* -40 degrees Celsius is the same as -40 degrees Fahrenheit. This is a fun coincidence, but doesn't have anything to do with the fundamental limits of motion.

* Absolute Zero: The temperature at which all motion is theoretically at a minimum is called absolute zero, which is -273.15 degrees Celsius (or 0 Kelvin). At this temperature, particles have the least amount of energy possible and are theoretically completely still.

* Quantum Mechanics: Even at absolute zero, there's a tiny amount of residual energy called zero-point energy. This is due to quantum mechanics and means that even at the absolute coldest temperature, there's still a bit of "jiggle" at the atomic level.

So, to answer your question directly: No, -40 degrees Celsius is not the temperature at which all motion is at a minimum. That temperature is absolute zero, which is much colder.