They say the UV infinities appear because we do not know the real physics of sho

Question

They say the UV infinities appear because we do not know the real physics of short distances and initially we introduce it wrong. OK, but after renormalizations, what physics does remain? Do we replace the unknown/wrong physics with certain/right one? Can anybody describe it without appealing to unphysical bare particles? Have we an idea about the real electron from QED? If so, why we cannot use it as the input to construct a reasonable theory from the very beginning?

P.S. Moderators, please do not close my questions before they are answered, let people answer.

Explanation / Answer

Let us take standard fluid dynamics as a model of continuum media physics. It is obvious what is its "short-distance" physics isn't it? These are atoms and molecules. Let's apply your questions to this case -- suppose that we know nothing about atoms and molecules. in that case we can still use hydrodynamics, don't we?

Do we replace the unknown/wrong physics with certain/right one?

What is "wrong" and "right" physics in a first place? If your hydrodynamics predicts physical phenomena in it's range of validity then I'm free to call it "right". Even if it says nothings about atoms. Anything else is a philosophy.

Can anybody describe it without appealing to unphysical bare particles?

Can anybody describe hydrodynamics without appealing to "unphysical" continuum medium? Yes -- if one knows about atoms. If one doesn't know then one can try to speculate about underlying theory. But it doesn't render hydrodynamics useless and "wrong".

Have we an idea about the real electron from QED? Why we cannot use it as the input to construct a reasonable theory from the very beginning?

Have we an idea about "real" stream of water? It is made of atoms, right? So in this particular case there is no "real" stream of water at all. That's why we cannot use it as the input to construct a reasonable theory from the very beginning.

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