Convert Millimeter/Hour (mm/h) to Speed of Light (c) instantly.
About these units
Millimeter/Hour (mm/h)
A millimeter per hour is extraordinarily slow, used in geology, meteorology, and materials science to measure phenomena like soil creep, tectonic plate micro-motion, or extremely light precipitation (drizzle). In manufacturing, mm/h may describe slow deposition rates in thin-film fabrication or high-precision milling processes. Despite seeming negligible, speeds measured in mm/h can accumulate into significant changes over weeks, months, or years—making them essential for long-term studies.
Speed of Light (c)
The speed of light in a vacuum, denoted c, is exactly 299,792,458 m/s, one of the most fundamental constants of physics. Light speed defines the structure of spacetime, the upper limit for classical information transfer, and the basis for relativity. Time dilation, length contraction, and mass-energy equivalence (E = mc²) all arise from the invariance of c. In astronomy, the speed of light is used to define light-years, measure cosmic distances, and synchronize observations across telescopes. In communication technology, optical networks rely on light-speed propagation through fiber, albeit slightly slower than in vacuum. c is not just a speed—it is a cornerstone of the physical universe.