[Thatcherite]

Contrast the range of applicability of Newton's inverse square law of gravity with Einstein's general relativistic theory of gravity. You can send a rocket around the moon and back using Newton's law and not be off by much; but if you want to understand what happens around a neutron star or a black hole, say, Einstein's theory is essential.

I agree with your general point absolutely. But I was very interested to discover (from Radio Astronomer the Freeper) that Newton is *not* enough for piloting rockets to Mars. He does this for a living. Use Newton and he'll miss his orbit. You've got to use Einsteinian mechanics to travel that distance.

Also GPS devices operate according to Einsteinian physics, or your location would be off by a few metres.

[snarks_when_bored]

Good points. I knew that the GPS system used General Relativity, but, if you'd asked me, I probably would've said that Newton might be able to get you to Mars and back (with more error than a moon trip, of course). I'll trust RadioAstronomer on that.

One of the great successes of General Relativity was its accounting for the precession of the perihelion of the orbit of Mercury, a phenomenon that Newton's theory couldn't account for: