> And yes, you absolutely can hack Newton's 2nd law if it's empirically supported. It's frankly bizarre that you keep insisting that you can't do this.
You think it's bizarre that you can't arbitrarily change one prediction in a large, densely interconnected theory? Newton's 2nd law is a consequence of a much larger theory. In order to change it, you have to change the theory that gives rise to it. That will have huge numbers of consequences, but just for Newton's 2nd law, but for pretty much everything else predicted by the theory.
> We already know relativity is technically incorrect because of its singularities.
No, we don't know this. All modern theories are relativistic. We know that General relativity (a.k.a. gravity) has to have some sort of more fundamental quantum analog, but that quantum theory will also be relativistic.
> Don't be ridiculous, GR absolutely does not have an impact on "everything in physics".
You don't need GR to get Newton's 2nd law. You only need Special Relativity. You can't "hack" Special Relativity without doing incredible damage all across physics.
> I said GR was only well tested within the solar system
Wrong. The propagation speed of gravitational waves, the inspiral of binary pulsars, strong gravitational lensing (including around directly imaged black holes), the strong equivalence principle as tested by a triple system with a pulsar, and many other tests.
