Considering an infinite universe it must contain an infinite amount of energy and matter if it's density is above zero. Given infinite time we can access an infinite amount of it these conditions are true.
OK, you've got me there. Given an infinite amount of time, and a way to get to it, we could collect an infinite amount of energy. Of course, all the stars in our galaxy are eventually going to burn out, and the other galaxies are all accelerating away, so getting there may be the biggest hurdle. But hey, we have infinite time to fly through the deep dark to get there, right? At least, until the stored energy from the last of our suns runs out...
You still are assuming conditions postulated by big bang cosmology. For instance you assume all galaxies are moving away from us,
That is not an assumption. That is an observation. And they're not just moving away, they're
accelerating.
assume all stars will eventually burn out (without new ones to replace them).
Unless new hydrogen is created, once it's all used up, there's no more to make new stars.
Given an infinite universe there could very well be a case where matter is created out of literally nothing....
At which point we'd have another Big Bang, likely erasing this universe.
Still you are not counting in the opportunity cost. You really have to understand that concept before you start arguing economics.
I'm afraid I just ignore it because from what you've been describing I just don't agree with the idea. You tell me I have to understand it but maybe I do and I just think it's wrong.
You reject the notion that one resource cannot be used for two purposes at the same time? I don't think we can continue this conversation if you think that you and I can breathe the same air at the same time.
You also don't quite understand the amount of matter needed to go into a Dyson sphere. It's not a forest.
Yes, a lot of matter is needed indeed. Maybe using the entire mass of Jupiter would not be enough. I don't know. But we weren't discussing the feasibility of a Dyson sphere, we were discussing whether it would make sense to use the energy of the sun to build it if it were possible. I think it does providing you have enough matter and that your machines can self-replicate (yes indeed I insist on that, because it's totally necessary imho).
Of course it would make sense if you could. It wouldn't be cheap, even with self-replicating robots. You're also neglecting the R&D costs that go into the robots, the Dyson sphere, the energy transfer systems, these things don't design themselves.
You're a little fixated on this self-replicating robot thing, so I can understand why you would miss my point here. When you build something, you need supervisors, at minimum, to make sure that the robot fleet doesn't start building attack ships instead of Dyson cloud components. These people can't exactly commute. They're going to set up colonies. And they won't be alone. if the technology is there, there is a significant percentage of the population which will avail themselves of it and set up their own colonies. Any frontier draws humans like flies to shit.
What do you think the birth rate will be out in those colonies?
I genuinely don't know. But again, it seems that the more advanced a society is, the less children it makes. Will humanity keep expanding exponentially for centuries? I don't know. But it's absolutely not certain.
Neither is a plateau at 10 billion, even if humanity stays on Earth.