoplanetarchive.ipac.caltech.edu/index.html

This new study indicating perhaps 36 *active civilizations in our galaxy*, places serious constraints on those who claim UFO sightings must be visitors from other star systems.

Rod, I don't have access to the full article, but from the abstract, it appears the authors acknowledge that most of these potential civilizations would be found around class M red dwarf stars: "Furthermore, the likelihood that the host stars for this life are solar-type stars is extremely small and most would have to be M dwarfs, which may not be stable enough to host life over long timescales."

While I love the authors' optimism for intelligence in the universe, the article surely can only be another attempt to quantify the Drake equation. And the problem here is that there are massive unknowns in the terms of the Drake equation, mostly in what events in Earth's history represent major or minor filters on the biological progression that eventually allowed for the emergence of sentience. For instance, we know our large moon was certainly a factor in that it stabilizes our axial tilt over cosmological spans of time.... but is this a major filter that is crucial for long-term biological stability and diversification that only a very small percentage of potential habitable planets are likely possess, or a more minor filter? We don't know, because our current exemplar sample size is one. Another potential major filter is the presence of a large gas giant to keep debris strikes to habitable-zone planets relatively low enough to not completely disrupt biological evolution every few million years. Is Jupiter a major filter for the development of intelligence on Earth, or is it a more minor factor? Again, exemplar sample of one, so we don't know.

In the end, each attempt to quantify the Drake equation ends up showing the researchers' particular biases in regards to what they see as a significant versus a minor hurdles in the evolutionary chain. And to make matters worse, we cannot quantify those biases, because our only sample for intelligent life is one. In effect, we know that there is much that we don't know, but we don't know how lacking our knowledge might be, or how accurate or erroneous our assumptions really are. In short, the numerical solution to the Drake equation can be as low as one (us), or as high as several thousand, depending on the assumptions made about what constitutes major versus minor filters in the terms of the equation.

Still, it's always a fascinating thought experiment. And as I said, I applaud the authors' optimism in their assumptions which led to their answer of 36 civilizations. I personally am not as optimistic, but do believe the number to be greater than one ... although I'd be extraordinarily surprised if there were ever more than one active at the same time in our galaxy.

-Jason

 

[rod]

FYI, the quote you provide Jason appears to focus on M class or red dwarfs but the space.com report and others I read make it clear that the focus was G class stars similar to our Sun, "The second limiting criterion focused on stars. They estimate that a planet with intelligent life would orbit a star like our sun (because life has formed here on Earth, which orbits the sun). This sun-like star would have "a metal content equal to that of the sun … (the sun is relatively speaking quite metal-rich)," this from the space.com report. Another report shows the same criteria, https://phys.org/news/2020-06-intelligent-life-galaxy.html. However you are correct about the abstract, https://iopscience.iop.org/article/10.3847/1538-4357/ab8225, "Furthermore, the likelihood that the host stars for this life are solar-type stars is extremely small and most would have to be M dwarfs, which may not be stable enough to host life over long timescales. We furthermore explore other scenarios and explain the likely number of CETI there are within the Galaxy based on variations of our assumptions."

If the model tosses out class G type stars like our Sun and focuses on M, red dwarf stars, it seems the constraints placed on UFO reports claiming they come from the stars is even more restricted and difficult with so many red dwarf stars and only 36 likely civilizations arising, mostly on red dwarf stars with exoplanets. This assumes that abiogenesis works similar to model(s) for abiogenesis on Earth and natural selection will work similar too, creating an evolutionary tree of life that results in intelligent life emerging and flourishing to create a civilization.

 

[rod]

FYI, I find M dwarf star hosts very intriguing when it comes to extrapolating the emergence of intelligent life on an exoplanet orbiting such stars (and the assumption that abiogenesis and natural selection will work similar to our Earth). Here is a recent example with a 3.14 day period, http://exoplanet.eu/catalog/epic_249631677_b/ The planet is about 0.0234 AU from the red dwarf star.

 

[FrankT]

Recently, there were a few video footage declassified by the Pentagon, showing UFO flying with our fighter jets in mid air. One of them was narrated as suddenly dropping from 28,000 ft to sea level in 0.7 seconds. A few clicks on the calculator said that roughly equals to falling at 27,000 mph, with instantaneous acceleration and deceleration, as if inertia did not exist. Whoever or whatever inside that vehicle or controlling it, has to be pretty intelligent.

