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Layman here. This is the first I'm hearing that - it is the first time we detect a planet outside our galaxy. Can someone remind me how it comes to pass that t

Layman here. This is the first I'm hearing that - it is the first time we detect a planet outside our galaxy. Can someone remind me how it comes to pass that there are people in the scientific community who believe we are the only "intelligent" life form? (I know there are a few theories that explain why there aren't any, whose names escape me at the moment) It boggles my mind.

ajkjk 6y ago
The idea that we are, or are not, the only intelligent life form is an opinion, not a scientific theory in the formal sense of the word -- there is no evidence either way. People's opinions on it are just that, opinions, and scientists can be wrong or biased like anyone else. Statistical arguments, such as the Drake equation, strongly suggest that there is other life. The Anthropic Principle and the 'Great Filter' idea suggest reasons why there might not be. (https://en.wikipedia.org/wiki/Great_Filter https://en.wikipedia.org/wiki/Great_Filter)
- enkid 6y ago
  Does the Drake equation really strongly suggest there is other life? It seems to me there are still so many unknown variables that we can't make that determination at this point. Sure, some people have some intuition about it, but intuition is often (normally...?) wrong.
  - the8472 6y ago
    https://arxiv.org/abs/1806.02404 https://arxiv.org/abs/1806.02404
    - enkid 6y ago
      Looks like an interesting paper. In fact, it looks like it's saying basically the same thing I'm saying, we really don't know enough to make assertions about the likelihood of finding intelligent life at this point.
  - pfraze 6y ago
    It’s not a question of intuition. The Drake equation tries to make a conservative calculation of the factors involved in the formation of life. As you might imagine, those odds are extremely low. It then multiplies those odds against the number of expected candidate planets. Space is so mind-blowingly big that the result becomes extremely likely. Again, that assumes no limiting phenomena, which is what things like great filter theory posit
    - enkid 6y ago
      There are multiple areas of the Drake equation that we have either no or only one data point on: - Number of planets that can support life that will develop life - Number of planets that have developed life that will develop intelligent life - Fraction of intelligent life that will develop the technology to transmit signals of their existence - The length of time that those signals will be sent We only know anything about any of these processes on one planet. That means we are guessing when we put numbers to these factors. We don't know if these numbers are 1 in 100 or 1 in a trillion. That's what I mean by having intuition but not really having evidence.
      - pfraze 6y ago
        Sure, my counter is just that the Drake equation uses conservative probabilities on those questions. Even pessimistic answers to those questions turn into optimistic projections given the scale of the universe. We’re obviously discussing a bunch of unknowns, but my intuition was actually more pessimistic until I saw what the Drake equation observed
        ladberg 6y ago
        The problem is that we don't know if the "conservative probabilities" are actually conservative. There is only a single planet in the Goldilocks zone that we for sure contains or doesn't contain life. Imagine if someone showed you a rock in the forest with some lichen in weird pattern and asked you for a "conservative estimate" for how many other rocks on Earth had that same pattern. Maybe pattern is common, but maybe it's something incredibly unique that no other rock has. Because you can't ever look at a different rock, there is no reasonable answer.
will123195 6y ago
https://en.m.wikipedia.org/wiki/Fermi_paradox https://en.m.wikipedia.org/wiki/Fermi_paradox
Voloskaya 6y ago
> Can someone remind me how it comes to pass that there are people in the scientific community who believe we are the only "intelligent" life form? Because the universe is 15+ bilions of years old. Considering the speed at which we have evolved technologically, assuming life developed on earth in a perfectly average way (i.e. we are not special), and given that our solar system didn't appear particularily early, there should be a lot of much older civilizations (and thus much more advanced) around, even within our galaxy. Thus, the fact that we are unable to detect any signal from even a single other civilization is quite puzzling, we should be inundated by those signals. P.S: I don't know if many people in the scientific community really believe that we are the only ones out there, more so that intelligent life forms could be extremely rare.
- asou 6y ago
  What if Radio waves simply don't work the same on other planets . Or one of the first things civilizations figure out is to not broadcast your presence. Or ... Everyone else in the universe found peace by stopping at the stone age , before all this social media made us miserable. It's just conjecture, but I imagine aliens exist, but they might not even be in a form re recognize.
  - enkid 6y ago
    Well, to pick some nits, if radio waves didn't work the same way, that would be a pretty fundamental shift in physics, to the point of throwing all our assumptions out the window about our observational evidence.
    - asou 6y ago
      We're assuming they communicate the same way we would. I'll make up something scifi like. On planet x they use short term Seismic wave to move data around. How would we on earth ever pick that up
- willis936 6y ago
  > we are not special This is a very common trap. I see this way of thinking applied to the presence of life on Earth all the time. It’s gilded in the Drake equation. It is very possible that Earth is the only planet in the galaxy or even universe with life on it. As the most powerful species on that planet, we should make responsible decisions. There is zero evidence, or even a compelling argument using existing data, that contradicts this possibility.
deleted 6y ago
[deleted]
godelski 6y ago
