Now this is thinking big... but not clearly.

[unixronin]

(Read the comic here)

There's just one problem with this idea:  If you take a star apart, it stops working.  Then all you have is a whole lot of hydrogen, helium, and relatively limited amounts of heavier fusion products.  The hydrogen you can get far more cheaply and easily, and in more than adequate quantities, from a gas-giant planet; the heavier elements you can mine far more cheaply and easily from asteroids.  It's a pretty poor return for an engineering product of such magnitude -- and for what, really?

If you have the technological capability to take apart a star, you probably have the capability to build a Dyson sphere (or, for that matter, a buuthandi, which is conceptually similar but built on a slightly different principle known as the Dyson bubble), which enables you to actually capture and use all of that energy.  OK, so maybe the star only remains usable (and the sphere only remains habitable) for another five billion years or so ...  You know what?  Honestly, the time to start worrying about that is probably at least about 4.9 billion years from now (which still leaves you about a hundred million years to do something about it).  If, that is, you're still around in 4.9 billion years and still dependent upon individual stars at all.  Odds are, one or the other of those will turn out not to be the case.

Comments

[juuro.livejournal.com]

I think I would prefer a Dyson swarm. With a Dyson sphere (or bubble), I'd be missing the starry sky.

[unixronin.livejournal.com]

You know that one of the design approaches to a Dyson sphere is to put the atmosphere and the habitats on the outside, right...? It neatly solves one of the major drawbacks of a Dyson sphere, that of "no net gravitational field inside a hollow sphere".

[juuro.livejournal.com]

I need to redo the math. It's been rather long since I looked into this. But what is the net gravitational field at 1 AU from Sol? Off-hand it seems to me that we're talking about a microgravity environment. Or less, if there's any angular momentum to the shell.

[unixronin.livejournal.com]

That's a good question, to which I don't remember the answer. Sol's gravity is around 26G at the top of the photosphere, and that's about all I remember on the subject.

[ttocs.livejournal.com]

If I'm doing the math right you'd want the sphere to be at ~3.7e9m from the sun, as opposd to 1AU (149.6e9m) to get 1g on its surface. About 40 times closer in.

[olafthunderfoot.livejournal.com]

gimme a ringworld anyday!

[unixronin.livejournal.com]

The problem with a ringworld is it's unstable in the orbital plane. If it once shifts even slightly out of position, it will continue to shift further and further out of position until it impacts its star.

On a smaller scale, an Orbital -- or a Halo, as Bungie called it -- doesn't have that problem.

[olafthunderfoot.livejournal.com]

didn't the one Niven wrote about have thrusters to correct for shift as well as ramjets to spin it?

[unixronin.livejournal.com]

Well, ramjets wouldn't actually work.

It did have Bussard ramjets for orbital stabilization .... except that the residents had absconded with 95% of them. (And for the record, Bussard ramjets don't actually work either. It's a cool idea, but the physics just won't make it work.)

[olafthunderfoot.livejournal.com]

true, but you'd think that any species that could build a ringworld would make a way to keep it in orbit and it's shadow blocks lined up!

[unixronin.livejournal.com]

It's not Niven's fault that the Bussard ramjet, however cool an idea it sounds at first, turns out not to be workable. :)

[olafthunderfoot.livejournal.com]

good point, but my point was if a species could build a ringworld, they would also have the technology to make it stable.

one of my fave Niven stories wasa short story called "inconstant moon" it's the first thing by him i ever read.

[unixronin.livejournal.com]

Well, they did. They used Bussard ramjets as attitude jets. :) There's no way to change the orbital dynamics of a ringworld to just "make it stable". You have to have some kind of station-keeping thrusters.

[olafthunderfoot.livejournal.com]

agreed!

[james-nicoll.livejournal.com]

If you remove the by-products of fusion, you can extend the life of a star considerably.

[unixronin.livejournal.com]

Sure, no argument. I guess the question is, if you have the technology to remove fusion products and keep a star on the main sequence, what other assumptions are changed by the possession of that level of technology, and do you still need to do so?