Physicist Tony Rothman said terrible things about all of Physics in the 2011 May-June issue of American Scientist in the article "The Man Behind the Curtain: Physics is not always the seamless subject it pretends to be"Of course the books say what is spinning -- the electron spins. What they do not do, and cannot do, is to give a classical model of a mechanical spinning electron to visualize. Quantum mechanics shows that the electron behaves differently from those classical objects, but there really is an electron and it really does spin.
"Nevertheless, as a physicist travels along his (in this case) career, the hairline cracks in the edifice become more apparent, as does the dirt swept under the rug, the fudges and the wholesale swindles, with the disconcerting result that the totality occasionally appears more like Bruegels Tower of Babel as dreamt by a modern slumlord, a ramshackle structure of compartmentalized models soldered together into a skewed heap of explanations as the whole jury-rigged monstrosity tumbles skyward" ...
"One doesn't have to go so far in quantum theory to be confused. The concept of electron "spin" is basic to any quantum mechanics course, but what exactly is spinning is never made clear. Wolfgang Pauli, one of the concept's originators, initially rejected the idea because if the electron was to have a finite radius, as indicated by certain experiments, then the surface would be spinning faster than the speed of light. On the other hand, if one regards the electron as a point particle, as we often do, then it is truly challenging to conceive of a spinning top whose radius is zero, not to mention the aggravation of infinite forces"
Then he attacks the 2-slit experiment:
"....Rather than describing how the light interacts with the slits, thus explaining why it behaves as it does, we merely demand that the light wave meet certain conditions at the slit edge and forget about the actual forces involved. The results agree well with observation, but the most widely used of such methods not only avoids the guts of the problem but is mathematically inconsistent"
He goes on and on...attacking Lagrangian mechanics, ....etc
"The great swindle of of introductory physics is that every problem has an exact solution. Not only that, students are expected to find it.
He also complains that some systems can be solved numerically, but not in closed-form exact formulas. Some are also chaotic, making long-term prediction an impossibility. And real-life problems are more complicated that the over-simplified textbook examples.
That essay concludes:
“Explanation” in physics generally means to find a causal mechanism for something to happen, a mechanism involving forces, but textbook optics affords no such explanation of slit experiments. ...Some people argue that Newtonian gravity theory is not really an "explanation" of the solar system, because it fails to give a causal mechanism for how the mass of the Sun exerts its force on the planets. I thought that was where Rothman was going in the penultimate paragraph, but then he seems to say that physics does not require any such explanation.
Such examples abound throughout physics. Rather than pretending that they don’t exist, physics educators would do well to acknowledge when they invoke the Wizard working the levers from behind the curtain. Even towards the end of the twentieth century, physics was regarded as received Truth, a revelation of the face of God. Some physicists may still believe that, but I prefer to think of physics as a collection of models, models that map the territory, but are never the territory itself. That may smack of defeatism to many, but ultimate answers are not to be grasped by mortals. Physicists have indeed gone further than other scientists in describing the natural world; they should not confuse description with understanding.
It seems entirely appropriate to me for physics textbooks to explain what they can, and not speculate much about what they cannot explain. Maybe after discussing the hydrogen atom, the book should say that a carbon atom is a whole lot more complicated. But isn't that obvious?
So of course physics textbooks are going to give particle and wave descriptions of light, and give the quantum mechanics description. If you find that intellectually dissatisfying, that's too bad, because that is the best we can do.
Like other physics expositors, he cannot resist talking about Einstein, and mentions:
Einstein did not consider his theory of gravitation — general relativity — complete until he could derive his field equations from an action, a feat that the mathematician David Hilbert accomplished five days before Einstein himself.I am a little surprised he phrases it that way, because there is no evidence that Einstein derived the field equations from an action. Hilbert and Einstein had many meetings in 1915 before they each published those general relativity papers. Hilbert's paper describes the action, and Einstein's 5-days-later paper does not.
The way it appears to me, Einstein was tentative about general relativity until two things happened in the fall of 1915: (1) he learned that Hilbert could use a covariant action to derive essentially the same field equations that Grossmann published in 1913; and (2) he was able to use those equations to extend Poincare's analysis of the relativistic effect on Mercury's orbit. Einstein then had to hurry up and publish so he could claim full credit, or else Hilbert would get credit.