[oceanplexian]

Or civilizations find a better way to generate energy.

Why would you build this big mass around a star when you can create your own, much more efficient fusion reactor where and when you need it? Stars are insanely inefficient; they convert less than 1% of their mass into energy, take billions of years to do it, and you can’t turn them off when you aren’t using them. Plus, if you wanted to use it for some exotic warp drive or something, you would have to haul the mass of a star around. None of it really makes sense to me.

[dividedbyzero]

Or civilizations stop growing and never get to a Dyson something stage. You're a hundred billion or so immortal beings that can engineer their very wants and propensities, with a trillion autonomous robot minions, near-inexhaustible amounts of raw materials from asteroids, and more than enough renewable energy to live very happily ever after, why keep growing? Maybe the great filter is just that, a shift in priorities that prevents the others from getting big enough to be easily detectable.

[jmyeet]

The most likely alternative energy soruce is fusion. Personally I'm not convinced this will ever be commercial. I'm not saying it won't be but there are huge problems to overcome, most notably destroying the container and plasma turbulence.

We already have the tech for space-based solar. Putting it in space makes it much more efficient. It's relatively low tech and doesn't require exotic materials or solving the massive engineering problems that fusion (for example) does.

Then there are other way more exotic methods (eg antimatter, black holes).

But all this misses the point. If you generated 10^26 Watts of power on Earth using fusion power you would still need to dissipate that heat into space or you'd quickly cook the Earth. So you're pretty much back to where you started.

What I like about the Dyson Swarm idea is that it requires no new physics and is relatively low-tech. So even if there is something far-future that's an option (eg antimatter, black holes) you have to ask questions like: Will everyone reach that point? Will civilizations build Dyson Swarms as an intermediate step anyway? How long is that reality? Will there still be a mixed-use future with both space-based solar and exotic enegy generation?

The Sun radiates a ton of energy into space. Capturing it is relatively simple. Dismissing that seems to defy credulity (IMHO).

[voldacar]

Yeah any civilization capable of building a dyson swarm could probably develop technology to dissasemble a star and use its matter for a more efficient nuclear process. I'm not sure how you would practically go about doing that though, a dyson swarm at least is relatively simple (in principle) to construct

[ajkjk]

"Disassembling a star" has to actually be possible in principle for this line of reasoning to make any sense.

[ceejayoz]

Oh, we've plenty of evidence of that going on.

https://arstechnica.com/science/2022/03/study-theres-no-blac...

> "Our best interpretation so far is that we caught this binary system in a moment shortly after one of the stars had sucked the atmosphere off its companion star, said co-author Julia Bodensteiner, an ESO fellow in Germany. "This is a common phenomenon in close binary systems, sometimes referred to as 'stellar vampirism' in the press. While the donor star was stripped of some of its material, the recipient star began to spin more rapidly."

[ajkjk]

Well, that's by another star, not by engineering.

[est31]

There are some sources that discuss the idea here:

https://sites.google.com/view/sources-stellar-engines https://www.youtube.com/watch?v=v3y8AIEX_dU

[voldacar]

the Caplan engine is quite nice! Assuming there is no need to move the solar system, it seems advantageous to dispense with the dyson sphere and just use the mechanism described to siphon out mass from the sun to directly power fusion reactors. Even a perfect dyson sphere captures <1% of the energy released by the sun's nuclear fusion.

[kibwen]

The efficiency of stellar fusion doesn't matter, only the cost does. Whether or not humanity decides to harvest it, the sun emits a ludicrous amount of energy for free, just waiting to be captured with today's tech.

Of course, you'd never want to actually use a Dyson Thing to ever transmit 100% of the Sun's energy to Earth, because all energy turns to heat eventually and you'd scour the planet clean from all the inevitable waste heat.

[chmod775]

> they convert less than 1% of their mass into energy

Isn't that about typical for fusion reactions? What are you fusing in your hypothetical reactor?

[maxerickson]

Get a star to eject mass is probably one of the more reasonable ways to go somewhere else in the galaxy.

You need a pretty big vessel to be self sufficient.

[Hydraulix989]

A star IS a fusion reactor