Speed of light has also been shown in experiment. It should even be possible for the group velocity to become infinite or negative, with pulses travelling instantaneously or backwards in time. None of these options, however, allow information to be transmitted faster than "c". It is impossible to transmit information with a light pulse any faster than the speed of the earliest part of the pulse (the front velocity). It can be shown that this is (under certain assumptions) always equal to "c". It is possible for a particle to travel through a medium faster than the phase velocity of light in that
Symbol table Symbol table In computer science, a symbol table is a data structure used by a language translator such as a compiler or interpreter, where each identifier (a.k.a. symbol) in a program's source code is associated with information relating to its declaration or appearance in the source. Symbol table stores the information related about the symbol. A symbol table may only exist in memory during the translation process, or it may be embedded in the output of the translation, such as in an ABI object file for later exploitation. For example, it might be used during an interactive debugging session, or