PhySP19-SS4.2.6– I guess there IS an ultimate limit to “lil dt”. Since time is ∆x / v , turns out ∆x has a limit in our universe (Plank length) and velocity has a limit in our universe (speed of light (c)). It is called a Plank Time. The Planck time is the time it would take a photon travelling at the speed of light to across a distance equal to the Planck length. This is the “quantum of time”, the smallest measurement of time that has any meaning, and is equal to 10^-43 seconds.