  Herein we propose a new numerical technique for solving field theories: the
large momentum frame (LMF). This technique combines several advantages of
lattice gauge theory with the simplicity of front form quantisation. We apply
the LMF on QED(1+1) and on the $\phi^4(3+1)$ theory. We demonstrate both
analytically and in practical examples (1) that the LMF does neither correspond
to the infinite momentum frame (IMF) nor to the front-form (FF) (2) that the
LMF is not equivalent to the IMF (3) that the IMF is unphysical since it
violates the lattice scaling window and (4) that the FF is even more unphysical
because FF propagators violate micro-causality, causality and the finiteness of
the speed of light. We argue that distribution functions measured in deep
inelastic scattering should be interpreted in the LMF (preferably in the Breit
frame) rather than in the FF formalism. In particular, we argue that deep
inelastic scattering probes space-like distribution functions.
