Prime Hex B (2013) is a time-based light installation by Marius Watz in which fluorescent tubes mounted in a hexagonal grid structure are switched on and off according to individually assigned time intervals (e.g. on for 7 seconds, off for 7 etc.). All assigned intervals are unique prime numbers, giving the installation its name and significantly affecting the behavior of the installation.
As a consequence of the combination of simple timing logic and prime number intervals the installation will exhibit a binary on/off animation behavior. If given enough time the system is mathematically guaranteed to iterate through every possible permutation of on/off grid elements, the sequence being predetermined by the distribution of primes among elements. The primes also ensure that the system will have a very long non-repeating interval (calculated by factoring the intervals of all elements.) Occasionally local patterns may appear that look recognizable or at the very least non-random and pre-programmed (and thus intentional). In reality, such patterns are a matter of mathematical necessity.
The origin of the Prime series was the 2010 public art commission for the Bybanen light rail in Bergen, leading to the installation of 6 Prime grids in varying sizes in one 2-km long tunnel using LED lighting elements and electronic time relays. The prime number logic was chosen to reduce repetition and eliminate the inevitable bias of pre-programmed content.