3 ms·

Focusing on radio communications for SETI purposes and as a solution to the Fermi Paradox I find to be incredibly outdated thinking. Let me summarize: 1. Plane

by cletus 4y ago

Focusing on radio communications for SETI purposes and as a solution to the Fermi Paradox I find to be incredibly outdated thinking. Let me summarize: 1. Planets are incredibly inefficient in creating living area per unit mass; 2. Orbitals are incredibly efficient at creating living area per unit mass. IIRC 1% of Mercury's mass could create a full Dyson Swarm around the sun and have billions of times of the living area of Earth; 3. Space orbitals as typified by an O'Neil Cylinder (being 2-4 miles wide and 20-40 miles long) don't require new physics or new materials. Stainless steel has sufficient tensile strength; 4. Orbitals easily allow energy generation from solar power collection, which in space would be much more efficient than on Earth. So this idea isn't even predicated on nuclear fusion power generation becoming commercially viable. If that does happen, this becomes even more likely. The point is it's not required; 5. Dyson Swarms (being a collection of orbitals that would capture the energy output of the Sun in the same way that water droplets in a fog would obscure something) can be built incrementally. We use the term "Dyson Swarm" instead of the original "Dyson Sphere" because of the misconception that a Dyson Sphere is a rigid sphere. There is no known of theorized material with sufficient strength for that. Same for ringworlds; 6. Such a Dyson Swarm built between the orbits of Venus and Mars would not be that crowded. The mean distance between orbitals would still be hundreds of thousands of kilometers; 7. Orbitals will generate heat. That heat needs to be vented. The only way to do that in space is by expelling mass, which isn't really sustainable, or by radiating it away. Physics tells us that the wavelength of light radiated away is basically just a function of temperature of the radiating object. At any reasonable temperature, that means largely infrared ("IR") radiation; 8. The amount of energy such a megastructure would have available is beyond comprehension. We use an estimated 10^11 Watts of power. Capturing Solar output would mean ~10^26 Watts of power. That means if the population of humans was a quadrillion people (ie 10^15), the average power each person has would be the same as the entire Earth currently uses. Think about that; 9. This is likely the most practical way to travel between star systems, as in imparting momentum from light onto a spaceship. People who have looked at this see it as quite practical to get to ~0.86c this way. Beyond this, believe it or not, the aerodynamic drag of interstellar gas slows you down too much; and 10. The timeline from going from this to coloizing the entire galaxy is pessimistically 10 million years (assuming 0.01c and 100k LY across the galaxy). If you accept these premises, such a structure would stick out. There's no hiding something like this. The signature would be heavy on the IR spectrum and would be visible from thousands of LY away. A galaxy that had been fully colonized this way would be obvious from millions of LY away. I find this idea attractive because it is incremental and requires no new physics or theoretical materials (unlike, say, the many attempts to come up with a mathematical basis for warp drives). Radio band usage in this scenario is completely irrelevant.

friend_and_foe 4y ago
You're ignoring the temporal aspect. A dyson swarm would be visible thousands of light years away, thousands of years after it happened. Humans current technological kick start has only been going on for a hundred or so years. Our entire known history, complete with dark ages, is a few thousand years. By the time something even sees it, who knows how much such a civilization will have changed. Would the dyson swarm even be there? Would the civilization? Is it even worth investigating? Now reason the same way for a galaxy and millions of years. Modern humans haven't even existed for one million years. A civilization could be born, evolve and die with such a light in their sky, who's to day they'd even notice something off about such a galaxy in their sky. Its just a little redder, a little older, a little farther away. And then, supposing someone existed at just the right time and place and noticed, what would they do about it?
- DesiLurker 4y ago
  > A civilization could be born, evolve and die I feel this line is doing quite a bit of heavy lifting there because this in itself is a solution to fermi's paradox. if a type-2 civilization could 'just die' then we should probably think about possible way in which they could completely (& i mean completely as in the last humans w/o the ability to bear & raise children) be wiped off. the only way I can imagine that besides an AI is a planetary gray goo scenario. but even that does not works for a type-2 civ. & if an AI wipes us out then there is a good chance that the AI itself will be around to take over the leftovers. The only realistic solution for the paradox IMHO is that intelligence (not life) is really really rare and has happened here on earth with humans by accident. I mean Dinosaurs existed for about 160M years but the did not develop intelligence and we only developed in last couple of million years only. the other rather handwavy solution I can imagine is that all intelligent civilizations ultimately give up meatspace and evolve into some hybrid quantum-foam dwelling semi-temporal beings because that gives them most amount of 'freedom'.
- cletus 4y ago
  You touch on a couple of issues. The first is that civilizations tend to be short-lived. There are only really two ways out of this: they wipe themselves out or they somehow "transcend". "Transcending" is a trope of sci-fi (eg David Brin's Startide Rising series, the Iain M. Banks Culture series) but it's very handwavy. We really have no conception of what that might be. Living in the quantum world? Higher dimensions? This is really the sci-fi version of godhood. As for wiping ourselves out, that's becoming increasingly harder. We are currently in the latter stages of it being possible to wipe out humanity, despite all the talk of Armageddon. If would really take a large cosmic event at this point. I'm talking the Earth being hit by a truly massive object, the kind that puts the dinosaur-killing asteroid to shame. Things like nuclear war, biological wars, disease, etc could be truly devastating but kill every last one of us? Easier said than done. It would really take making the Earth truly uninhabitable. Now another K2 civilization currently has the ability to wipe us out by virtue of the huge amounts of energy they have. Two talked about forms are the Nicoll-Dyson beam (quite literally, turning the energy of a star into something that would bather the target in radiation) and relativistic kill missiles. Barring some major disaster, in 1000 years this is unlikely to be the case, particularly if we reach other stars. Of course there's something we might not be able to conceive of but this too feels very handwavy. The second thing is the Fermi Parai Paradox itself. You can argue that not every civilization goes the Dyson Swarm route or even continues to grow. Some might fade into irrelevance. There are a bunch of possibilities. But we're not concerned with what's likely or expected. Imagine if there were 5 civilizations in the Milky Way. What are the odds that none of them become K2 civilizations and surviving long term? There's some nonzero possibility. But what if there were 1000 civilizations? As N gets higher the probability that zero of them become long-lived K2 civilizations starts approaching zero. We look around us and see... nothing. That doesn't mean there's no one out there but it looks increasingly likely the galaxy isn't teeming with spacefaring life. I, for one, think it's most likely that we are the only spacefaring civilization in the Milky Way, at least within our light cone (which means much the same thing).