 

[rod]

So applying the 36 civilizations model for the red dwarf stars in our galaxy using the science in the new report, which red dwarf star did the UFOs come from flying around the fighter jets? We have 261 confirmed exoplanets reported around stars with masses 0.08 to 0.5 solar masses, and this includes the TRAPPIS-1 system, http://exoplanet.eu/

 

[George B.]

This research did not use the Drake equation, which I've always thought was too optimistic to begin with because the 7th term L ( the length of time for which such civilizations release detectable signals into space) should be the fraction of time a civilization is releasing detectable signals into space over possible time the civilization could exist (this would reduce the number of possible civilizations by the Drake equation by several orders of magnitude...a possible answer to the Fermi Paradox).

This new research does acknowledge the question about how long such a civilization could exist (better yet...how long it would use electromagnetic emissions (i.e. radio) to communicate information, which would be shorter than its time of existence). In short, what is the probability of these 36 civilizations existing (i.e. overlapping) simultaneously?

"Despite the new estimate, the researchers acknowledge it's still very possible that we could be alone: If other broadcasting civilizations exist, they might not survive for as long as humankind has and so we might not exist at the same time. "

 

[rod]

This research did not use the Drake equation, which I've always thought was too optimistic to begin with because the 7th term L ( the length of time for which such civilizations release detectable signals into space) should be the fraction of time a civilization is releasing detectable signals into space over possible time the civilization could exist (this would reduce the number of possible civilizations by the Drake equation by several orders of magnitude...a possible answer to the Fermi Paradox). This new research still does not account for how long such a civilization could exist, or even how long it would use electromagnetic radiation (i.e. radio) to communicate information, which would be shorter than its time of existence. In short, what is the probability of these 36 civilizations existing (i.e. overlapping) simultaneously? The report does account for this possibility:
"Despite the new estimate, the researchers acknowledge it's still very possible that we could be alone: If other broadcasting civilizations exist, they might not survive for as long as humankind has and so we might not exist at the same time. "

And this quote provided from the report shows more constraints for those claiming the UFOs are space ships visiting from the stars.

 

[FrankT]

The elements necessary for life is not sufficient for intelligent life forms. It took billions of years for the first divided cell to become dinosaurs on the Earth. Dinosaurs had lived for some two hundred million years before they were wiped out. In their two hundred million years of survival, fire was not mastered, compass was not invented, electricity was not tamed, not to say harnessing the energy from an atom. Yet, the human species who had only started to walk a few million years ago, has accomplished all that in the last one million year. Do we know why?

 

[rod]

Here is a quote from a source I use that suggest a why answer perhaps, "[2. Evolution is dynamic and creates huge changes over time, except when it keeps everything the same for millions of years. The General Theory of Evolution5 suggests that non-living chemicals spontaneously arranged themselves into single-celled organisms.6 Over time—and through many other life forms—this ongoing evolution culminated in mankind.7 Yet, this story is in stark contrast to the evidence of so-called ‘living fossils’.8 These are creatures alive today which, when compared to fossilized remains of the same, look remarkably similar, showing little to no signs of change.]

 

[davea0511]

I heard that report yesterday and was just about to ask about it.. Apparently it takes 5billion years for intelligent life to form? How do they come to that metric?

This sun is a 3rd generation sun. We know this because of the quantity of heavy metals. The universe is about 13.8 billion years old, so divide by 3 ... About 4.5 billion each, round up to 5. Actually the first two generations probably formed faster, as with each supernova the elements get spread out further. The first one formed pretty fast due to clumpy matter. Anywho that combined with the paleontological record ... It's all pretty much done with huge assumptions so it's more like +/- 1 or 2 billion years.

The thing is, and they don't really mention this, it appears when you do the math that we're among the first intelligent species in the galaxy. The rate of evolution seems like it has been full power since the BB, no rest for the wicked. That's why they calculate only 30 possible alien civs. That's incredibly small considering that there are roughly 259B stars in our galaxy. In another 100M years maybe there will be 10k civs out there. Then again maybe the window for potential life is incredibly small, and has to evolve at max rate if it is to ever exist at all.

Regardless, this evaluation I believe is spot on despite all the assumptions, and is, I admit, discouraging if anyone was hoping for a Valerian type universe.

But it does suggest one thing in which I find solace ... That something ... Call it the universe if you must ... Something seems to have some kind of objective to get us here at this time as soon as possible. But maybe that's just an aberation.

