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The big argument against intelligent life being common (and us not being unique) is the existence of stars. No civilization more advanced than us is going to le

The big argument against intelligent life being common (and us not being unique) is the existence of stars. No civilization more advanced than us is going to let stupendous amounts of energy go to waste in the form of star light. If you assume von Neumann probes and Dyson spheres are possible, then star light is incompatible with the existence of advanced technology. While life appeared very early in the history of the earth, technologically advanced life took billions of years to evolve. You require a planet with an extraordinarily stable climate to allow a technological society to evolve and I predict this is the filter. Just one factor contributing to this stability is the need for a very large moon to keep the axis of rotation stable over billion of years. If the Earth didn't have its moon the Earth's axis would tip over creating massive climatic change. The more we look at the universe the more unlikely the stability of Earth's climate looks.

mixmastamyk 10y ago
> the need for a very large moon to keep the axis of rotation stable First I've heard of this, do you have any more information?
- danieltillett 10y ago
  Yes there is lots of information on this out there [1-3]. Really the moon is very, very, very unusual. 1. http://www.nature.com/nature/journal/v361/n6413/abs/361615a0.html http://www.nature.com/nature/journal/v361/n6413/abs/361615a0... 2. http://www.astrobio.net/news-exclusive/the-odds-for-life-on-a-moonless-earth/ http://www.astrobio.net/news-exclusive/the-odds-for-life-on-... 3. http://www.space.com/12464-earth-moon-unique-solar-system-universe.html http://www.space.com/12464-earth-moon-unique-solar-system-un...
Falcon9 10y ago
From what little I understand, a Dyson Sphere would require so much material in terms of heavy elements that you'd have a great deal of trouble building a significant number of them even if you were raiding the entire universe for these materials. But like I said, I understand very little (and would love clarification).
- danieltillett 10y ago
  There are alternatives to a classical Dyson sphere (Dyson bubble is one) that can be constructed to capture all the energy released by a star and which do not require much material [1]. I actually think you would use a series of nested Dyson bubbles to capture the energy via a cascade much like the electron transport chain [2] uses a multi-protein redox cascade to capture the energy of metabolism. 1. https://en.wikipedia.org/wiki/Dyson_sphere https://en.wikipedia.org/wiki/Dyson_sphere 2. https://en.wikipedia.org/wiki/Electron_transport_chain https://en.wikipedia.org/wiki/Electron_transport_chain
agentgt 10y ago
> The big argument against intelligent life being common (and us not being unique) is the existence of stars. No civilization more advanced than us is going to let stupendous amounts of energy go to waste in the form of star light. If you assume von Neumann probes and Dyson spheres are possible, then star light is incompatible with the existence of advanced technology. What about undetected energy aka dark energy. > Just one factor contributing to this stability is the need for a very large moon to keep the axis of rotation stable over billion of years. If the Earth didn't have its moon the Earth's axis would tip over creating massive climatic change. The more we look at the universe the more unlikely the stability of Earth's climate looks. I have heard this argument but I don't buy it compared to the need for asteroid protection. Things can get various like climate living underground/water. One of the critical things about our solar system that made life happen with out having a mega earth planet with crushing gravity is the presence of Jupiter and Saturn. Jupiter and Saturn were in our solar system at the right place and right time. This theory is called the "Grand Tack" [1] and was recently covered in Scientific America. Needless to say Jupiter continuously protects us from asteroids and various other objects from colliding with us on a continuous basis and not our axis. [2] Continuous asteroid collisions vaporize oceans and destroy atmospheres along with other various debilitating things. [1]: https://en.wikipedia.org/wiki/Grand_tack_hypothesis https://en.wikipedia.org/wiki/Grand_tack_hypothesis [2]: http://imgur.com/gallery/DCLp8yc http://imgur.com/gallery/DCLp8yc
- danieltillett 10y ago
  Yes the presence and size of Jupiter and Saturn are another unlikely factor contributing to extreme stability of the Earth’s climate. Another one is earth seems to have escaped being exposed to a supernova going off very nearby [1]. 1. https://en.wikipedia.org/wiki/Gamma-ray_burst https://en.wikipedia.org/wiki/Gamma-ray_burst
Udo 10y ago
