The equations of motion governing the dynamics of microscopic processes, such as the motion of atoms, are inherently time reversible. This means that the trajectory of a particle has the same shape if time is reversed, the particle just travels in the opposite direction with opposite forces. You can prove this simply by substituting "-dt" for "dt" in Newton's Second Law.

Now, the dynamics of atoms and molecules are known to follow Newton's Second Law; look up the millions of papers published on Molecular Dynamics simulations and their agreement with experiment.

If that's the case, then why are macroscopic processes, such as heat conduction (which is just a bunch of atoms and molecules following trajectories according to Newton's Second Law), irreversible?

Where the fuck does entropy generation come from?