They haven’t yet discovered the particle of this river we call time. It is flowing, no doubt about it, but it itself is invisible. It is visible only through the movements we make, in our white hair and wrinkled skin and eventually in our death. Death may be deaf and blind, but it is the very climax of the visibility of time. So far the only fair assumption we can make is that time doesn’t have a particle of its own, like gravity has the graviton, but it is the invisible substance of all the particles out there. The river in which they bathe and where they take their being.