Laplace transform as rotation. In what space?

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The discussion explores the concept of the Laplace transform as a generalization of the Fourier transform, specifically viewing it as a rotation of basis in the space of complex-valued functions. It questions whether the Laplace transform can be interpreted similarly to the Fourier transform, transitioning from a delta-functions basis to a new basis of e^{(\alpha + i\beta) t}. The conversation highlights the significance of analytical continuation and mentions Wick rotation as a potential link between the two transforms. Additionally, it notes the specific paths of summation in the direct and reverse transforms. Overall, the thread seeks to clarify the mathematical foundations and implications of these transformations in complex function spaces.
mclaudt
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Sorry for thumb terminology, I just would like to grasp the main idea, as a physicist, without unnecessary complications, associated with system of axioms and definitions.

Fourier transform can be seen as rotation of basis in space of all complex-valued functions from basis of delta-functions to a new basis of waves e^{i\omega t}.

Laplace transform can be seen as generalization of Fourier transform to complex frequencies. Is it correct to see the Laplace transform as a rotation of basis in space of complex-valued functions of complex argument, from delta-functions basis to a new basis of e^{(\alpha + i\beta) t}and, if it is so, what is the basis in that space, and why does summation go only along line (-\infty, +\infty) in direct transform and (\gamma - i\infty, \gamma + i\infty) in reverse transform?
 
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There is also an operation known as Wick rotation, it is a candidate to interpret the interconnection between Fourier and Laplace, it could be interesting if they both constitute some beautiful scheme.
 
It seems that the key point is the analytical continuation. The raw form of Laplace transform is F(s) = \int_{ℂ}e^{-su}f(u)du, where f(u) is analytical continuation of f(t) to complex plane. And in that case the Laplace transform will be the rotation of basis in {f(u)} space of complex functions of complex argument, just as Fourier transform is the rotation of basis in {f(t)} space of complex functions of real argument, and integral is in both cases just a generalization of matrix multiplication to infinite dimension.

It's just guess, I'm not sure if it is correct to define F(s) that way.
 

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