6 ms·

I see that. My point is that if the captured energy is used, and thus ultimately dissipated as heat, on the planet's surface, that planet is sooner than later g

I see that. My point is that if the captured energy is used, and thus ultimately dissipated as heat, on the planet's surface, that planet is sooner than later going to have climatic imbalance.

yreg 2y ago
You don't redirect all the energy to the home world. You dissipate the heat into space. Which is why you can't hide, anyone who aims their instruments on your system will detect the heat and see that the star is obstructed.
kiba 2y ago
Earth already do this. We only use some energy for our purpose.
- sdwr 2y ago
  We are using the sun's energy that hits the earth. Some as light (which turns into heat), some as electricity (which turns into heat), and some as plant food > animal food > oil (which turns into heat) A Dyson sphere would capture the sun's energy that leaves the sun, not just the fraction that hits earth. Using that energy on earth would release far more heat than our current activities.
  - kiba 2y ago
    It would indeed be inadvisable to use all of sun energy captured on Earth, but they're not going to be used entirely on Earth.
  - maxerickson 2y ago
    The Earth radiates away solar energy, it's only here for a (figurative) moment. Human activities that convert other energy into heat don't particularly impact this process, the amount of energy from the sun is much larger.
vitiral 2y ago
Planet? Dyson swarms orbit a SUN, not a planet
- fikama 2y ago
  Its not where energy is sourced but wher its used. And assuming it will be civilisation's planet like Earth. The whole energy of the swarm will be used there. - It just has to increase temperature (due to additional energy on the planet)
  - deleted 2y ago
    [deleted]
  - mcmoor 2y ago
    There's Mathrioshka Brain https://en.m.wikipedia.org/wiki/Matrioshka_brain https://en.m.wikipedia.org/wiki/Matrioshka_brain which uses the energy then and there for computation.
    - TheLoafOfBread 2y ago
      That actually makes no sense. You can't use (destroy) energy, you can only run it through processor, which will change it into heat while transistors inside are switching on/off. It is like a water wheel doing work by water flowing through it, but ultimately amount of water before and behind water wheel is same. Thus the question still stands, what happens to heat in such thing? Does it get recycled by some unknown device? Then it is closed system, you don't need input from outside. It won't get recycled? Then such device needs to get hot from dissipating that heat.
      - vitiral 2y ago
        ? I think you are very confused. Yes, there is conservation of energy, but not conservation of entropy. See the second law of thermodynamics
  - vitiral 2y ago
cletus 2y ago
There are several possibilities here. First, the Earth already receives a ton of energy from the Sun that is "wasted". We estimate that at about 10^16 Watts of power, compared to humanity's energy usage, estimated at 10^10-10^11 watts. So Earth has a ton of energy dissipiation "built in" that we're not "using". Second, there is some inefficiency and thus heat dissipation in converting solar output into usable energy. Doing that in space means a bunch of heat dissipation happens in space rather than on your planet. Third, it's relatively straightforwward to counter any increased heat dissipation on your planet by reducing that solar output that hits your planet. How? You build something at the EArth-Sun L1 Lagrange point. Reducing that solar output that hits the EArth by 1% would likely be unnoticeable to us but could cool the Earth significantly. Also, what do you build there? Well, lots of things. More orbitals, solar power collectors, etc. Fourth, how do you get power down to a planet? There are several candidates. One is to beam it down. This adds a conversion cost. But here's another: you build a n orbital ring [1] 100-150km above the EArth's surface. There are a ton of reasons you'd want to do this: interplanetary travel, cheap travel to and from LEO and easier travel across the planet (ie up to the ring, down to another point on Earth on cable cars, basically). But consider this: it gives you a rigid structure to attach solar power collectors to and you can run power transmission cables down from the ring to the planet's surface. [1]: https://www.youtube.com/watch?v=LMbI6sk-62E https://www.youtube.com/watch?v=LMbI6sk-62E
- ericd 2y ago
  I wonder how much reaction mass we’d need every year to keep something stationed at a Lagrange point to block 1% of earth’s light, for combatting global warming. 1% of earth’s light would be a heck of a solar sail. Looks like 1% would be 13.3 watts per meter, cross section of earth yields ~5.4x10^14 watts. Assuming perfect reflective, multiplying by 2/c gives 3.6x10^6 N. So like half of the thrust of one of Saturn V’s engines? So… a lot of reaction mass, or some really powerful ion engines and a ton of power. So maybe not the most practical idea.
  - cletus 2y ago
    It's true that the L1 Lagrange point is unstable so would need some station-keeping. It's an issue but it's a solvable issue. For one thying you have a bunch of energy to spend. For another, the solar wind itself can be used to provide momentum going out if what you have there is sufficiently light. But there's another option: statites [1]. Statites are solar power collectors that have an incredibly thin sail to the point that they don't need to orbit the Sun at all. This means you have a bunch more options for positioning. Clearly the Earth will continue to revolve around the Sun but a sufficient swarm of statites on the EArth's orbital plane could have the same net effect as, say, driving beneath a bunch of stationary umbrellas. Or statites can themselves do station-keeping at L1. They can angle themselves to provide momentum in a bunch of directions. Or they can orbit the L1 point similar to how JWST orbits L2. Their ability to use the solar wind for directional momentum could satisfy station keeping needs. [1]: https://en.wikipedia.org/wiki/Statite https://en.wikipedia.org/wiki/Statite
kobalsky 2y ago
if a civilization needs so much power they build a dyson sphere they probably have terraforming nailed. that kind of technology probably takes hundred of thousands of years of technological development and we have had electricity for how long?
- pests 2y ago
  I think you are overestimating by many orders of magnitude.

