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I love futurist content. Isaac Arthur's channel on Youtube is a fantastic resource for this. I'm convinced that a Dyson Swarm (ie orbitals around a star to near

by cletus 4y ago

I love futurist content. Isaac Arthur's channel on Youtube is a fantastic resource for this. I'm convinced that a Dyson Swarm (ie orbitals around a star to near-fully capture the energy output of the Sun) is our inevitable future because it doesn't require any new physics or exotic tech. Specifically, solar power and stainless steel get you most of the way there. It just makes too much sense. This has all sorts of implications but an important one is how do you travel between stars. The rocket equation is bad news for interstellar travel. Getting to any significant percent of light speed (and decelerating at the other end) requires an insanely massive amount of energy that we really don't have any likely feasible method without exotic things like antimatter or black hole propulsion (yes, this is a thing). Even on vast timescales, you almost need viable nuclear fusion, which is far from a certainty. But these all assume you carry your fuel, which is the real tyranny of the rocket equation. Photos of course have momentum. Enough of them can be used as a form of propulsion, which is what the Starlight project is about. So one proposal for interstellar travel is so-called interstellar highways where energy from a star is concentrated to provide propulsion. You then only have to carry fuel to deceleate. Alternatively you can pre-build infrastructure to use the same technique to slow you down at the other end. Personally, i think this is likely the only viable method we've thus far conceived. I encourage you go watch this [1] if this interests you. [1]:https://www.youtube.com/watch?v=oDR4AHYRmlk https://www.youtube.com/watch?v=oDR4AHYRmlk

JohnJamesRambo 4y ago
Re: Dyson Swarm not needing new tech 1. How do you keep the swarm from hitting each other and staying in the same place and not crashing into the sun as you capture the near-full output of the star? 2. How do you get the power transmitted to our planet?
- ncmncm 4y ago
  The planet does not need the power; it gets all it needs. It is used in space. They don't crash into each other for the same reason our satellites (mostly) don't: they are in selected orbits. But if we have not worked out aneutronic fusion by the time we would be able to build something like this, you might as well write off humanity. By then all the action will be out in the Kuiper Belt, where the truly valuable resource is: cold.
  - vinaypai 4y ago
    > They don't crash into each other for the same reason our satellites (mostly) don't: they are in selected orbits. Real world orbits != Kerbal space program orbits Things don't stay put in an orbit because the (a) earth isn't a perfect uniform sphere (b) gravitational influences from the rest of the solar system will perturb things. Satellites needs regular stationkeeping to keep them in specific orbits. And that is even though low earth orbit is mostly empty. There are only about 27,000 "objects larger than a softball" according to NASA's orbital debris and spacecraft tracking. To build a Dyson swarm you'd need to scale that up trillions of times to capture a significant portion of the Sun's output.
    - cletus 4y ago
      The worst case is orbitals will require some active stationkeeping. If your civilization goes the route of interstellar highways well you already have the ability to focus a large amount of power on a sail of some sort to give propulsion. You could use exactly the same thing to correct orbits. It's also worth noting that orbitals around the Sun are a whole lot bigger volume than orbits around the Earth. LEO orbits have a radius of 6500-7000km. The Earth is 150,000,000km from the Sun so the radius of that is about 8 orders of magnitude more. If you assume orbits between Venus and Mars and include orbits off the Solar plane, the math for a full Dyson swarm the math (IIRC) works out to a mean distance between orbitals of around 100,000km, even with trillions of them.
      - ncmncm 4y ago
        Probably all the orbits are well off the ecliptic, and they turn off their lasers when near it, to keep travel within the ecliptic safe. Stray light from all those x-ray lasers blasting in all directions 24/7 ought to make anything like this easy to spot.
    - skykooler 4y ago
      Satellites in a Dyson swarm can use the Sun's light for stationkeeping, acting as a solar sail. It doesn't work that well at Earth's distance to the sun but the swarm would be much closer to maximise power production per satellite.
- sbierwagen 4y ago
  The outer layers will be heavily shadowed by the inner layers, of course. The builder will keep manufacturing nodes until it hits some equilibrium point between node manufacturing cost and how much power it captures over its lifetime. If nodes are cheap and lifetimes are centuries long you could be fine with outer nodes that only get 0.1% as much sunlight as the innermost nodes.
- Ancalagon 4y ago
  1. ion engines and solar panels and plutonium 2. microwaves I think a bigger issue would be gathering the material and fuel to even consider this a probable future.
- sliken 4y ago
  1. Each one tracks it's nearest neighbors, which should have approximately zero differential velocity. A few gyroscopes or actuators to change the mirrors angles should give you plenty of thrust for controlling orbits. Inevitably probes will drift outward without counter thrust, after all they are basically solar sails. You could also use lasers, microwaves, or similar to cooperatively fly together without colliding. Of course you don't have to be perfect, just good enough that more expensive solutions aren't worth it. 2. Why bother? Make fuel, like antimatter for instance. Then launch them to where you need them. Maybe by a relay system and you could use the kinetic energy to help keep your ideal orbit. Keep in mind these don't have to last forever. Maybe have 3 different designs for how close you are to the sun. Then you get installed in the inner most orbit of that band, then during your useful life you edge towards the outside edge of the band, launching anti matter payloads periodically and then get recycled at the outer edge. As long as you collect significantly more energy than your production cost it's a big win.