by cletus 4y ago

friend_and_foe 4y ago

You're ignoring the temporal aspect. A dyson swarm would be visible thousands of light years away, thousands of years after it happened. Humans current technological kick start has only been going on for a hundred or so years. Our entire known history, complete with dark ages, is a few thousand years. By the time something even sees it, who knows how much such a civilization will have changed. Would the dyson swarm even be there? Would the civilization? Is it even worth investigating? Now reason the same way for a galaxy and millions of years. Modern humans haven't even existed for one million years. A civilization could be born, evolve and die with such a light in their sky, who's to day they'd even notice something off about such a galaxy in their sky. Its just a little redder, a little older, a little farther away. And then, supposing someone existed at just the right time and place and noticed, what would they do about it?

DesiLurker 4y ago
> A civilization could be born, evolve and die I feel this line is doing quite a bit of heavy lifting there because this in itself is a solution to fermi's paradox. if a type-2 civilization could 'just die' then we should probably think about possible way in which they could completely (& i mean completely as in the last humans w/o the ability to bear & raise children) be wiped off. the only way I can imagine that besides an AI is a planetary gray goo scenario. but even that does not works for a type-2 civ. & if an AI wipes us out then there is a good chance that the AI itself will be around to take over the leftovers. The only realistic solution for the paradox IMHO is that intelligence (not life) is really really rare and has happened here on earth with humans by accident. I mean Dinosaurs existed for about 160M years but the did not develop intelligence and we only developed in last couple of million years only. the other rather handwavy solution I can imagine is that all intelligent civilizations ultimately give up meatspace and evolve into some hybrid quantum-foam dwelling semi-temporal beings because that gives them most amount of 'freedom'.
cletus 4y ago
You touch on a couple of issues. The first is that civilizations tend to be short-lived. There are only really two ways out of this: they wipe themselves out or they somehow "transcend". "Transcending" is a trope of sci-fi (eg David Brin's Startide Rising series, the Iain M. Banks Culture series) but it's very handwavy. We really have no conception of what that might be. Living in the quantum world? Higher dimensions? This is really the sci-fi version of godhood. As for wiping ourselves out, that's becoming increasingly harder. We are currently in the latter stages of it being possible to wipe out humanity, despite all the talk of Armageddon. If would really take a large cosmic event at this point. I'm talking the Earth being hit by a truly massive object, the kind that puts the dinosaur-killing asteroid to shame. Things like nuclear war, biological wars, disease, etc could be truly devastating but kill every last one of us? Easier said than done. It would really take making the Earth truly uninhabitable. Now another K2 civilization currently has the ability to wipe us out by virtue of the huge amounts of energy they have. Two talked about forms are the Nicoll-Dyson beam (quite literally, turning the energy of a star into something that would bather the target in radiation) and relativistic kill missiles. Barring some major disaster, in 1000 years this is unlikely to be the case, particularly if we reach other stars. Of course there's something we might not be able to conceive of but this too feels very handwavy. The second thing is the Fermi Parai Paradox itself. You can argue that not every civilization goes the Dyson Swarm route or even continues to grow. Some might fade into irrelevance. There are a bunch of possibilities. But we're not concerned with what's likely or expected. Imagine if there were 5 civilizations in the Milky Way. What are the odds that none of them become K2 civilizations and surviving long term? There's some nonzero possibility. But what if there were 1000 civilizations? As N gets higher the probability that zero of them become long-lived K2 civilizations starts approaching zero. We look around us and see... nothing. That doesn't mean there's no one out there but it looks increasingly likely the galaxy isn't teeming with spacefaring life. I, for one, think it's most likely that we are the only spacefaring civilization in the Milky Way, at least within our light cone (which means much the same thing).