A very nice essay on the fundamental problems in physics. Like the fact that it doesn't all fit together. We have islands of knowledge with vast chasms between them. On these islands we can solve the most intricate problems. Between the islands we know practically nothing.
Physics is the most fundamental of the natural sciences; it explains Nature at its deepest level; the edifice it strives to construct is all-encompassing, free of internal contradictions, conceptually compelling and—above all—beautiful. The range of phenomena physics has explained is more than impressive; it underlies the whole of modern civilization. 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 Bruegel’s 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.Well it is not quite as bad as all that. We have a perfectly good explanation. Statistics. But statistics is not deterministic. It only tells you the most likely answer and the range of answers possible (in a "reasonable" amount of time).
Of course many grand issues remain unresolved at the frontiers of physics: What is the origin of inertia? Are there extra dimensions? Can a Theory of Everything exist? But even at the undergraduate level, far back from the front lines, deep holes exist; yet the subject is presented as one of completeness while the holes—let us say abysses—are planked over in order to camouflage the danger. It seems to me that such an approach is both intellectually dishonest and fails to stimulate the habits of inquiry and skepticism that science is meant to engender.
In the first week or two of any freshman physics course, students are exposed to the force of friction. They learn that friction impedes the motion of objects and that it is caused by the microscope interaction of the two surfaces sliding past one another. It all seems quite plausible, even obvious, yet regardless of any high falutin’ modeling, with molecular mountain ranges resisting each other’s passage or running-shoe soles binding to tracks, friction produces heat and hence an increase in entropy. It thus distinguishes past from future. The increase in entropy—the second law of thermodynamics—is the only law of Nature that makes this fundamental distinction. Newton’s laws, those of electrodynamics, relativity … all are reversible: None care whether the universal clock runs forward or backward. If Newton’s laws are at the bottom of everything, then one should be able to derive the second law of thermodynamics from Newtonian mechanics, but this has never been satisfactorily accomplished and the incompatibility of the irreversible second law with the other fundamental theories remains perhaps the greatest paradox in all physics. It is blatantly dropped into the first days of a freshman course and the textbook authors bat not an eyelash.
And of course there is the measurement problem. We only know things to be "true" to the level we can measure them. Because with greater precision new things often show up. And there may be things we will never know because they are so far down in the noise. Not to mention quantum uncertainty. Which brings up a whole host of question in and of itself.
Read the whole thing.