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2004-Apr-13, 10:56 PM
Ever since seeing that episode on Star Trek: The Next Generation about Dyson Spheres, I've been interested in the concept.

While surfing over on The Planetary Society's website, I came across this interesting article titled "Searching For Dyson Spheres.

http://planetary.org/news/2004/dyson_spheres.html

I've found a couple of threads by searching the boards here but would like a bit more detail on the concept. I mean, the idea is captivating. But, theoretically speaking, how would you overcome events such as cosmic storms, solar flares etc? What's your take on the subject Phil? Bad Astronomy?

Also, what are your opinions on the odds of the existance of these spheres (if life exists elsewhere in the universe?)

TriangleMan
2004-Apr-14, 11:05 AM
First of all I'll assume Dr. Dyson came up with a way to solve the problem that a Dyson Sphere would not have a meaningful atmosphere.

Otherwise I've always found Dyson spheres, while an impressive sci-fi concept (like you said, it's captivating), would be something impractical to build or operate. If we had the capability to build such a thing we'd also have the technology to inhabit other planets instead. Dyson spheres are not going to happen.

As for the rest of the universe I'll settle for finding intelligent life first before speculating on how they live.

Swift
2004-Apr-14, 01:13 PM
I also have always been interested in Dyson spheres and that episode of ST:NG is one of my favorites. A couple of thoughts...

The postulation I've read is that a civilization would probably only do this if they did not develop some way to leave their own solar system (faster-than-light, generation ships, whatever). There are at least two reasons for building one: a huge amount of living space and the ability to collect all of the energy output from a sun. I could also imagine it might have a defense advantage, in that it would at least alter the spectroscopic signature of the enclosed sun (no visible light, just infared) so it might make it harder to be found by "others". It also would be extremely cool; one can hope that at the point you have the technology you might just do it for the sake of doing it.

Not only keeping the atmosphere in, but gravity itself is a problem. One idea is to spin it; that gives you a pseudo-gravity zone around the equator, decreasing to zero-g at the poles. That actually might be an advantage, you could put zero-g/vacuum industries at the poles, as you would put such things in Earth-orbit. You still need something to keep the atmosphere in, the easiest is probably making domed cities. I've also heard the idea of using "gravity generators", but I think if you could control gravity like that, you probably have FTL.

One variant of this idea is Larry Niven's Ringworld. Instead of an entire sphere, you "just" build a ring the size of the Earth's orbit around a sun. You make it a couple of hundred miles wide, build 100 mile walls along the edge, and spin it; you don't need a roof to keep your air in. I highly recommend you read his Ringworld books, both for ideas and because they are great reads.

Iain Lambert
2004-Apr-14, 02:32 PM
Even Niven rings seem rather large and extravagant to me - I'd just go for a Banks Orbital. Flood optional, naturally.

PeterFab
2004-Apr-14, 04:12 PM
Even Niven rings seem rather large and extravagant to me
Fragile little things. No, lets go for an Alderson Disk. A big disk centered around the Earth's orbit, with a thickness about the diameter of Earth.

Niven mentioned it in 'Bigger Than Worlds' this essay is in 'All the Myriad Ways' and 'Playgrounds of the Mind'.

Nowhere Man
2004-Apr-14, 04:15 PM
Both a Niven ring and a solid Dyson sphere are gravitationally unstable -- gravity alone won't keep the star centered in them. There's no way to help this with a sphere, but Niven mounted thrusters on the rim of his ring to compensate.

I think Dyson's original concept was not a solid sphere but a cloud of artificial worldlets, surrounding the star in orbits with all kinds of inclinations.

Fred