On 7/8/2021 at 11:11 PM, Pascal_LSGC said:

See also "Dyson shell", lower in the page.

So, the "Dyson swarm" is his proposal. It's quite different from a rigid structure. It's just what Elon Musk and others are doing right now. 🙂
It gets really complicated when you want to cover a significant surface.

I didn't know the "Dyson bubble" with static "satellites" maintained by solar wind pressure. Apparently, it has also some problems.

 

Was it Larry Niven that came up with the Ringworld idea? Or did that originate from a scientific source. Think it was just Niven. I'm wondering about the viability of the Ringworld concept. I think you would still need some form of propulsion to maintain the ring in the proper orientation. 

7 minutes ago, martin-w said:

 

Was it Larry Niven that came up with the Ringworld idea? Or did that originate from a scientific source. Think it was just Niven. I'm wondering about the viability of the Ringworld concept. I think you would still need some form of propulsion to maintain the ring in the proper orientation. 

I haven't read it, but the Wikipedia article mentions that the idea was first described in science fiction.
I would see a solid ring as more feasible that a solid sphere. At least, if it's not to wide, every point of the ring follows a coherent orbital path. It would still need some adjustments to maintain it's orbit.
A solid sphere has a big problem: except from the points at the equator, each point follows a path which is not an orbit coplanar with the star's centre of mass. The worst is at the poles, where the structure has an orbital speed of 0. You can't think of a sphere of this size as a rigid object, it's totally fluid. So, under the dubious assumption that you could even build it, you'd see the sphere collapse toward the sun, flattening from the poles and becoming more and more ellipsoidal until the poles crash into the sun and the other parts dissociate and follow their own orbit.

 

Am interesting video on new techniques to detect life in general:

 

On 7/8/2021 at 4:11 PM, Pascal_LSGC said:

So, the "Dyson swarm" is his proposal.

Seems easy to build to me.

 

2 hours ago, goates said:

Seems easy to build to me.

 

As much as I like Kurzgesagt, he leaves some important problems aside. From some studies, a Dyson swarm would only be able to capture 1% of the sun's energy. That's still a lot, of course, but far from the original hypothesis of a rigid shell.

Why is it so?

All orbits around a mass are necessarily in planes that contain the centre of mass. First, you launch a lot of satellites on the same orbit. When this orbit is populated, you must design another one. But the orbital planes can't be parallel. Both orbits intersect at two opposite point if the altitude is the same. The only way is to change the altitude/shape of the orbit so that the satellites do not collide. Each time you add a new orbital plane, you must take into account all the existing orbits. It becomes really complex really fast.

The fact that all orbital planes intersect each other also implies that the more orbits you add, the more satellites overshadow each others.

It's not impossible, just limited by the pool of altitudes you can play with. And this concept is not practical for habitability because it's not easy to go from one orbital plane to another to meet your neighbours, at least not as easy as crossing a street. 🙂