Are Circles Real?

We have reason to think that nature is fundamentally discrete in every aspect, whether it's matter or space or time. And so if that turns out to be correct, that will mean that real numbers are not real. But nevertheless, going back to Plato or others, we can think about perfection in our minds. We can think about the concept of a perfect circle and even the concept of infinity. These things are not real from the standpoint of physics, yet they give us our best understanding of the physical universe.