> The big argument against intelligent life being common (and us not being unique) Those are two different things. "Common" is something up for interpretation, especially with the huge numbers concerned. Intelligence being uncommon could still mean hundreds of civilizations active in the galaxy right now. The term "uncommon" allows us to have somewhat meaningful discussions about probabilities. "Unique" on the other hand is an unsubstantiated, almost supernatural, claim of us being the only intelligence in existence anywhere. > No civilization more advanced than us is going to let stupendous amounts of energy go to waste in the form of star light. That is also a big claim. Yes, a civilization pursuing a maximum energy strategy would probably harness stars, at least from our current technological perspective that seems reasonable. However, very few people looking for signs of this would actually claim that all civilizations more advanced than us must do this. So originally at least, this hypothesis was proposed under the more reasonable premise that for purposes of detection it would be enough if one such civilization pursued this strategy. Again, the claim that all of them would necessarily do this seems needlessly extremist. > You require a planet with an extraordinarily stable climate to allow a technological society to evolve and I predict this is the filter. There is a good chance you're at least somewhat correct, but then again I can easily imagine planets with a way more stable history than Earth had. A sample size of one is always going to be a problem, especially if you lack the means of even knowing what to look for. Making absolutist claims a priori seems to me like an argument to stop looking. Historically, claims of uniqueness and specialness have had a tendency to be wrong. It seems to me like a good default stance is to assume that whatever we see in front of us has a chance of occurring that is significantly higher than zero.
- danieltillett 10y ago
  You don’t need most advanced civilisations to want to spread, just one. The first one that choose to spread will occupy the universe and capture all the energy that the stars are currently emitting into space. The more we learn about other planets the more unusual Earth looks from a climatic stability perspective. There really is a good chance that Earth is unique in its level of stability - at least within the visible universe.
  - 10y ago
Terr_ 10y ago
What if they've got something more-convenient or powerful than going around messing with each star? I just imagine an intelligent beaver: "There can't be any other intelligence out there, just look at all these rivers and streams!" Meanwhile, humans are enjoying fusion-power and will take a little while to notice suspiciously-well-engineered beaver dams showing up everywhere.
- Udo 10y ago
  Exactly. I like this analogy especially because our needs as a more advanced civilization are drastically different from the function performed by beaver dams. It's not even about energy per se. We could dam all the streams, but that's not a meaningful pursuit given our interests. Likewise, wondering about damming all the stars assumes that solar energy requirements are both the bottleneck and the ultimate purpose of advanced civilizations.
  - WildUtah 10y ago
    "We could dam all the streams, but that's not a meaningful pursuit given our interests" Could you please explain that to the World Bank and governments in Africa, SE Asia, China, and Oceania that insist on damning the last free-flowing rivers on Earth?
    - Terr_ 10y ago
      Rivers are bigger than streams. When it comes to hydroelectric power and titanic concrete structures, we look for very different water-situations than beavers do.
      - danieltillett 10y ago
        Humans dam lots of small streams too for agricultural and recreational uses. They don't get much news, but if you look at aerial surveys of places where people live you will see lots of small dams.
  - adrianN 10y ago
Retra 10y ago
>No civilization more advanced than us is going to let stupendous amounts of energy go to waste in the form of star light. Isn't this implying that any civilization more advanced than us must be able to take advantage of much more of a star's energy? Like say... humans in 6 months? I see no reason for the band of possible civilizations between current humans and Dyson sphere building ones must be narrow at all. In fact, the vast majority of all possible civilizations might lie in that band, simply because it might be objectively impossible to actually build a Dyson sphere.
- danieltillett 10y ago
  I did assume that it was possible to build a Dyson sphere, or some structure functionally equivalent. If you have von Neumann probes then Dyson spheres are by comparison simple.
  - Retra 10y ago
    Even a functionally equivalent system will have problems. For one, if you're absorbing a significant portion of the sun's radiation, that's going to generate a lot of heat that you've got to dissipate somehow. Then you've got to transport that energy in a way that's more efficient than the way the sun is already doing it. Then you've got the logistics problem: it's easy to build a modern CPU (for example) if you're assuming all the infrastructure already exists. If you're assuming it doesn't, it takes much more energy to produce the first one than any subsequent ones. And it may be the case that in order to build an energy-positive Dyson sphere/von Neumann probe network you'd need to already have consumed a couple stars prior. And to do anything on that scale, you're already talking about coordinating activities across multiple planets or solar systems, which comes with it's own massive overhead. There's a lot of ground to cover between burning fossil fuels and consuming stars, and little reason to assume a successful civilization must do the latter. You could potentially go quite a while syphoning fuel off a gas Giant, for example.
