Laws of physics, where are you?

We are used to talking about laws of nature (such as F = ma), but what are they? Or maybe where are they? Here are my answers to someone curious about this on Physics Stack Exchange (with minor edits).     

Q. Are the laws of physics something that exists separately from the universe or is it a description of the physical properties of the universe and objects in it?

A. This is more a philosophy question than a physics one. Laws of physics are a subset of mathematical statements. Mathematical statements are, in turn, a subset of abstract objects.

The ontological status of abstract objects (i.e. whether they exist, and in what way) is a contested question in philosophy. There are prominent philosophers who take opposing views on this.

The position that laws of physics are simply descriptions of what the universe does is a reasonable one and satisfies Occam’s razor. However, that still leaves an interesting philosophical question: what is it that "makes" the universe continue to obey those specific descriptions?

How can an abstract object exist outside of physical reality? Maybe the laws of physics are just how we describe the properties of the universe?

A. I think it's a totally reasonable position to say that physical laws are just descriptions of properties of the universe, in fact I say something very similar in my last paragraph. With regard to abstract objects, as I said there are different views on them, but there is nothing particularly incoherent about the possibility of something existing apart from physical reality. 

Q. Can you give an example of something that doesn't exist in physical reality? 

A. The claim is not that there definitely are entities that actually exist without being in physical reality. My claim is that there could conceivably be such an entity, that there is no incoherence in the possibility of such an entity. I can certainly give you examples of such things: God, ghosts, souls. Maybe they don't actually exist, but there is no incoherence in the possibility of them existing.

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