When I go to a physics conference and utter nonsense phrases in the way that Stephen Hawking does, it doesn't work.
What is "it"? And what does talking about physics have to do with being affected by physics?
When I go to play tennis and wave my limbs in erratic patterns the way Andre Agassi does, it doesn't work. I think physics things can be a little more complex then you imply.
I'm not sure what you're talking about here? Are you trying to say that playing tennis is applying physics or something?
Anyway, if you dedicated as much time to playing tennis as Andre Agassi did, it's not unlikely you'd be similarly good at it. This doesn't have anything to do with your or his understanding of physics, though.
The laws of physics just ensure that the results of waving your tennis racket will be exactly the same as when Andre Agassi does, assuming all of the relevant parameters are identical, i.e. the ball's motion and speed, your motion and speed, the wind's, etc.
"So you want to be a wizard" has colored my view of wizardry. In particular, it's not just nonsense phrases; it's specifying a bunch of properties in a terribly precise language.
I'm not sure if D&D explicitly mentions anywhere what it takes to become a wizard.
I think, it's entirely setting-dependent what is required to become a wizard. At one end of the scale it's something everyone can do and indeed uttering nonsense syllables is all it takes (if that).
Ursula K. LeGuin's Earthsea magic is like that: Speak a thing's truename and you gain power over it. Training is only required because the 'Language of Creation' is tricky to use and pronounce and there's a ton of truenames to learn.
On the other end of the scale it's something you must be born with. E.g. in Mythic Europe, Ars Magica's default setting you're either born with 'The Gift' or not. No amount of studying or training will ever enable you to cast the simplest cantrip if you don't have it.
In D&D 3e and later this is comparable to the difference between wizards and sorcerers. Still, 'Wizardry' is not a skill like 'Athletics'. So you must have levels in a spellcasting class or you cannot do it (well okay, in 4e it only takes a feat...).
That doesn't mean it's not physics; I mean, Michael Jordan can reach things I can't, and I can slam-dunk in ways that he can't. (Seriously, have you have seen MJ try to slam-dunk a 3-ft tall hoop? It's silly how bad he is at it.) The fact that only people with certain innate skills and the right training can handle magic doesn't make it not physics.
You aren't talking about physics. Physics means that if you have the same size and distribution of mass as Michael Jordan (i.e. your muscles are exactly as strong as his) you can jump exactly as high as him.
Of course if you aren't as large as he is, you'll never get to test it out and even if you were, acquiring the same distribution of mass will probably take a couple of years of regular training, but this isn't a question of physics!