Joof 10y ago
Why can't they be brilliant and have no interest in harnessing that amount of energy for whatever purpose.
- danieltillett 10y ago
  99.999% of all civilisations could have no interest in doing this, but all it takes is one in the universe and all the stars will be converted (over time).
brador 10y ago
Could Black holes be Dyson spheres?
- danieltillett 10y ago
  No. Black holes could be tapped as a source of energy though if you have an advanced enough technology.
cgriswald 10y ago
> No civilization more advanced than us is going to let stupendous amounts of energy go to waste in the form of star light. Unless it is not worth the trade off. Material is rare and might be more useful for data storage than for harnessing energy. It's not difficult to imagine a civilization that consists of a single Dyson swarm, perhaps using the star as both an energy source and propulsion system. When they use up the star, they can move on to another star. Detectable, but just barely, and only if we happen to look in the right direction.
corecoder 10y ago
I don't get this argument. Let's just posit that every single advanced civilization ends up building lots and lots of Dyson spheres (which I'm totally unconvinced of). Now, can you prove that there are no such spheres out there? No, you can't. You can only prove that a whole lot of stars have no sphere, but maybe we suck at detecting them and there's one right next to us. The only conclusion the argument draws if that advanced aliens are not yet nearly finished enclosing all the stars in spheres, and you might try to determine an upper limit to the rate of stars with Dyson spheres without us noticing.
- danieltillett 10y ago
  The argument is once you have one civilisation that can create von Neumann probes [1] then that civilisation will spread through the universe wrapping each star in a Dyson sphere [2] that will capture all the light. It only takes one civilisation in the universe to do this and all stars will cease to shine. The fact that we can see stars in the night sky means that they don’t have Dyson spheres around them hence there are not civilisations ahead of us - at least within the visible universe. 1. https://en.wikipedia.org/wiki/Self-replicating_spacecraft https://en.wikipedia.org/wiki/Self-replicating_spacecraft 2. https://en.wikipedia.org/wiki/Dyson_sphere https://en.wikipedia.org/wiki/Dyson_sphere
  - corecoder 10y ago
    Sure, but are we sure these probes are instantaneous? What if it takes more than zero time to build a Dyson sphere? As I said earlier, you're only proving that they have been building spheres for less time than it takes to finish up the whole universe, which they say is big.
    - danieltillett 10y ago
      The probe’s spread and and dyson sphere building does not need to be instantaneous, just that it had to have happened in the past. For example, if we were to create von Neumann probes and have them spread across the galaxy, it would take less than 100,000 years for the probes to reach every star. When you compare this to how long it took for our civilisation to evolve on Earth it is a blink of an eye. An interesting thought is if a new von Neumann spewing civilisation arose in the galaxy we would not have much warning before it reached us. The probes would be travelling just behind the light front and so would reach us only a little before the information that the stars between the probes origin and us went out. About the only way you could detect such an event is to look at very distant galaxies for examples that had spherical chunk taken out of them. I should get around to writing this all up in a blog post because it is such an interesting topic :)
WildUtah 10y ago
"No civilization more advanced than us is going to let stupendous amounts of energy go to waste in the form of star light." Any civilisation advanced enough to harvest dark energy isn't going to bother with backwards, inefficient starlight. And any civilisation that has found the loopholes in the Second Law of Thermodynamics isn't going to waste time dealing with barbaric resources like dark energy.
- danieltillett 10y ago
  If you assume the laws of physics hold even for advanced civilisation then they are not going to be able to find a loophole in the second law of thermodynamics :) Even if you assume that dark energy can be harvested then any advanced civilisation is still going to be energy constrained - Bremmermann's limit far exceeds any energy that can be harvested from dark energy [1]. 1. https://en.wikipedia.org/wiki/Bremermann%27s_limit https://en.wikipedia.org/wiki/Bremermann%27s_limit
  - WildUtah 10y ago
    Advanced civilizations with a constructive proof that P=NP don't need all that much compute power.