 

[Jason K]

This research did not use the Drake equation ....

Nevertheless, they still have done some form of multiplicative probability assessment in a similar fashion to the Drake equation, even if they utilized different terms than Drake; probability of X times probability of Y times probability of Z, etc., equals 36. As I said, I cannot access the article directly, only the abstract, so I don't know what exact terms they used for their formulation, or how they quantify their error bars.

I'm assuming that the focus of the research was less on finding a definitive number of possible CETI civilizations and more on establishing theoretical upper limits on how many such civilization we might expect to exist at one time? Those are related goals, of course, but the tone of the final analysis is different. The former is saying "there are X" plus or minus some number, while the latter is saying "there may be X, or there may only be only one, but there certainly aren't 1000X". I may have to break down and buy the article when it's available to do so...

 

[Jason K]

Regardless, this evaluation I believe is spot on despite all the assumptions, and is, I admit, discouraging if anyone was hoping for a Valerian type universe.

Now I'm curious. From davea0511's quote here, is the general consensus of the community here that 36 civilizations seems like a low number? Curiously, when I read the space.com article, I took it to be still a rather large figure. I guess I'm more of a pessimist in regards to extraterrestrial evolution than I realized. But I am a proponent of more major filters as a response to the Fermi paradox, so on the whole I suppose that's not too surprising.

 

[rod]

"...is the general consensus of the community here that 36 civilizations seems like a low number?" My thinking, 36 is a number that is conservative recognizing the assumptions and variables involved like how many exoplanets orbiting close to their class M stars in a habitable zone, retain their atmospheres as the system evolves, especially when the red dwarf stars are young. https://phys.org/news/2020-06-newborn-exoplanets-cooked-sun.html

Reports of Proxima Centauri b place this 1.17 earth mass exoplanet in the red dwarf habitable zone (period 11.2 days) but other reports indicate the surface temperature could be -57C. http://exoplanet.eu/catalog/proxima_centauri_b/ shows the surface temperature is 216K, -57C. Very cold Other reports indicate, "Having said that, although Proxima b is an ideal candidate for biomarker research, there is still a long way to go before we can suggest that life has been able to develop on its surface. In fact, the Proxima star is an active red dwarf that bombards its planet with X rays, receiving about 400 times more than the Earth.", https://phys.org/news/2020-05-espresso-presence-earth-nearest-star.html

 

[Wolfern]

Expecting intelligent life elsewhere is rich. Please let me know when it is found here, on earth.

 

[egribble]

Are dozens of intelligent extraterrestrial civilizations lurking right in our home galaxy?

Is the Milky Way harboring dozens of intelligent civilizations? : Read more

My thoughts are that we simply do not know. It is fun to speculate and we must continue to look (seti etc) but we simply cannot even guess as to the likelihood of their being life elsewhere. The problem is that we only have one part of the equation. We know there are 200-400 billion stars in the Milky way. We know the Milky way is only one of maybe 200 billion galaxies in the observable Universe. We know that there are more stars in the observable Universe than grains of sand on this planet. We know (thanks to Kepler space telescopes) that most stars have accompanying planets in orbit. However there is a big part of the equation we do not know. That is the probability of Abiogenisis happening. We have examined single celled organisms on this planet. All life including the most primitive extremeophyles has the same DNA structure with the same 23 Amino Acids. This suggests there was no co -evolution on earth, Abiogenisis only happened once on this planet (or possibly Mars if Panspermia occurred between the two planets). So this reduces the likelihood of it happening elsewhere. What if the likelihood of getting from self replicating molecules to single celled organisms on a Planetary surface is a trillion times less than the total of all the trillions of planets out there? This would mean we are totally alone in the Universe, only we can give meaning to the Universe because only we can contemplate it. We simply do not know.

 

[Tihamer]

Any scientific hypothesis about intelligent alien life that does not provide a possible solution to the Fermi Paradox is not worth reading. One that does not even mention it is not worth publishing.

However, FrankT asks a great question!

The elements necessary for life is not sufficient for intelligent life forms. It took billions of years for the first divided cell to become dinosaurs on the Earth. Dinosaurs had lived for some two hundred million years before they were wiped out. In their two hundred million years of survival, fire was not mastered, compass was not invented, electricity was not tamed, not to say harnessing the energy from an atom. Yet, the human species who had only started to walk a few million years ago, has accomplished all that in the last one million year. Do we know why?