I see that. My point is that if the captured energy is used, and thus ultimately dissipated as heat, on the planet's surface, that planet is sooner than later going to have climatic imbalance.

yreg 2y ago

You don't redirect all the energy to the home world. You dissipate the heat into space. Which is why you can't hide, anyone who aims their instruments on your system will detect the heat and see that the star is obstructed.

kiba 2y ago

Earth already do this. We only use some energy for our purpose.

sdwr 2y ago
We are using the sun's energy that hits the earth. Some as light (which turns into heat), some as electricity (which turns into heat), and some as plant food > animal food > oil (which turns into heat) A Dyson sphere would capture the sun's energy that leaves the sun, not just the fraction that hits earth. Using that energy on earth would release far more heat than our current activities.
- kiba 2y ago
  It would indeed be inadvisable to use all of sun energy captured on Earth, but they're not going to be used entirely on Earth.
- maxerickson 2y ago
  The Earth radiates away solar energy, it's only here for a (figurative) moment. Human activities that convert other energy into heat don't particularly impact this process, the amount of energy from the sun is much larger.

vitiral 2y ago

Planet? Dyson swarms orbit a SUN, not a planet

fikama 2y ago
Its not where energy is sourced but wher its used. And assuming it will be civilisation's planet like Earth. The whole energy of the swarm will be used there. - It just has to increase temperature (due to additional energy on the planet)
- deleted 2y ago
  [deleted]
- mcmoor 2y ago
  There's Mathrioshka Brain https://en.m.wikipedia.org/wiki/Matrioshka_brain https://en.m.wikipedia.org/wiki/Matrioshka_brain which uses the energy then and there for computation.
  - TheLoafOfBread 2y ago
    That actually makes no sense. You can't use (destroy) energy, you can only run it through processor, which will change it into heat while transistors inside are switching on/off. It is like a water wheel doing work by water flowing through it, but ultimately amount of water before and behind water wheel is same. Thus the question still stands, what happens to heat in such thing? Does it get recycled by some unknown device? Then it is closed system, you don't need input from outside. It won't get recycled? Then such device needs to get hot from dissipating that heat.
    - vitiral 2y ago
      ? I think you are very confused. Yes, there is conservation of energy, but not conservation of entropy. See the second law of thermodynamics
- vitiral 2y ago

cletus 2y ago

There are several possibilities here. First, the Earth already receives a ton of energy from the Sun that is "wasted". We estimate that at about 10^16 Watts of power, compared to humanity's energy usage, estimated at 10^10-10^11 watts. So Earth has a ton of energy dissipiation "built in" that we're not "using". Second, there is some inefficiency and thus heat dissipation in converting solar output into usable energy. Doing that in space means a bunch of heat dissipation happens in space rather than on your planet. Third, it's relatively straightforwward to counter any increased heat dissipation on your planet by reducing that solar output that hits your planet. How? You build something at the EArth-Sun L1 Lagrange point. Reducing that solar output that hits the EArth by 1% would likely be unnoticeable to us but could cool the Earth significantly. Also, what do you build there? Well, lots of things. More orbitals, solar power collectors, etc. Fourth, how do you get power down to a planet? There are several candidates. One is to beam it down. This adds a conversion cost. But here's another: you build a n orbital ring [1] 100-150km above the EArth's surface. There are a ton of reasons you'd want to do this: interplanetary travel, cheap travel to and from LEO and easier travel across the planet (ie up to the ring, down to another point on Earth on cable cars, basically). But consider this: it gives you a rigid structure to attach solar power collectors to and you can run power transmission cables down from the ring to the planet's surface. [1]: https://www.youtube.com/watch?v=LMbI6sk-62E https://www.youtube.com/watch?v=LMbI6sk-62E

ericd 2y ago
I wonder how much reaction mass we’d need every year to keep something stationed at a Lagrange point to block 1% of earth’s light, for combatting global warming. 1% of earth’s light would be a heck of a solar sail. Looks like 1% would be 13.3 watts per meter, cross section of earth yields ~5.4x10^14 watts. Assuming perfect reflective, multiplying by 2/c gives 3.6x10^6 N. So like half of the thrust of one of Saturn V’s engines? So… a lot of reaction mass, or some really powerful ion engines and a ton of power. So maybe not the most practical idea.
- cletus 2y ago
  It's true that the L1 Lagrange point is unstable so would need some station-keeping. It's an issue but it's a solvable issue. For one thying you have a bunch of energy to spend. For another, the solar wind itself can be used to provide momentum going out if what you have there is sufficiently light. But there's another option: statites [1]. Statites are solar power collectors that have an incredibly thin sail to the point that they don't need to orbit the Sun at all. This means you have a bunch more options for positioning. Clearly the Earth will continue to revolve around the Sun but a sufficient swarm of statites on the EArth's orbital plane could have the same net effect as, say, driving beneath a bunch of stationary umbrellas. Or statites can themselves do station-keeping at L1. They can angle themselves to provide momentum in a bunch of directions. Or they can orbit the L1 point similar to how JWST orbits L2. Their ability to use the solar wind for directional momentum could satisfy station keeping needs. [1]: https://en.wikipedia.org/wiki/Statite https://en.wikipedia.org/wiki/Statite

kobalsky 2y ago

if a civilization needs so much power they build a dyson sphere they probably have terraforming nailed. that kind of technology probably takes hundred of thousands of years of technological development and we have had electricity for how long?

pests 2y ago
I think you are overestimating by many orders of magnitude.