>In an interview with Robert Wright in 2003, Dyson referred to his paper on the search for Dyson spheres as "a little joke" and commented that "you get to be famous only for the things you don't think are serious" [...]
To be fair, he later added this:
>in a later interview with students from The University of Edinburgh in 2018, he referred to the premise of the Dyson sphere as being "correct and uncontroversial".[13] In other interviews, while lamenting the naming of the object, Dyson commented that "the idea was a good one", and referred to his contribution to a paper on disassembling planets as a means of constructing one.
Thanks for pointing out those follow ups. Interesting stuff!
> correct and uncontraversial
From the original quote it is clear he was referring to the idea of aliens being detectable by infrared because they will absorb all of their sun's energy. Later in the same paragraph he says:
> Unfortunately I went on to speculate about possible ways of building a shell, for example by using the mass of Jupiter...
> These remarks about building a shell were only order-of-magnitude estimates, but were misunderstood by journalists and science-fiction writers as describing real objects. The essential idea of an advanced civilization emitting infrared radiation was already published by Olaf Stapledon in his science fiction novel Star Maker in 1937.
So the Dyson Sphere is a rhetorical vehicle to make an order-of-magnitude estimate, not a description of a thing that he thought could physically exist.
Full quote from the video cited before "the idea was a good one":
> science fiction writers got hold of this phrase and imagined it then to be a spherical rigid object. And the aliens would be living on some kind of artificial shell. a rigid structure surrounding a star. which wasn't exactly what I had in mind, but then in any case, that's become then a favorite object of science fiction writers. They call it the Dyson sphere, which was a name I don't altogether approve of, but anyway, I mean that's I'm stuck with it. But the idea was a good one.
Again he explicitly says this "wasn't exactly what I had in mind." This one hedges a bit more and could be interpreted as his saying the idea of a Dyson Sphere is a good one. He may have meant that in the sense of it being a good science fiction idea though, and he subsequently goes on to talk about that.
The Dyson Sphere is good for order-of-magnitude calculations about hypothetical aliens, and also for selling vapourware to the types of people who uncritically think that vapourware is real.
Have you read the paper itself, not just summaries of the idea? It's obvious from the way he wrote it, dripping in sarcasm. Talking about "Malthusian principles" and "Lebensraum", while hand waving away any common sense questions about how the mass of Jupiter would even be smeared into a sphere around the sun, just saying that he can conceive of it and therefore we should spend public money looking for it. He's having a lark.
Also, he literally said it was a joke, and was miffed that he was best know for something he didn't take seriously.
He thought SETI listening to space radio waves was dumb, so made essentially a satirical paper saying we should look for heat instead, because "an advanced civilization would be using these Shells to capture all star energy, so we could only see the heat"
The "dyson sphere" was a made up and entirely unfounded claim, without justification.
What do you think the limiting factor is? I don't see why we can't scale manufacturing of satellites up as far as we want. If we mine out a substantial fraction of the mass of the earth, we can go harvest asteroids or something.
You need to be able to harness enough raw material and energy to build something that can surround the sun. That does not exist in the solar system and we do not yet have the means to travel further out to collect, move, and construct such an incredibly huge structure. It seems like a fantasy.
The inner planets contain enough mass to create a shell of 1 AU radius with mass of 42 kg/m^2. That sounds like a plausible thickness and density for a sandwich of photovoltaics - GPUs - heat sinks.
You don't build a rigid shell of course, you build a swarm of free-floating satellites in a range of orbits.
The energy to build the system comes from the partial assembled system, plus some initial bootstrap energy. It grows exponentially. We seem to have enough today to build small factories in orbit.
The manufacturing scale comes from designing factory factories. They aren't that far in the future. Most factory machinery is made in factories which could be entirely automated, so you just need some robots to install machines into factories.
I was told ca. 2003 or so that because features on computer chips were getting smaller at some rate, and processor speed was getting faster at some other rate, that given exponential this or that I'd have tiny artificial haemo-goblins[1] bombing around my circulatory system that would make me swim like a fish under the sea for hours on end. But it turned out to be utter bullshit. Just like this.
Great. Now run the numbers to find the energy required to disassemble the planets and accelerating the pieces to their desired locations. For reference, it takes over 10 times of propellant and oxidant mass to put something in LEO.
The burned propellant and oxygen mass (as H2O and CO2) almost all ends up back in the atmosphere when you launch to LEO, so you can keep running electrolysis (powered by solar) to convert it back to fuel.
Sure, but if we're talking about solar engineering, that mass is going to be dispersed in orbit around the sun. You're not going to be reaccumulating that any time soon.
Also it's gravitationally unstable, like Dyson Rings, where as soon as you have any perturbance from the center means that the closer side is more attracted to the sun so it enters a feedback loop.
There are only so many people who can make satellites; there are only so many things to make satellites out of; and there are only so many orbits to put them in. There are only so many reasons why a person might want a satellite. There are only so many ways of placing satellites in orbit and each requires some amount of energy, and we have access to a finite amount of energy over time.
Finally, if we limited ourselves to earth-based raw materials, we would eventually reach a point where the remaining mass of the earth would have less gravitational effect on the satellite fleet than the fleet itself, which would have deleterious effects on the satellite fleet.
Seven reasons are intuitive; I’m sure there are many others.
People can build a factory that makes satellites. And then a factory that makes factories to make satellites.
There is plenty of material in the solar system (see my other response), and plenty of orbits, and launch capability can scale with energy harvested so the launch rate can grow exponentially.
Lots of people will probably decide they don't want any more satellites. But it only takes a few highly determined people to get it done anyway.
> Finally, if we limited ourselves to earth-based raw materials, we would eventually reach a point where the remaining mass of the earth would have less gravitational effect on the satellite fleet than the fleet itself, which would have deleterious effects on the satellite fleet.
The Earth's crust has an average thickness of about 15-20 km.
Practically we can only get at maybe the top 1-2 km, as drill bits start to fail the deeper you go.
The Earth's radius is 6,371 km.
So even if we could somehow dug up entire crust we can get to and flung it into orbit, that would barely be noticeable to anything in orbit.
> What do you think the limiting factor is? I don't see why we can't scale manufacturing of satellites up as far as we want.
A reason. I'm sure that theoretically it's possible, assuming infinite money and an interest to do so. But literally, why would we? There's no practical ways to get the power back on earth, it's cheaper to build a solar field, etc.
And I don't believe datacenters in space are viable, cost wise. Not until we can no longer fit them on earth, AND demand is still increasing.
After a few decades, you need to start replacing all the solar panels.
And the robot army being used to do the construction and resource extraction will likely have a much shorter lifespan. So needs to be self-replicating/repairing/recycling.
Yeah, but besides not having the physical amount of material available in the solar system, or the availability of any technology to transfer power generated to a destination where it can serve a meaningful purpose in the foreseeable future, or having the political climate or capital necessary for even initiating such an effort, or not being able to do so without severely kneecapping the habitability of our planet, there are aren't really any meaningful barriers that I can see.