I don't think anyone in the astrophysics community thinks we're alone. But the physics also suggests that unless they are extremely common it's unlikely that we'll ever detect any (let alone meet any). So practically we are alone. Outside the astrophysics community the majority of scientists I know also believe in life but similarly don't think we will detect/meet them. But there are some that don't believe (I don't know a single person in hard science that thinks we're alone but I do know engineers and those in soft sciences that reject the notion).
- lovemenot 6y ago
  This doesn't refute what you said. Cool Worlds is an excellent YouTube channel presented by an Astrophysics prof. He recently gave an even-handed presentation of both sides, but on balance, he comes down slightly on the side of Life is unique to this planet. https://youtu.be/iLbbpRYRW5Y https://youtu.be/iLbbpRYRW5Y
yyyk 6y ago
Because there are a lot of other things necessary for life. Usually we get the 'planet X may be suitable for life' PR news item first, and later in the scientific press we find out quietly 'planet X is awash in deadly gamma radiation, and the tectonics are such that there's a richter scale 13 quake every week'. It turns out that when taking into account all known factors, us being alone is a nontrivial possibility: https://arxiv.org/pdf/1806.02404.pdf https://arxiv.org/pdf/1806.02404.pdf
thordenmark 6y ago
We only have one data point. Earth. There is not enough information to do any kind of real statistical analysis. All we are left with is gut instinct. And that's not science.
JumpCrisscross 6y ago
> Can someone remind me how it comes to pass that there are people in the scientific community who believe we are the only "intelligent" life form? Sure. I’m a strong-form rare Earther. Interstellar pan-spermia is possible but unlikely across large distances. Independent seeding is the only way a 14bn-year-old expanding universe 93 Gly in diameter proliferates with life. We don’t understand abiogenesis. All indications suggest it’s a difficult problem. The abundance of elements is set by the nuclear physics of stellar fusion and neutron star collision. Solvency further restricts biological chemistry. Given this, it seems likely that life in any form is quite rare. Then we have multicellular life. On Earth, this is a product of the fusion of mitochondria and bilipid-barrier cells. Consider the number of cells in Earth’s history. The eucharyotic union occurred once. That is improbable. I believe we will find scattered archae beyond our Solar System. (We may find single-celled life within it.) But complex multicellular life—let alone intelligence—takes so many variables perfectly aligning that it strikes me as vanishingly improbable. We must as a species confront the moral implications of possibly being the sole light of life in this universe. That’s an uncomfortable burden. I understand why we shy from it.
- hariguleria 6y ago
  It is an echo of the ‘centrist’ mindset. It was as difficult to understand that earth was not the center of the universe. Then our sun was not the center of the universe. Now that the human soul is not the center of all living things on earth. If life is a possibility then intelligence isn’t simply a matter of time. However, the bigger question is whether intelligence is the curse of life. Is intelligence self destructive by its very arrogance and nature. Just published an article ‘Beyond Drake- Earth 2.0’ as the foundation for this very question. You can google and find it. It’s the start of a journey and a path to this question.
  - saiya-jin 6y ago
    Its not about being the centre of anything... more like we had so much luck its unbelievable (stable sun, big planets cleaning asteroids, moon, magnetosphere etc.), and other life out there would quite a few more billions of years to get where we are. At least in this part of Milky way. And its entirely possible light speed is the limiting factor that can't be crossed. Hence the civilizations of distant galaxies will remain unknown to us, same as we to them.
jacobwilliamroy 6y ago
I'm still pissed about the number of people who refuse to acknowledge cetacean intelligence. Even ignoring the scientific studies performed by people like John C. Lilly, Karen Pryor and Kenneth Norris, just swimming with wild dolphins or humpback whales, it becomes clear that these creatures are at least as smart as us, probably smarter.
tsimionescu 6y ago
Think about it this way. The Earth today is not capable of sprouting life (abiogenesis). In fact, from the fossil record and genetic studies, the Earth has almost certainly been unable to form new life (out of un living substances I mean) for billions of years. Then, the same is true for multicellular life appearing from unicelular life. All of the living multi-cell organisms today seem to be descended from 1 common ancestor, 1 time that multicellular life has ever appeared in more than a billion years. So right now, the very basic needs for life to even start seem to be staggeringly unlikely. Even at the huge scales of planets in the universe, it could be that the chances we'll ever meet another civilization are un conceivably low. Of course, simple life could exist 'all over the place', and most scientists generally believe that. But life capable of interstellar communication like us may well be staggeringly rare in the universe. We'll probably know a lot more about this in the coming decades/century, as we'll hopefully be able to send probes to look for life on Mars, Europa, Venus and other potential candidates in the Solar System. Perhaps we'll even be able to create abiogenesis in the lab and be able to learn more about the possible requirements that way.
- leto_ii 6y ago
  > The Earth today is not capable of sprouting life (abiogenesis). In fact, from the fossil record and genetic studies, the Earth has almost certainly been unable to form new life (out of un living substances I mean) for billions of years. Playing devil's advocate for a bit, how do you know that existing life, honed by evolution, doesn't simply outcompete life that is continuously born abiogenetically in places like hydrothermal vents [1]? [1] https://en.m.wikipedia.org/wiki/Hydrothermal_vent https://en.m.wikipedia.org/wiki/Hydrothermal_vent
  - tsimionescu 6y ago
    Of course, we can't know for sure, but the fact that in all this time no other strain seems to have made it makes that theory implausible to me. To be fair though, there is A LOT of life on earth, so we can't discount the possibility that we'll find some forms of life that come from a different tree than us.

