While free and weakly interacting particles are well described by a second-quantized nonlinear Schrödinger field, or relativistic versions of it, with various approximations, the fields of strongly interacting particles are governed by effective actions, whose quadratic terms are extremized by fractional wave equations. Their particle orbits perform universal Lévy walks rather than Gaussian random walks with perturbations.PACS numbers: 95.35+d.04.60,04.20C,04.90 Quantum-mechanical physics is explained with high accuracy by Schrödinger theory. The wave equation for many particles can convenienty be reformulated as a second-quantized field theory, with an action that is the sum of quadratic and an interacting termwhere the term A 2 has typically the formwith D being the space timension, m the mass, and V (x) some external potential. The interaction term A int may be approximated in molecular systems by a fourth-order term in the fieldwhere V 12 (x, x ′ ) is some two-body potential. If relativistic velocities are present, the field is generalized to a scalar Klein-Gordon field, or a quantized Dirac field. In molecular physics, the fourth-order term is due to the exchange of a minimally coupled quantized photon field and is proportional to e 2 , where e is the electric charge. The field equations may be studied with any standard method of quantum field theory, and corrections can be derived using perturbation theory in powers of α ≡ e 2 / ≈ 1/137. Since α is very small, this appeoch is quite successful.If time is continued analytically to imaginary values t = iτ , one is faced with the so-called Euclidean version of quantum field theory. Then perturbation theory may be understood as developing a theory of particle physics from an expansion around Gaussian random walks. Indeed, the relativistic scalar free-particle propagator of mass m in D + 1-dimensional euclidean energymomentum space p µ = (p, p 4 ), has the formwhere the energy has been continued analytically to p 4 = −iE. The Fourier transform of e −s(p 2 +p 2 4 ) is the distribution of Gaussian random walks of length s in D + 1 euclidean dimensionswhich makes the propagator (4) a superposition of such walks with lenghts distributed like e −sm -3]. This propagator is the relativistic version of the free-field propagator of the action (2). The second-quantized field theory described by (1) accounts for grand-canical ensembles of orbits with their two-body interactions [4].Gaussian random walks are a natural and rather universal starting point for many stochastic processes. For instance, they form the basis of the most important tool in the theory of financial markets, the Black-Scholes option price theory [5] (Nobel Prize 1997), by which a portfolio of assets is hoped to remain steadily growing through hedging. In fact, the famous central-limit theorem permits us to prove that many independent random movements of finite variance always pile up to display a Gaussian distribution [6].However, since the last stock market crash and the still ongoing financial cris...