Comment by antonvs

By not ever be possible, I mean in a practical sense, including e.g. the economics of it, as well as reliability, checkability, etc.

Jassby's article about fusion (https://thebulletin.org/2017/04/fusion-reactors-not-what-the...) describes several well-understood issues that could prevent commercial fusion power from ever being practically possible.

For quantum computers, the situation is quite similar. Michel Dyakonov and several others have laid out the situation well.

At least we don't have anyone claiming that interstellar travel is just 10 years away, yet. Probably because it's more difficult to make an economic case for it. But the issues are quite similar. In principle, in terms of physics, nothing prevents an interstellar journey. In practice, it just isn't going to happen.