Having a big brain does have it's advantages, but if you can't build tools, it can be a significant energy drain. Given human development, I'd say that there are a number of serious filters that we had to pass before getting to the stone ax. First (about five million years ago), we had to start going back to the water. I am not sure why, but we are the only primate that has vestigial webbed fingers and toes, not to mention being almost hairless (among other traits). The question of how returning to the water increased intelligence for apes; the intelligence of whales and dolphins (but not seals) indicates that there my be some subtle reason. However, then we invented fire (about 2 million years ago), that interrupted that seaward path--possibly at the exact right stage. Soon afterwards (again, about 2 million years ago), we started persistence hunting, which increased our intelligence because our smart ancestors did not loose track of the same individual prey they were chasing (the dumb ones died out before they could become our ancestors; evolution in action). More importantly, our ancestors's cardiovascular system improved to the point that it increased lifespan significantly; while all that running made female hips smaller, meaning that we had to be born prematurely. These drivers required more sacrifice from the parents, but also increased the importance of nurture over nature--making possible culture, including the significant advance in culture: technology.

At any rate, my guess is that we have passed many difficult filters. But we don't need to worry about them any more. The fact that there aren't Cerenkov radiation wakes crisscrossing the galaxy between Dyson rings brings me to the conclusion that there are some significant filters ahead of us. Filters that should scare the living daylights out of us all.

 

[7I7C1F3R]

They came to the "5 billion years to evolve intelligent life" number by looking at how long it took humans to become 'intelligent' after the formation of the Earth. Answer: 4.5 billion years (as microbial life appeared soon after Earth became Earth). I found this number to be sort of 'squishy' in that Earth is a sample size of 1. I'd much rather have 2 or 3.

Tossing out numbers as if we had any certainty to our own intelligent evolution is pretty human. Just sayin.

 

[Jabbadonut]

Are dozens of intelligent extraterrestrial civilizations lurking right in our home galaxy?

Is the Milky Way harboring dozens of intelligent civilizations? : Read more

The universe is extraordinarily vast. Its size really is beyond our ability to truly comprehend. That being said, the incredible diversity of types of life on this planet implies that life itself can take many forms. Additionally, the fact that humans exist as self-aware life forms proves the universe is capable of producing such life. I suspect that intelligent life exists wherever it physically can exist. I also suspect that that some of that intelligent life is likely to be as different from us as we are from the other types of life here on Earth. There was an interesting series on Netflix regarding contact with extraterrestrials that were passing through our solar system. They were so different from us that communicating with them was virtually impossible. Imagine a race of intelligent beings a million years more advanced than we are. How could we possibly hope to understand them? I've always believed that when some space faring race of intelligent beings wants to contact us, they will. Until such time we have no chance of actually contacting intelligent aliens. THEY are in charge of that, not us. When they want to let us know they exist, they will. Until such time we are just going to fail at every attempt we make to find intelligent life.
Ultimately I believe is that our universe is teeming with life, and that such life exists in various states of evolution. Some older than us, some younger than us. Once we have learned how to travel to other stars, the question of is there other life in the universe will be answered. Until that day comes, however, I expect all attempts to find life will be unsuccessful. This is all just my opinion, and I could be wrong.

 

[ImmortalMelvz]

In other galaxies, yes, there are intelligent civilizations far more advanced that is keeping in touch with us. In the Milky Way, yes also and they are now living with us teaching us to take care of our own beautiful planet.

 

[Tihamer]

The universe is extraordinarily vast.

Yes. As Douglas Adams put it, "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."

Its size really is beyond our ability to truly comprehend.

I don't think you appreciate how much humans can comprehend.

True, we can't comprehend infinity, but given the time since the big bang, we *can* comprehend the size of the universe fairly easily: if the big bang occurred 4.3 billion years ago, and the expansion occurred at the speed of light (at most), then the universe is less than 4.3 billion light years across. Possibly twice that measured from the center, but there is so center,. That is where our comprehension starts going off the rail, but it's fine until then.

That being said, the incredible diversity of types of life on this planet implies that life itself can take many forms. Additionally, the fact that humans exist as self-aware life forms proves the universe is capable of producing such life. I suspect that intelligent life exists wherever it physically can exist.

Yes and no.
What you are missing is how the the intelligent life gets there.

For example, Homo Sapiens lived in Africa for almost 300,000 years before we showed up in Americas 20,000 years ago. Not because we couldn't.

