It depends on your reality of course. It might be the physical reality, whatever that is. Or your own-er reality which might not be logical for example. There are things invariant between realities of course, like the physical experiment and mathematics.
But if your reality upholds logic, you'd have to be very careful as not to take any consequence of your usage of the Fourier transform to be a part of your reality or its description. In which case why use it at all?
Using it is, like I said, an ontological commitment inviting infinities into your system. You may not ascribe them physical meaning, or may renormalize them out, but you can't deny them (do try! though attempts at mathematical ultrafinitism are plagued by problems, whereas finitism, or various less purifying forms of constructive mathematics lead to infinities in just slightly different places).
What you may deny is the reality of the description (that is of you perceiving your reality) whatsoever as Fictionalists do.
I just mean to say mathematical objects do not have to exist in order for them to be efficacious. We may just disagree on the ontology of mathematical objects. Or, I may just be misunderstanding your argument.
But if your reality upholds logic, you'd have to be very careful as not to take any consequence of your usage of the Fourier transform to be a part of your reality or its description. In which case why use it at all?
Using it is, like I said, an ontological commitment inviting infinities into your system. You may not ascribe them physical meaning, or may renormalize them out, but you can't deny them (do try! though attempts at mathematical ultrafinitism are plagued by problems, whereas finitism, or various less purifying forms of constructive mathematics lead to infinities in just slightly different places).
What you may deny is the reality of the description (that is of you perceiving your reality) whatsoever as Fictionalists do.