Doesn't it depend on your precise definition of Fractal. In nature they're not self-similar repetitions at altered scale but approximate the same¹. There is always a limitation in nature of resolution (lumpiness of atoms) just as no true circle can exist in nature (at least in our realm Plato², please correct me if I'm wrong).
So technically most (all I think) fractals do not occur extent in reality but only the mathematical description of them occurs.
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Doesn't it depend on your precise definition of Fractal. In nature they're not self-similar repetitions at altered scale but approximate the same¹. There is always a limitation in nature of resolution (lumpiness of atoms) just as no true circle can exist in nature (at least in our realm Plato², please correct me if I'm wrong).
So technically most (all I think) fractals do not occur extent in reality but only the mathematical description of them occurs.
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¹ note the precise definition of "similar" in geometry, http://en.wikipedia.org/wiki/Similarity_%28geometry%29. ² I can't recall Plato's take on [perfect] forms of biological "shapes" like trees and such.