mixmastamyk 10y ago

> the need for a very large moon to keep the axis of rotation stable First I've heard of this, do you have any more information?

danieltillett 10y ago
Yes there is lots of information on this out there [1-3]. Really the moon is very, very, very unusual. 1. http://www.nature.com/nature/journal/v361/n6413/abs/361615a0.html http://www.nature.com/nature/journal/v361/n6413/abs/361615a0... 2. http://www.astrobio.net/news-exclusive/the-odds-for-life-on-a-moonless-earth/ http://www.astrobio.net/news-exclusive/the-odds-for-life-on-... 3. http://www.space.com/12464-earth-moon-unique-solar-system-universe.html http://www.space.com/12464-earth-moon-unique-solar-system-un...

Falcon9 10y ago

From what little I understand, a Dyson Sphere would require so much material in terms of heavy elements that you'd have a great deal of trouble building a significant number of them even if you were raiding the entire universe for these materials. But like I said, I understand very little (and would love clarification).

danieltillett 10y ago
There are alternatives to a classical Dyson sphere (Dyson bubble is one) that can be constructed to capture all the energy released by a star and which do not require much material [1]. I actually think you would use a series of nested Dyson bubbles to capture the energy via a cascade much like the electron transport chain [2] uses a multi-protein redox cascade to capture the energy of metabolism. 1. https://en.wikipedia.org/wiki/Dyson_sphere https://en.wikipedia.org/wiki/Dyson_sphere 2. https://en.wikipedia.org/wiki/Electron_transport_chain https://en.wikipedia.org/wiki/Electron_transport_chain

agentgt 10y ago

> The big argument against intelligent life being common (and us not being unique) is the existence of stars. No civilization more advanced than us is going to let stupendous amounts of energy go to waste in the form of star light. If you assume von Neumann probes and Dyson spheres are possible, then star light is incompatible with the existence of advanced technology. What about undetected energy aka dark energy. > Just one factor contributing to this stability is the need for a very large moon to keep the axis of rotation stable over billion of years. If the Earth didn't have its moon the Earth's axis would tip over creating massive climatic change. The more we look at the universe the more unlikely the stability of Earth's climate looks. I have heard this argument but I don't buy it compared to the need for asteroid protection. Things can get various like climate living underground/water. One of the critical things about our solar system that made life happen with out having a mega earth planet with crushing gravity is the presence of Jupiter and Saturn. Jupiter and Saturn were in our solar system at the right place and right time. This theory is called the "Grand Tack" [1] and was recently covered in Scientific America. Needless to say Jupiter continuously protects us from asteroids and various other objects from colliding with us on a continuous basis and not our axis. [2] Continuous asteroid collisions vaporize oceans and destroy atmospheres along with other various debilitating things. [1]: https://en.wikipedia.org/wiki/Grand_tack_hypothesis https://en.wikipedia.org/wiki/Grand_tack_hypothesis [2]: http://imgur.com/gallery/DCLp8yc http://imgur.com/gallery/DCLp8yc

danieltillett 10y ago
Yes the presence and size of Jupiter and Saturn are another unlikely factor contributing to extreme stability of the Earth’s climate. Another one is earth seems to have escaped being exposed to a supernova going off very nearby [1]. 1. https://en.wikipedia.org/wiki/Gamma-ray_burst https://en.wikipedia.org/wiki/Gamma-ray_burst