If you are implying that intelligent life will appear every where that it can survive (presumably through abiogenisis or panspermia and then evolution), then you are making some really big assumptions. Having a very big brain is metabolically quite expensive, and there are lots of difficult filter we had to survive in order to get to where we are now (and there are probably a number of huge ones ahead of us too!).

For example, what is necessary for tide pools and deep sea vents--places biologists usually mention as being necessary for providing the metabolic energy and the evolutionary pump for multicellularism? You need a very large moon not only to thin the crust (without the Moon we would be like Venus) for tectonic plates to happen (and deep sea vents to appear). Also, you also need that same large moon to cause tides (hence tide pools). Otherwise the environment is too static for anything to happen. The thing is, double planets like Earth and Luna are very rare.

There are at least a dozen other filters (some of which we don't know about), without which we would still be as dumb as fish. You can't have a water world because it's kindof difficult to start fires. More to the point, why are killer whales so much smarter than sharks? Does intelligence depend on having dry land? You need to do persistence hunting to develop intelligence, not only so that hunters must become intelligent enough to always chase the same individual prey, but also so that the running females small hips force the young to be born prematurely--enabling environment (such as culture and technology) to play a larger role compared to instincts.

I also suspect that that some of that intelligent life is likely to be as different from us as we are from the other types of life here on Earth.

That would seem a reasonable assumption, though what you mean by "different" is unclear.

There are many instances of parallel evolution here on Earth; it would also be reasonable to for intelligent life to be quite similar to us.
Artificial Intelligence pioneer Marvin Minsky proposed that we would have a relatively easy time communicating with intelligent aliens because mathematics and physics is the same across the universe, and provides the common ground for understanding. Theologians like Thomas Aquinas who share a similar belief in objective truth would probably agree (though in this case the objective subject matter is different).

There was an interesting series on Netflix regarding contact with extraterrestrials that were passing through our solar system. They were so different from us that communicating with them was virtually impossible. Imagine a race of intelligent beings a million years more advanced than we are. How could we possibly hope to understand them?

If it's "made of TV" I would be suspicious. For one thing, if these aliens were "passing through our solar system" then they would be less than a thousand years ahead of us. And they would be able to decipher our TV broadcasts (now 40 light-years out) and speak English. If they were a million years ahead of us, they would just appear and disappear whenever they wanted. And if they were that advanced, they could use their advanced knowledge to communicate in terms we could understand. It is true that it would take us a while to understand some of their concepts, but they would have no problem with ours.

I've always believed that when some space faring race of intelligent beings wants to contact us, they will. Until such time we have no chance of actually contacting intelligent aliens. THEY are in charge of that, not us. When they want to let us know they exist, they will. Until such time we are just going to fail at every attempt we make to find intelligent life.

Given the reasonable assumption that any space-faring aliens will be more technologically advanced than us, this is a reasonable conclusion. However, you are also assuming that they do not share the most obvious attribute of life: it spreads into every possible niche it possibly can--adapting as necessary. You need to discover a reason why *NO* technologically advanced aliens have already taken over this solar system. This is the essence of the Fermi Paradox. From everything we know about stars, chemistry, and biology, alls of the intelligent species in this galaxy should be here by now (actually, hundreds of millions of years ago). But they aren't. So what happened to them? What big filter stopped them? Because we are going to face that filter in our future, and if nothing else, that should scare the living daylights of us.

Ultimately I believe is that our universe is teeming with life,and that such life exists in various states of evolution. Some older than us, some younger than us.

To hold such a belief, you must propose a solution to the Fermi Paradox, not to mention a realistic hypothesis for abiogenisis or panspermia. What are the filters that explain the Great Silence?

Once we have learned how to travel to other stars, the question of is there other life in the universe will be answered. Until that day comes, however, I expect all attempts to find life will be unsuccessful.

If intelligent beings millions of years more advanced than us are out there, they could easily hide. Maybe they already moved to another dimension. In either case, for all practical purposes we are alone, probably due to make a similar possibility in our future. Though it ought to be fairly easy to detect things like Dyson Rings and Matrioshka Brains, even with our primitive technology. In the foreseeable future (100 years), we should be able to build telescopes with the aperture of entire planets.

This is all just my opinion, and I could be wrong.

Of course you're wrong. Maybe not even wrong, which would be worse. But it's important to know *why* you're wrong. I'm sure that I'm wrong too, but nobody has been able to explain why I might be wrong. Maybe you can. The object of the game is to be less wrong by following the available evidence to the truth.

