Are there laws of physics?

Among all academic disciplines, the sciences have a reputation for being cutting-edge. A classical historian who demonstrates intimate familiarity with 18th & 19th century French, Italian, and German scholarship is considered impressive. A philosopher not familiar with the work of at least a few Greeks who lived over 2,000 years ago is considered lacking. A scientist, on the other hand, likely works in a field that didn’t exist a century ago and if it did, studying work in the field at or before that time is historical or philosophical research, not scientific. In fact, a single scientific study can render hundreds of others obsolete, can found a new field, or provide a method that becomes central to fields across the sciences.

To some extent, there is a fair amount of justification for the relative ignorance among both specialists and laypersons of older work in any given scientific field- just not enough. This will become more important in subsequent posts, but here it is perhaps sufficient to point to the use of terms for concepts central to the sciences: “law”, “theory”, “hypothesis”, etc. Outdated terminology permeates statistics, including the most frequently used measures, and radically distinct usage of key terms like “hypothesis” is pervasive in all scientific literature. Most of the time, this doesn’t matter. One can thoroughly understand the logic underlying Pearson’s “product-moment” correlation r and have no idea what “moment” refers to and nobody confuses the hypothesis testing a computer does in machine learning with scientific hypotheses. However, there are plenty of scientists and far, far more non-scientists who think that the “laws of physics” isn’t a combination of the antiquated term “law” and a misunderstanding of modern physics.

The most well-known scientific “laws” are wrong. Take the “law of gravity”: this is perhaps the best known law and yet it isn’t just describing something that doesn’t exist, it refers to one of the most important, unsolved problems in modern physics. The general theory of relativity, which is amazingly successful at the macro scale, breaks down at the subatomic (and arguably atomic) scale. There is no “law of gravity” in relativistic physics. Einstein’s equations account for gravity, but do so without gravitation other than some complex differential equations, altering our notions of space and time, and introducing paradoxes like closed timelike curves. That said, the theories of special and relativity are not so different from classical physics (and, in fact, are often categorized as such). Sure, things don’t move for the same reasons according to the general theory of relativity, and it entails some (at least potentially) mind-boggling phenomena, but Einstein’s insistence that God doesn’t play dice (not an endorsement of theology but a criticism of indeterminism) hearkens back to the deterministic philosophy of Laplace and Newton’s clock-like cosmos. This is why Einstein dedicated years, and years, and years trying to show that the modern physics he was essential in founding was fundamentally flawed.

Einstein was the lead author of a 1935 paper commonly referred to as EPR (the latter two letters referring to the surnames of Einstein’s coauthors). The purpose of this paper was to argue that quantum mechanics (QM) entailed that which couldn’t be, and thus wasn’t really physics. To simplify, Einstein and coauthors argued that QM entailed instantaneous causal relationships (which entails faster-than-light effects, completely contradicting special relativity and challenging the very notion of causation). To actually simplify, Einstein argued that if QM is true, something can cause something else instantaneously regardless of distance. If someone accidently knocks a class of milk over, and it spills, there’s no point crying over spilt milk. If someone moves their hand 11 kilometers away from a glass of milk and it causes the milk to spill, there’s reason to worry.

There are causal paradoxes that relativity entails, but this is nothing compared to the incompatibilities between the two most successful theories of modern physics (relativity and quantum physics). Attempts to unify these consist mostly of mathematical solutions we can’t test. Worse still, nobody understands how quantum mechanics (and by extension quantum field theory, quantum chromodynamics, particle physics, etc., are) correspond(s) to reality. The authors of Bohmian Mechanics: The Physics and Mathematics of Quantum Theory (Fundamental Theories of Physics) make an interesting (if problematic and, in my opinion, flawed) point. They note that until quantum physics, physicists didn’t labor over how their notations corresponded to physical reality. Sure, the same entity could weigh x pounds but y kilograms, but regardless of the number and the notation it was still weight. Same for speed. In “physics speak”, observable properties of physical systems like momentum, position, velocity, mass, etc., were values that corresponded reality in very obvious ways. Nobody wondered how the coordinate values representing the position of a comet or a ballista described where the comet or ballista was in space.

Quantum physics changed all this. It is irreducibly statistical. In laypersons terms, the laws of quantum physics aren’t laws but probabilistic statements about the state of physical systems that aren’t physical and that have multiple, incompatible states. They are laws that say “given that we prepared some experiment in x way, we should expect that y possibility is more likely than z but that there could be infinitely many others”. This is like saying the law of gravity ensures things fall, except when it makes them hover, zoom to the left, fly up, or has no effect whatsoever.

Not much of a law.

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