Udo 10y ago

> The big argument against intelligent life being common (and us not being unique) Those are two different things. "Common" is something up for interpretation, especially with the huge numbers concerned. Intelligence being uncommon could still mean hundreds of civilizations active in the galaxy right now. The term "uncommon" allows us to have somewhat meaningful discussions about probabilities. "Unique" on the other hand is an unsubstantiated, almost supernatural, claim of us being the only intelligence in existence anywhere. > No civilization more advanced than us is going to let stupendous amounts of energy go to waste in the form of star light. That is also a big claim. Yes, a civilization pursuing a maximum energy strategy would probably harness stars, at least from our current technological perspective that seems reasonable. However, very few people looking for signs of this would actually claim that all civilizations more advanced than us must do this. So originally at least, this hypothesis was proposed under the more reasonable premise that for purposes of detection it would be enough if one such civilization pursued this strategy. Again, the claim that all of them would necessarily do this seems needlessly extremist. > You require a planet with an extraordinarily stable climate to allow a technological society to evolve and I predict this is the filter. There is a good chance you're at least somewhat correct, but then again I can easily imagine planets with a way more stable history than Earth had. A sample size of one is always going to be a problem, especially if you lack the means of even knowing what to look for. Making absolutist claims a priori seems to me like an argument to stop looking. Historically, claims of uniqueness and specialness have had a tendency to be wrong. It seems to me like a good default stance is to assume that whatever we see in front of us has a chance of occurring that is significantly higher than zero.

danieltillett 10y ago
You don’t need most advanced civilisations to want to spread, just one. The first one that choose to spread will occupy the universe and capture all the energy that the stars are currently emitting into space. The more we learn about other planets the more unusual Earth looks from a climatic stability perspective. There really is a good chance that Earth is unique in its level of stability - at least within the visible universe.
- 10y ago

Terr_ 10y ago

What if they've got something more-convenient or powerful than going around messing with each star? I just imagine an intelligent beaver: "There can't be any other intelligence out there, just look at all these rivers and streams!" Meanwhile, humans are enjoying fusion-power and will take a little while to notice suspiciously-well-engineered beaver dams showing up everywhere.

Udo 10y ago
Exactly. I like this analogy especially because our needs as a more advanced civilization are drastically different from the function performed by beaver dams. It's not even about energy per se. We could dam all the streams, but that's not a meaningful pursuit given our interests. Likewise, wondering about damming all the stars assumes that solar energy requirements are both the bottleneck and the ultimate purpose of advanced civilizations.
- WildUtah 10y ago
  "We could dam all the streams, but that's not a meaningful pursuit given our interests" Could you please explain that to the World Bank and governments in Africa, SE Asia, China, and Oceania that insist on damning the last free-flowing rivers on Earth?
  - Terr_ 10y ago
    Rivers are bigger than streams. When it comes to hydroelectric power and titanic concrete structures, we look for very different water-situations than beavers do.
    - danieltillett 10y ago
      Humans dam lots of small streams too for agricultural and recreational uses. They don't get much news, but if you look at aerial surveys of places where people live you will see lots of small dams.
- adrianN 10y ago

Retra 10y ago

>No civilization more advanced than us is going to let stupendous amounts of energy go to waste in the form of star light. Isn't this implying that any civilization more advanced than us must be able to take advantage of much more of a star's energy? Like say... humans in 6 months? I see no reason for the band of possible civilizations between current humans and Dyson sphere building ones must be narrow at all. In fact, the vast majority of all possible civilizations might lie in that band, simply because it might be objectively impossible to actually build a Dyson sphere.

danieltillett 10y ago
I did assume that it was possible to build a Dyson sphere, or some structure functionally equivalent. If you have von Neumann probes then Dyson spheres are by comparison simple.
- Retra 10y ago
  Even a functionally equivalent system will have problems. For one, if you're absorbing a significant portion of the sun's radiation, that's going to generate a lot of heat that you've got to dissipate somehow. Then you've got to transport that energy in a way that's more efficient than the way the sun is already doing it. Then you've got the logistics problem: it's easy to build a modern CPU (for example) if you're assuming all the infrastructure already exists. If you're assuming it doesn't, it takes much more energy to produce the first one than any subsequent ones. And it may be the case that in order to build an energy-positive Dyson sphere/von Neumann probe network you'd need to already have consumed a couple stars prior. And to do anything on that scale, you're already talking about coordinating activities across multiple planets or solar systems, which comes with it's own massive overhead. There's a lot of ground to cover between burning fossil fuels and consuming stars, and little reason to assume a successful civilization must do the latter. You could potentially go quite a while syphoning fuel off a gas Giant, for example.