 

[Jabbadonut]

Yes. As Douglas Adams put it, "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."



I don't think you appreciate how much humans can comprehend.

True, we can't comprehend infinity, but given the time since the big bang, we *can* comprehend the size of the universe fairly easily: if the big bang occurred 4.3 billion years ago, and the expansion occurred at the speed of light (at most), then the universe is less than 4.3 billion light years across. Possibly twice that measured from the center, but there is so center,. That is where our comprehension starts going off the rail, but it's fine until then.



Yes and no.
What you are missing is how the the intelligent life gets there.

For example, Homo Sapiens lived in Africa for almost 300,000 years before we showed up in Americas 20,000 years ago. Not because we couldn't.

If you are implying that intelligent life will appear every where that it can survive (presumably through abiogenisis or panspermia and then evolution), then you are making some really big assumptions. Having a very big brain is metabolically quite expensive, and there are lots of difficult filter we had to survive in order to get to where we are now (and there are probably a number of huge ones ahead of us too!).

For example, what is necessary for tide pools and deep sea vents--places biologists usually mention as being necessary for providing the metabolic energy and the evolutionary pump for multicellularism? You need a very large moon not only to thin the crust (without the Moon we would be like Venus) for tectonic plates to happen (and deep sea vents to appear). Also, you also need that same large moon to cause tides (hence tide pools). Otherwise the environment is too static for anything to happen. The thing is, double planets like Earth and Luna are very rare.

There are at least a dozen other filters (some of which we don't know about), without which we would still be as dumb as fish. You can't have a water world because it's kindof difficult to start fires. More to the point, why are killer whales so much smarter than sharks? Does intelligence depend on having dry land? You need to do persistence hunting to develop intelligence, not only so that hunters must become intelligent enough to always chase the same individual prey, but also so that the running females small hips force the young to be born prematurely--enabling environment (such as culture and technology) to play a larger role compared to instincts.



That would seem a reasonable assumption, though what you mean by "different" is unclear.

There are many instances of parallel evolution here on Earth; it would also be reasonable to for intelligent life to be quite similar to us.
Artificial Intelligence pioneer Marvin Minsky proposed that we would have a relatively easy time communicating with intelligent aliens because mathematics and physics is the same across the universe, and provides the common ground for understanding. Theologians like Thomas Aquinas who share a similar belief in objective truth would probably agree (though in this case the objective subject matter is different).



If it's "made of TV" I would be suspicious. For one thing, if these aliens were "passing through our solar system" then they would be less than a thousand years ahead of us. And they would be able to decipher our TV broadcasts (now 40 light-years out) and speak English. If they were a million years ahead of us, they would just appear and disappear whenever they wanted. And if they were that advanced, they could use their advanced knowledge to communicate in terms we could understand. It is true that it would take us a while to understand some of their concepts, but they would have no problem with ours.



Given the reasonable assumption that any space-faring aliens will be more technologically advanced than us, this is a reasonable conclusion. However, you are also assuming that they do not share the most obvious attribute of life: it spreads into every possible niche it possibly can--adapting as necessary. You need to discover a reason why *NO* technologically advanced aliens have already taken over this solar system. This is the essence of the Fermi Paradox. From everything we know about stars, chemistry, and biology, alls of the intelligent species in this galaxy should be here by now (actually, hundreds of millions of years ago). But they aren't. So what happened to them? What big filter stopped them? Because we are going to face that filter in our future, and if nothing else, that should scare the living daylights of us.



To hold such a belief, you must propose a solution to the Fermi Paradox, not to mention a realistic hypothesis for abiogenisis or panspermia. What are the filters that explain the Great Silence?



If intelligent beings millions of years more advanced than us are out there, they could easily hide. Maybe they already moved to another dimension. In either case, for all practical purposes we are alone, probably due to make a similar possibility in our future. Though it ought to be fairly easy to detect things like Dyson Rings and Matrioshka Brains, even with our primitive technology. In the foreseeable future (100 years), we should be able to build telescopes with the aperture of entire planets.



Of course you're wrong. Maybe not even wrong, which would be worse. But it's important to know *why* you're wrong. I'm sure that I'm wrong too, but nobody has been able to explain why I might be wrong. Maybe you can. The object of the game is to be less wrong by following the available evidence to the truth.

You can argue all day long and it won't change anything. Open your mind.