Abstract
We learn from Heisenberg's Uncertainty Principle (HUP) that energy and time are two complementary parameters, just as the position and the momentum of a particle. From Heisenberg's equation, concerning time and energy, it comes out that as one of the two parameters increases the other will decrease proportionally.If we apply the HUP to the Electromagnetic Waves (EMWs) we have that the higher the energy an EMW carries, the shorter its time of travelling and hence the higher the speed of the wave.The few day long EM swarm, related to the EMWs and emitted by Gamma Ray Bursts (GRBs) in just 20 seconds, may represent a demonstration of the different propagation speeds of EMWs depending on the different energy they carry.