more subtleties lie in the fact that almost all physical theories were based on the equivalence of the space operator and the time operator except Einstein's field equations of general relativity. For examples, see the following links of equations.
1. Klein-Gordon equation
An equation which hold for spinless particles. The time-dependent form is
where
is the d'Alembertian,
is the wavefunction, m is the mass of the particle, c is the speed of light, and
is h-bar.
2. Schrodinger equation
The time-dependent one-dimensional Schrödinger equation is given by
where i is the imaginary unit,
is the time-dependent wavefunction,
is h-bar, V(x) is the potential, and
is the Hamiltonian operator
3. wave equation
4. Maxwell's equations of radiation
5. Navier-Stokes equation of fluid mechanics
comparing them to Einstein's field equations at