The original claim was essentially that energy use can't increase past a certain point because it would result in too much energy density. The obvious flaw in the claim is that it assumes no ability to increase the volume of space in which the energy use takes place, which is an invalid premise. Space is really big.

No, dude, even if you postulate FTL spaceships, the size of the Universe doesn't matter, you always eventually become an explosion. All exponential growth curves are S-shaped.

At this point I'm just repeating basic physics and math at you. I think we both have better things to do with our time. Have a good day.

Yeah, Ehrlich will be right any day now. Just you watch . . .

We don't even know for sure that the universe is finite. You're going to run out of hydrogen before you run out of somewhere to put the heat.