ajkjk 6y ago

The idea that we are, or are not, the only intelligent life form is an opinion, not a scientific theory in the formal sense of the word -- there is no evidence either way. People's opinions on it are just that, opinions, and scientists can be wrong or biased like anyone else. Statistical arguments, such as the Drake equation, strongly suggest that there is other life. The Anthropic Principle and the 'Great Filter' idea suggest reasons why there might not be. (https://en.wikipedia.org/wiki/Great_Filter https://en.wikipedia.org/wiki/Great_Filter)

enkid 6y ago
Does the Drake equation really strongly suggest there is other life? It seems to me there are still so many unknown variables that we can't make that determination at this point. Sure, some people have some intuition about it, but intuition is often (normally...?) wrong.
- the8472 6y ago
  https://arxiv.org/abs/1806.02404 https://arxiv.org/abs/1806.02404
  - enkid 6y ago
    Looks like an interesting paper. In fact, it looks like it's saying basically the same thing I'm saying, we really don't know enough to make assertions about the likelihood of finding intelligent life at this point.
- pfraze 6y ago
  It’s not a question of intuition. The Drake equation tries to make a conservative calculation of the factors involved in the formation of life. As you might imagine, those odds are extremely low. It then multiplies those odds against the number of expected candidate planets. Space is so mind-blowingly big that the result becomes extremely likely. Again, that assumes no limiting phenomena, which is what things like great filter theory posit
  - enkid 6y ago
    There are multiple areas of the Drake equation that we have either no or only one data point on: - Number of planets that can support life that will develop life - Number of planets that have developed life that will develop intelligent life - Fraction of intelligent life that will develop the technology to transmit signals of their existence - The length of time that those signals will be sent We only know anything about any of these processes on one planet. That means we are guessing when we put numbers to these factors. We don't know if these numbers are 1 in 100 or 1 in a trillion. That's what I mean by having intuition but not really having evidence.
    - pfraze 6y ago
      Sure, my counter is just that the Drake equation uses conservative probabilities on those questions. Even pessimistic answers to those questions turn into optimistic projections given the scale of the universe. We’re obviously discussing a bunch of unknowns, but my intuition was actually more pessimistic until I saw what the Drake equation observed
      - ladberg 6y ago
        The problem is that we don't know if the "conservative probabilities" are actually conservative. There is only a single planet in the Goldilocks zone that we for sure contains or doesn't contain life. Imagine if someone showed you a rock in the forest with some lichen in weird pattern and asked you for a "conservative estimate" for how many other rocks on Earth had that same pattern. Maybe pattern is common, but maybe it's something incredibly unique that no other rock has. Because you can't ever look at a different rock, there is no reasonable answer.