by cletus 4y ago

JohnJamesRambo 4y ago

Re: Dyson Swarm not needing new tech 1. How do you keep the swarm from hitting each other and staying in the same place and not crashing into the sun as you capture the near-full output of the star? 2. How do you get the power transmitted to our planet?

ncmncm 4y ago
The planet does not need the power; it gets all it needs. It is used in space. They don't crash into each other for the same reason our satellites (mostly) don't: they are in selected orbits. But if we have not worked out aneutronic fusion by the time we would be able to build something like this, you might as well write off humanity. By then all the action will be out in the Kuiper Belt, where the truly valuable resource is: cold.
- vinaypai 4y ago
  > They don't crash into each other for the same reason our satellites (mostly) don't: they are in selected orbits. Real world orbits != Kerbal space program orbits Things don't stay put in an orbit because the (a) earth isn't a perfect uniform sphere (b) gravitational influences from the rest of the solar system will perturb things. Satellites needs regular stationkeeping to keep them in specific orbits. And that is even though low earth orbit is mostly empty. There are only about 27,000 "objects larger than a softball" according to NASA's orbital debris and spacecraft tracking. To build a Dyson swarm you'd need to scale that up trillions of times to capture a significant portion of the Sun's output.
  - cletus 4y ago
    The worst case is orbitals will require some active stationkeeping. If your civilization goes the route of interstellar highways well you already have the ability to focus a large amount of power on a sail of some sort to give propulsion. You could use exactly the same thing to correct orbits. It's also worth noting that orbitals around the Sun are a whole lot bigger volume than orbits around the Earth. LEO orbits have a radius of 6500-7000km. The Earth is 150,000,000km from the Sun so the radius of that is about 8 orders of magnitude more. If you assume orbits between Venus and Mars and include orbits off the Solar plane, the math for a full Dyson swarm the math (IIRC) works out to a mean distance between orbitals of around 100,000km, even with trillions of them.
    - ncmncm 4y ago
      Probably all the orbits are well off the ecliptic, and they turn off their lasers when near it, to keep travel within the ecliptic safe. Stray light from all those x-ray lasers blasting in all directions 24/7 ought to make anything like this easy to spot.
  - skykooler 4y ago
    Satellites in a Dyson swarm can use the Sun's light for stationkeeping, acting as a solar sail. It doesn't work that well at Earth's distance to the sun but the swarm would be much closer to maximise power production per satellite.
sbierwagen 4y ago
The outer layers will be heavily shadowed by the inner layers, of course. The builder will keep manufacturing nodes until it hits some equilibrium point between node manufacturing cost and how much power it captures over its lifetime. If nodes are cheap and lifetimes are centuries long you could be fine with outer nodes that only get 0.1% as much sunlight as the innermost nodes.
Ancalagon 4y ago
1. ion engines and solar panels and plutonium 2. microwaves I think a bigger issue would be gathering the material and fuel to even consider this a probable future.
sliken 4y ago
1. Each one tracks it's nearest neighbors, which should have approximately zero differential velocity. A few gyroscopes or actuators to change the mirrors angles should give you plenty of thrust for controlling orbits. Inevitably probes will drift outward without counter thrust, after all they are basically solar sails. You could also use lasers, microwaves, or similar to cooperatively fly together without colliding. Of course you don't have to be perfect, just good enough that more expensive solutions aren't worth it. 2. Why bother? Make fuel, like antimatter for instance. Then launch them to where you need them. Maybe by a relay system and you could use the kinetic energy to help keep your ideal orbit. Keep in mind these don't have to last forever. Maybe have 3 different designs for how close you are to the sun. Then you get installed in the inner most orbit of that band, then during your useful life you edge towards the outside edge of the band, launching anti matter payloads periodically and then get recycled at the outer edge. As long as you collect significantly more energy than your production cost it's a big win.