who did such experiments?
UNANSWERABLE
who discovered the speed of light in a vacuum Witelo what is the numerical value of it? As a dimensional physical constant, the numerical value is different for different unit systems. how important is it in the field of physics? It is independent both of the motion of the wave source and of the inertial frame of reference of the observer. were there any experiments conducted to discover something faster than light? Yes, but they do not travel fast than light
wiki:19581006
Speed of light [SEP] Faster-than-light observations and experiments
There are situations in which it may seem that matter, energy, or information travels at speeds greater than "c", but they do not. For example, as is discussed in the propagation of light in a medium section below, many wave velocities can exceed "c". For example, the phase velocity of X-rays through most glasses can routinely exceed "c", but phase velocity does not determine the velocity at which waves convey information. If a laser beam is swept quickly across a distant object, the spot of light can move faster than "c", although the initial movement of the spot is delayed because of the time it takes light to get to the distant object at the speed "c".