will123195 6y ago

https://en.m.wikipedia.org/wiki/Fermi_paradox https://en.m.wikipedia.org/wiki/Fermi_paradox

Voloskaya 6y ago

> Can someone remind me how it comes to pass that there are people in the scientific community who believe we are the only "intelligent" life form? Because the universe is 15+ bilions of years old. Considering the speed at which we have evolved technologically, assuming life developed on earth in a perfectly average way (i.e. we are not special), and given that our solar system didn't appear particularily early, there should be a lot of much older civilizations (and thus much more advanced) around, even within our galaxy. Thus, the fact that we are unable to detect any signal from even a single other civilization is quite puzzling, we should be inundated by those signals. P.S: I don't know if many people in the scientific community really believe that we are the only ones out there, more so that intelligent life forms could be extremely rare.

asou 6y ago
What if Radio waves simply don't work the same on other planets . Or one of the first things civilizations figure out is to not broadcast your presence. Or ... Everyone else in the universe found peace by stopping at the stone age , before all this social media made us miserable. It's just conjecture, but I imagine aliens exist, but they might not even be in a form re recognize.
- enkid 6y ago
  Well, to pick some nits, if radio waves didn't work the same way, that would be a pretty fundamental shift in physics, to the point of throwing all our assumptions out the window about our observational evidence.
  - asou 6y ago
    We're assuming they communicate the same way we would. I'll make up something scifi like. On planet x they use short term Seismic wave to move data around. How would we on earth ever pick that up
willis936 6y ago
> we are not special This is a very common trap. I see this way of thinking applied to the presence of life on Earth all the time. It’s gilded in the Drake equation. It is very possible that Earth is the only planet in the galaxy or even universe with life on it. As the most powerful species on that planet, we should make responsible decisions. There is zero evidence, or even a compelling argument using existing data, that contradicts this possibility.

deleted 6y ago

[deleted]

godelski 6y ago

I don't think anyone in the astrophysics community thinks we're alone. But the physics also suggests that unless they are extremely common it's unlikely that we'll ever detect any (let alone meet any). So practically we are alone. Outside the astrophysics community the majority of scientists I know also believe in life but similarly don't think we will detect/meet them. But there are some that don't believe (I don't know a single person in hard science that thinks we're alone but I do know engineers and those in soft sciences that reject the notion).

lovemenot 6y ago
This doesn't refute what you said. Cool Worlds is an excellent YouTube channel presented by an Astrophysics prof. He recently gave an even-handed presentation of both sides, but on balance, he comes down slightly on the side of Life is unique to this planet. https://youtu.be/iLbbpRYRW5Y https://youtu.be/iLbbpRYRW5Y

yyyk 6y ago

Because there are a lot of other things necessary for life. Usually we get the 'planet X may be suitable for life' PR news item first, and later in the scientific press we find out quietly 'planet X is awash in deadly gamma radiation, and the tectonics are such that there's a richter scale 13 quake every week'. It turns out that when taking into account all known factors, us being alone is a nontrivial possibility: https://arxiv.org/pdf/1806.02404.pdf https://arxiv.org/pdf/1806.02404.pdf

thordenmark 6y ago

We only have one data point. Earth. There is not enough information to do any kind of real statistical analysis. All we are left with is gut instinct. And that's not science.

