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Title: Newtonian Physics (Classical) vs. Quantum Mechanics? Post by: darwinian1 on Jul 28, 2012 Well, because of the rise of quantum physics in the 20th - 21st centuries does that mean most principles in classical physics are officially invalid? Not everything, but I mean loosely electromagnetic radiation and energy, which have obviously been described effectively and correctly with quantum mechanics?
I ask this because quantum mechanics is one of the most interesting topics in physics, besides electricity, magnetism, and thermodynamics. Good answers, thank you Title: Newtonian Physics (Classical) vs. Quantum Mechanics? Post by: das1130 on Jul 28, 2012 Absolutely not.
The only big deal is that since QM became accepted was the great and grand effort to unify the two factions of theories. Title: Newtonian Physics (Classical) vs. Quantum Mechanics? Post by: dartz1221 on Jul 28, 2012 Not in the slightest. It just means we have looked further than before.
For example, when Newton formulated gravity, his theory exactly matched observation - physics hasn't changed, so this is still the case. The difference is that Newton could never conceive of things near the speed of light; primarily because light wasn't assumed to have a speed back then. So Einstein came along and updated it - not changed it, added to it. So now we know what happens at speeds of light and near very large gravitational sources. But here on earth's surface at more humble velocities, we still use Newton's principles because relativity does not apply here. Neither is wrong; they are just used in different circumstances to each other. The situation is the same for quantum mechanics. early on, the Rutherford and Bohr models of the atom were good enough, because we didn't have the capability to see any further at the time; and they still work as good approximations. Now we can see smaller things, we need more theories to cover it - and the mark of an excellent theory like QM is that it not only covers everything we can now see, it also predicts a few other things that have been since found. Again, each theory is right for its own range. Title: Newtonian Physics (Classical) vs. Quantum Mechanics? Post by: dashylia on Jul 28, 2012 Physics is more like a tool box we have
Screwdrivers (Newton) Wenches (Special and General Relativity) Hammers (Quantum Mechanics) QM is useless for calculating orbital mechanics to get a space probe from earth to say Mars. Guess what you need for that: Good ole Newton You choose the best tool for the job Small and Massive or Energetic: You are SOL we have no theory for this case. (Black Holes, Big Bang) Small and low mass/energy : QM Large - Massive and also near light speed: SR and GR Large - Massive and not a significant fraction of c : Newton |