[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?"

[MattPalmer1086]

Got it, I missed that part of it. Totally agree that just because you can build a Dyson sphere doesn't imply you're going to travel a lot.