[eloff]

You're probably not addressing me specifically, but there is no yelling in my comment.

I do think we have to ground any interesting discussion by what is possible within the limits of science. Otherwise we're just talking fantasy.

For the most part, I do not think we should discuss the limits of engineering, that is what's practical or not, because we're nobody to say what is practical to a type II or type III civilization.

My dad's astronomy professor told the class it's impossible by the laws of physics to create a telescope that can see exoplanets. He went through the equations to show you could never build a telescope mirror to accomplish that. What he didn't think of is we found other ways to create bigger telescopes and we used gravitational lensing to zoom in on a distant star. Nothing in our understanding of physics changed to allow that, merely a change in how we looked at the problem. That's why it's so arrogant. We don't know everything about what is possible or not, and one day we might just see a way around limitations that seem absolute today. Our short history is filled with us doing that again and again.

[jerf]

"You're probably not addressing me specifically, but there is no yelling in my comment."

Yes, my apologies for the implication. I deliberately wanted to pick a more sensible comment to post under.

"For the most part, I do not think we should discuss the limits of engineering, that is what's practical or not, because we're nobody to say what is practical to a type II or type III civilization."

There's two aspects to engineering we can talk about; fundamental limits, and whether we can attain those fundamental limits.

If you look up the concept of computronium, you'll find a discussion of the fundamental limits of data storage in our universe, for instance. Proposing an alien civilization that exceeds those is stepping into fantasy. We can sensibly discuss what just isn't possible.

On the other hand, given that the "fundamental limit" is "the number of bits you can encode on the event horizon of a black hole", it's at least plausible to consider that no possible engineering project could ever create such a storage device. It's hard to talk about the "what is possible" side.

[eloff]

Yes, I agree. We're probably not going to exceed fundamental limits.

However, some number of fundamental limits might turn out not to be fundamental or there might be a way around rather than through them. We can't be 100% sure of what's impossible, but it is stepping into the realm of the extremely unlikely, at least from our current understanding of the universe.