JumpCrisscross 6y ago

> Can someone remind me how it comes to pass that there are people in the scientific community who believe we are the only "intelligent" life form? Sure. I’m a strong-form rare Earther. Interstellar pan-spermia is possible but unlikely across large distances. Independent seeding is the only way a 14bn-year-old expanding universe 93 Gly in diameter proliferates with life. We don’t understand abiogenesis. All indications suggest it’s a difficult problem. The abundance of elements is set by the nuclear physics of stellar fusion and neutron star collision. Solvency further restricts biological chemistry. Given this, it seems likely that life in any form is quite rare. Then we have multicellular life. On Earth, this is a product of the fusion of mitochondria and bilipid-barrier cells. Consider the number of cells in Earth’s history. The eucharyotic union occurred once. That is improbable. I believe we will find scattered archae beyond our Solar System. (We may find single-celled life within it.) But complex multicellular life—let alone intelligence—takes so many variables perfectly aligning that it strikes me as vanishingly improbable. We must as a species confront the moral implications of possibly being the sole light of life in this universe. That’s an uncomfortable burden. I understand why we shy from it.

hariguleria 6y ago
It is an echo of the ‘centrist’ mindset. It was as difficult to understand that earth was not the center of the universe. Then our sun was not the center of the universe. Now that the human soul is not the center of all living things on earth. If life is a possibility then intelligence isn’t simply a matter of time. However, the bigger question is whether intelligence is the curse of life. Is intelligence self destructive by its very arrogance and nature. Just published an article ‘Beyond Drake- Earth 2.0’ as the foundation for this very question. You can google and find it. It’s the start of a journey and a path to this question.
- saiya-jin 6y ago
  Its not about being the centre of anything... more like we had so much luck its unbelievable (stable sun, big planets cleaning asteroids, moon, magnetosphere etc.), and other life out there would quite a few more billions of years to get where we are. At least in this part of Milky way. And its entirely possible light speed is the limiting factor that can't be crossed. Hence the civilizations of distant galaxies will remain unknown to us, same as we to them.

jacobwilliamroy 6y ago

I'm still pissed about the number of people who refuse to acknowledge cetacean intelligence. Even ignoring the scientific studies performed by people like John C. Lilly, Karen Pryor and Kenneth Norris, just swimming with wild dolphins or humpback whales, it becomes clear that these creatures are at least as smart as us, probably smarter.

tsimionescu 6y ago

Think about it this way. The Earth today is not capable of sprouting life (abiogenesis). In fact, from the fossil record and genetic studies, the Earth has almost certainly been unable to form new life (out of un living substances I mean) for billions of years. Then, the same is true for multicellular life appearing from unicelular life. All of the living multi-cell organisms today seem to be descended from 1 common ancestor, 1 time that multicellular life has ever appeared in more than a billion years. So right now, the very basic needs for life to even start seem to be staggeringly unlikely. Even at the huge scales of planets in the universe, it could be that the chances we'll ever meet another civilization are un conceivably low. Of course, simple life could exist 'all over the place', and most scientists generally believe that. But life capable of interstellar communication like us may well be staggeringly rare in the universe. We'll probably know a lot more about this in the coming decades/century, as we'll hopefully be able to send probes to look for life on Mars, Europa, Venus and other potential candidates in the Solar System. Perhaps we'll even be able to create abiogenesis in the lab and be able to learn more about the possible requirements that way.

leto_ii 6y ago
> The Earth today is not capable of sprouting life (abiogenesis). In fact, from the fossil record and genetic studies, the Earth has almost certainly been unable to form new life (out of un living substances I mean) for billions of years. Playing devil's advocate for a bit, how do you know that existing life, honed by evolution, doesn't simply outcompete life that is continuously born abiogenetically in places like hydrothermal vents [1]? [1] https://en.m.wikipedia.org/wiki/Hydrothermal_vent https://en.m.wikipedia.org/wiki/Hydrothermal_vent
- tsimionescu 6y ago
  Of course, we can't know for sure, but the fact that in all this time no other strain seems to have made it makes that theory implausible to me. To be fair though, there is A LOT of life on earth, so we can't discount the possibility that we'll find some forms of life that come from a different tree than us.