Question

Robert B. Laughlin, A Different Universe states the following concerning the relationship between superconductivity and quantum field theory. I do not understand why he says the microscopic equations of quantum mechanics encrypted in the field theory are different from those of the real material and therefore wrong. Could someone explain?

Reductionist ideology has another fascinating manifestation in superconductivity theory that I call quantum field theory idolatry. Quantum field theory, a body of mathematics that grew out of studies of elementary particles, is commonly taught after conventional quantum mechanics as a special language for working in that subject—and also as kind of superior way of thinking. It is actually not a new way of thinking but simply a restatement of quantum mechanics in the context of the special limitations and conditions appropriate to the vacuum of space. These conditions make the formalism elegant and fun to learn—at least for mathematical types such as myself—but they also make it easy to hide the essence of a thing through manipulation. Sleights of hand can make some physical behavior appear to be caused by field theory when it is actually being caused by the manipulation itself. Shortly after the Bardeen-Cooper-Schrieffer theory was introduced, the language of quantum fields was discovered to be particularly well suited for describing important properties of superconductors—notably the supercurrents themselves, the Meissner effect, the above-threshold conductivity, and the collective sloshing motions of the electrons called plasma oscillations—precisely because it allowed one to postulate one’s way around messy, ultimately unimportant detail and get quickly to the meat of the matter. This eventually led to the practice of explaining all of superconductivity using field theory, and thus indirectly to the idea that quantum fields cause superconductivity. Even today one will find a great many people who secretly believe this. It is ridiculous—like believing that the weather is caused by the price of corn. In fact, quantum field theory works because the emergent universality of superconductivity makes it work, not the other way around. The microscopic equations of quantum mechanics encrypted in the field theory are different from those of the real material and therefore wrong. The only way one can start from wrong equations and get the right answer is if the property one is calculating is robustly insensitive to details, i.e., is emergent. Thus the lesson from superconductivity is actually not that quantum field theory is a superior computational technology but that quantum fields can themselves emerge.

Answer 1

The author of 'A Different Universe' criticizes the use of quantum field theory in superconductivity theory, arguing that the microscopic equations of quantum mechanics in field theory are different from the equations of real superconducting materials.

Step-by-step explanation:

The author of 'A Different Universe' criticizes the use of quantum field theory in superconductivity theory, stating that it is a restatement of quantum mechanics with limitations and conditions applicable to the vacuum of space. The author argues that the microscopic equations of quantum mechanics in field theory are different from the equations of real materials. Therefore, the author believes that field theory is wrong in describing the behavior of real superconducting materials.