> I'm really fascinated by the idea that physics might be completed in my lifetime.
That's an unfortunate thought to be fascinated by. You should study some physics, instead of reading popular articles about it, or even what pre-eminent physicists say about their work.
I can simply illustrate the situation by saying if a question Q eventually provides answer A, the a new question Q' arises: why A?
You can tell yourself "it doesn't matter" but quite frankly, at the human scale, physics is already a done deal.
Which only further illustrates why your thought is a bit naïve.
I certainly could read more, but I do have a degree in physics and philosophy.
Certainly there will always be questions like: why something rather than nothing?
However, if you have a (relatively) simple set of rules, like the standard model, which work in every context and (in principle) predicts all observable phenomena, it does seem like you've crossed some kind of threshold. An intellectual threshold - as you say it has limited practical implications. It would be a watershed like observing alien bacteria. You're not going to do much with it, but it seems to put you in touch with the cosmic.
There might still be lots of emergent phenomena we don't fully understand, but we could still be confident that the underlying physics is totally understood. An example of this might be the Navier–Stokes equation - we don't fully understand it, but I don't think many people think that a complete understanding of why nature obeys this law will lead to any fundamentally new physics.
It's certainly possible it's just questions all the way down, perhaps smaller and smaller structures will be observable at higher energies, but it's an open question.
Another option is that we're close to bottoming out all of the complexity - and that's the possibility I find fascinating.
I'm not envisioning a time when every possible question has been answered, instead I'm thinking of a time when any questions about fundamental physics will either have been answered or we can be satisfied that no empirical evidence will answer them.
QM may already have hit this knowledge barrier. We know from Bell inequities there are no hidden variables, there is simply no empirical way to predict with certainty the state of a quantum system. We've hit the edge of the knowable.
"Whereof one cannot speak, thereof one must be silent" - as Wittgenstein might have said about the situation.
In defence of throwaway000002, when I talk with physicists about the idea that physics might be completed they mostly don't think it's likely. I don't think they subscribe to the questions all the way down model, instead they think we have a long way to go yet - though I think most researchers don't have clearly formed views on the subject.
"An example of this might be the Navier–Stokes equation - we don't fully understand it"
We don't fully understand the flow of fluids, whether or not the NS equation is a good model for them. That the theory of elementary particles is more "fundamental" than the theory of turbulence is one point of view, not unreasonable. But another way to look at it is: the science of fluid flows has its own fundamentals, that are true whether or not a particular fluid is made of particles.
I guess what I should have realized, and is my mistake, is that the idea of physics being completed is actually a philosophical issue, and given different philosophical bases you can arrive at different conclusions.
Ultimately, however, it's up to physicists to determine when their work is done, and as you say, they don't think it likely ever will be.
For me things like turbulence and critical phenomena are the more interesting questions out there, because they're still very much human-scale, and our only excuse is that we can't compute at the scale required to verify results, the calculations are just too fantastically large.
That's an unfortunate thought to be fascinated by. You should study some physics, instead of reading popular articles about it, or even what pre-eminent physicists say about their work.
I can simply illustrate the situation by saying if a question Q eventually provides answer A, the a new question Q' arises: why A?
You can tell yourself "it doesn't matter" but quite frankly, at the human scale, physics is already a done deal.
Which only further illustrates why your thought is a bit naïve.