system
Given the following post, respond as if you're commenting on Reddit:
human
[Doctor Who] Exactly how smart is the Doctor? What's the most impressive thing he's built or could build with enough time?
gpt
Smart enough.

Compare him to Superman. Superman is "strong enough" to do whatever he needs to do. That could be bending steel, or it could be moving a planet. Superman's power is that he's strong enough.

The Doctor's power is intelligence, and he's smart enough to do whatever he needs to do. There is essentially no science he isn't a master of, and he tends to know enough about whatever civilization he's dropping into - regardless of the time - to navigate confidently.

His single most impressive invention is probably the sonic screwdriver, which is basically a pocket-sized deus ex machina. It can do damn near anything, from hacking into a computer to reconstructing barbed wire.

But if you give him time, he can build essentially anything. The Time Lords rewrote the laws of physics to make the universe behave the way they wanted it to, and he is the last heir of that knowledge. If you gave him the time and the motivation, he could very likely change the fundamental constants of the universe.

There are things preventing him from doing this, of course. One, he likes the universe much the way it is. He likes the people bouncing around it, and making gravity a bit stronger would make them go away.

And then there's his arrogance. He has been the smartest person in whatever room he's walked into for several thousand years, and he believes, deep down in his heart, that he will always prevail. That makes him a bit too bold, sometimes, and as a result he doesn't always prepare as well as he could.