[bryanrasmussen]

Being able to build Dyson spheres does not make them capable of going faster than the speed of light, so any civilization capable of building a Dyson sphere would probably still be clustered around a couple stars and that's it.

Would such a civilization spread to more than one star is actually also a question, or would they control their population rationally stay on their Dyson sphere and only start to move when the star had less than 100,000 years left to go.

Only some Dyson sphere variants, like Shkadov thrusters, are primarily conceived as ways to move around. Which personally seems to me less likely, is a civilization, as well as the ability to construct these objects, also going to have a species level interest in going exploring?

[perihelions]

> "Being able to build Dyson spheres does not make them capable of going faster than the speed of light, so any civilization capable of building a Dyson sphere would probably still be clustered around a couple stars and that's it."

Check your math: this galaxy is ~10^5 light-years in size and ~10^10 years in age.

[bryanrasmussen]

what does that have to do with anything I said? Yes, I guess they would be everywhere if their civilization was able to make Dyson spheres 1 year after the creation of the galaxy, also if they decided to

1. Not control their population for some reason.

2. Had some sort of interest in exploring.

3. Implicit also in the speed of light thing, would find it really interesting to send a portion of their population to the next available and suitable star which might be enough light years away to make communication impractical. I mean for our civilization there is some level of argument that says it would be a ridiculous idea to move to a new solar system and we have an intellectual exploratory streak in our species.

I mean we are currently not at the level of being able to do a Dyson sphere, it took us 4.543 billion years (age of earth) to get to the part that somebody could conceive of it. There is also some discussion as to whether or not our civilization is going to last, so given that and the other things I said it seems unlikely to me that any Dyson sphere civilization would actually build more than one, but maybe some build two because binary stars or some other weird circumstance which makes it worthwhile to do.

on edit: if we get to Dyson sphere building capabilities which seems really unlikely, will we build more than one? How many more?

[MattPalmer1086]

The point is that you don't need to go faster than the speed of light. There's more than enough time to cover the entire galaxy in a relatively short period of time at sublight speeds. A few million years is sufficient.

[bryanrasmussen]

yeah, sure, enough time to GO everywhere but not enough time to BE everywhere, which is a different thing entirely, even if all the other things I brought up as to why the aliens weren't everywhere were not things to take into consideration.

So again, still haven't heard any argument why an alien civilization achieving the ability to build Dyson spheres, even if they did so far enough in the past that they would then have adequate time to traverse the galaxy afterwards, would then have to be everywhere?

[MattPalmer1086]

I'm not sure I understand your argument. There is sufficient time, with waves of colonisation to spread across the galaxy many times over. This can include pauses of thousands of years between colonisation waves. Some of those colonies could also build Dyson spheres. You would end up with them scattered all over the galaxy. Even if the colonies dies out subsequently, the spheres would still be detectable.

[bryanrasmussen]

>I'm not sure I understand your argument. There is sufficient time, with waves of colonisation to spread across the galaxy many times over.

yes, there is, if the achievement of Dyson sphere building happened long enough in the past for there to have been sufficient time. 50,000 years ago even, no. The length of human civilization is 6000 years approximately, what if this civilization much, much older than ours 6000 years ago just started building it's first Dyson sphere. For some reason the assumption is that it was far enough in the past that they COULD be everywhere if they wanted to.

But then the phrasing is not that they could be everywhere but rather they would be everywhere, hence no civilization has built Dyson spheres. A lot of this theory that the aliens will go about building lots and lots of Dyson spheres seems based on the assumption that they will be a lot like us, but actually I don't even think we would ever build more than one. If we built a Dyson sphere it would be because we were at the point we needed the energy and we had the technology to do it of course, and we had a political system that could harness everyone to do it. But once we had the Dyson sphere I am not sure we would ever be at the position were we would need another one. Since people tend to have fewer kids the higher their standard of living it may be that with the standard of living of Dyson sphere civ that our population would be at replacement level, that is to say we would never need to move from one Dyson sphere until the sun was just about used up.

So again, sure there is sufficient time with waves of colonization (started far enough in the past) - but waves of colonization assumes a species that has a colonization urge and perhaps one that has a colonization urge greater than that of humanity. That's a pretty big if, considering all the other big ifs in the whole building a Dyson sphere scenario.

[MattPalmer1086]

I'm not sure anyone is arguing that aliens who can build Dyson spheres HAVE to be everywhere. They could, as you say, just build one or two and live there. Or a species that colonises could build them as it goes.

[bryanrasmussen]

That was in fact the statement of the post that I replied to "If they can build Dyson spheres, wouldn't they already be all over the place?"

[caf]

They may not be moving around to explore so much as to keep their solar system safe.

Galactic orbits are far more chaotic than the sedate stable orbits within the solar system - stars closely approach each other on a somewhat regular basis.

[bryanrasmussen]

that's a good point, but I guess at Dyson sphere level a star approaching is like discovering oil on your property.