The theory of special relativity states that one dimension of time and three dimensions of space are interwoven together as one. Space-time is considered to be one single unit. The said unity between the space and time poses a question of the possibility of time travelling.
Light and sound are natural phenomena that have fascinated scientists since ancient times. Their varying speeds too have been subject to painstaking hours of experimentation, exploration and enquiry, before scientists were able to obtain concrete information about it.