Joof 10y ago

Why can't they be brilliant and have no interest in harnessing that amount of energy for whatever purpose.

danieltillett 10y ago
99.999% of all civilisations could have no interest in doing this, but all it takes is one in the universe and all the stars will be converted (over time).

brador 10y ago

Could Black holes be Dyson spheres?

danieltillett 10y ago
No. Black holes could be tapped as a source of energy though if you have an advanced enough technology.

cgriswald 10y ago

> No civilization more advanced than us is going to let stupendous amounts of energy go to waste in the form of star light. Unless it is not worth the trade off. Material is rare and might be more useful for data storage than for harnessing energy. It's not difficult to imagine a civilization that consists of a single Dyson swarm, perhaps using the star as both an energy source and propulsion system. When they use up the star, they can move on to another star. Detectable, but just barely, and only if we happen to look in the right direction.

corecoder 10y ago

I don't get this argument. Let's just posit that every single advanced civilization ends up building lots and lots of Dyson spheres (which I'm totally unconvinced of). Now, can you prove that there are no such spheres out there? No, you can't. You can only prove that a whole lot of stars have no sphere, but maybe we suck at detecting them and there's one right next to us. The only conclusion the argument draws if that advanced aliens are not yet nearly finished enclosing all the stars in spheres, and you might try to determine an upper limit to the rate of stars with Dyson spheres without us noticing.

danieltillett 10y ago
The argument is once you have one civilisation that can create von Neumann probes [1] then that civilisation will spread through the universe wrapping each star in a Dyson sphere [2] that will capture all the light. It only takes one civilisation in the universe to do this and all stars will cease to shine. The fact that we can see stars in the night sky means that they don’t have Dyson spheres around them hence there are not civilisations ahead of us - at least within the visible universe. 1. https://en.wikipedia.org/wiki/Self-replicating_spacecraft https://en.wikipedia.org/wiki/Self-replicating_spacecraft 2. https://en.wikipedia.org/wiki/Dyson_sphere https://en.wikipedia.org/wiki/Dyson_sphere
- corecoder 10y ago
  Sure, but are we sure these probes are instantaneous? What if it takes more than zero time to build a Dyson sphere? As I said earlier, you're only proving that they have been building spheres for less time than it takes to finish up the whole universe, which they say is big.
  - danieltillett 10y ago
    The probe’s spread and and dyson sphere building does not need to be instantaneous, just that it had to have happened in the past. For example, if we were to create von Neumann probes and have them spread across the galaxy, it would take less than 100,000 years for the probes to reach every star. When you compare this to how long it took for our civilisation to evolve on Earth it is a blink of an eye. An interesting thought is if a new von Neumann spewing civilisation arose in the galaxy we would not have much warning before it reached us. The probes would be travelling just behind the light front and so would reach us only a little before the information that the stars between the probes origin and us went out. About the only way you could detect such an event is to look at very distant galaxies for examples that had spherical chunk taken out of them. I should get around to writing this all up in a blog post because it is such an interesting topic :)

WildUtah 10y ago

"No civilization more advanced than us is going to let stupendous amounts of energy go to waste in the form of star light." Any civilisation advanced enough to harvest dark energy isn't going to bother with backwards, inefficient starlight. And any civilisation that has found the loopholes in the Second Law of Thermodynamics isn't going to waste time dealing with barbaric resources like dark energy.

danieltillett 10y ago
If you assume the laws of physics hold even for advanced civilisation then they are not going to be able to find a loophole in the second law of thermodynamics :) Even if you assume that dark energy can be harvested then any advanced civilisation is still going to be energy constrained - Bremmermann's limit far exceeds any energy that can be harvested from dark energy [1]. 1. https://en.wikipedia.org/wiki/Bremermann%27s_limit https://en.wikipedia.org/wiki/Bremermann%27s_limit
- WildUtah 10y ago
  Advanced civilizations with a constructive proof that P=NP don't need all that much compute power.