I certainly didn't mean to imply there are reasons it's impossible, it's just a meaningless. My point was that first you would have to define what computronium

I certainly didn't mean to imply there are reasons it's impossible, it's just a meaningless. My point was that first you would have to define what computronium actually is before you can comment on what physical laws apply. It might also be useful to wait until we understand the physical laws that would apply at that scale, which we don't. There are no physical laws that make rocket packs or flying cities impossible either, we just discovered that some aspects are either impractical or we just found a better solution to the same problems. I don't want to sound like I think these kinds of thought experiments are in any way bad, I love them. The best case scenario is that our thought experiments now are like davinci's helicopters. Ridiculous because of our ignorance of the natural world but still extraordinarily clever and farsighted. A more likely case is that they are downright stupid because of that same ignorance. The opinion that an idea we've had or could understand is anything like what construction projects with timescales of millions of years will look like is the silliest kind of hubris. Especially when you start arguing over physical laws of imaginary vaguely defined substances.