My guess is that if you can build Dyson spheres you can build fusion reactors.
> This far the most efficient fusion reactor humanity has available to it exists approximately 1 AU away
Efficient in terms of what? With what are you comparing it to?
The part we don't know how to do yet is getting the material. Building structures that large in space, the resources for it have to come from space, we cannot lift it off Earth. So we need to figure out how to mine asteroids, and maybe also how to mine Mercury. Either one would be sufficient at the start. Neither of those are a well-understood problem, let alone solved, so that's where you should invest resources if you're a billionaire looking to start a Dyson sphere and think SpaceX is on track for launch cost reduction.
I think in terms of science and engineering difficulty, it's a pretty even race as to which is more difficult between making fusion actually produce net useful energy and being able to mine & refine materials from an asteroid + build a sustainable life support system.
The reason fusion "seems easier" is because it is economically far more achievable, and there's a lot more political will behind it so it feels more possible.
Dont know what cheap means for them, but it will never be for free because abundance happens when the supply exceeds demand and I dont see the scenario where the demand for energy is declining in a long run.
If you have the time and raw resources, it was possible with 1960s technology.
[1] https://en.wikipedia.org/wiki/List_of_artificial_objects_in_... .
Would millions or billions of them be better? Yes.
Your description of it as a megastructure might explain some of the confusion: it wouldn't be a structure, but rather a formation of satellites not physically connected to each other.
How do you build a swarm of satellites? Well, first you make 1 satellite, then you make another... :)
My description is Freeman Dyson's description. Naturally you are allowed to come up with ImPostingOnHN's Swarm, which includes a case of zero satellites and no effect on the star emission whatsoever.
> How do you build a swarm of satellites? Well, first you make 1 satellite, then you make another... :)
Sure and the end state of completing Dyson Swarm in Solar system is not achievable with the technology we have. Now let's move on to discuss if one man with a rifle but no vehicle constitutes a Motor Rifles brigade.
Sure, for one possible end state.
The point is that we have the technology to start, because we've already started. Thus, it is achievable given enough time and effort with our current level of technological advancement.
Unless we have some magical solution which can convert waste heat into electricity and thus making such satellite working with 100% effectivity, then such satellite needs to transmit energy with very limited power otherwise it will fry itself up.
Additionally high power laser has currently something around 80% of efficiency. So if you have 10kW of input from solar array on one side, then you are transmitting 8kW via laser and 2kW into satellite itself as a heat. And again, we are in vacuum of space, so good luck with radiating 2kW of power into vacuum.
The fact, that you can't get rid of waste heat would need whole satellite to work close to 100% effectivity, which we don't have technology today