Final answer:
Light does not have mass because according to Einstein's Theory of Relativity and confirmed by experiments, an object with mass cannot reach the speed of light, c. Light travels at this constant speed in a vacuum, reinforcing the concept that it must be massless.
Step-by-step explanation:
Does Light Have Mass?
One of the foundational aspects of modern physics is the behavior and characteristics of light. According to Einstein's Theory of Relativity and Maxwell's equations, light travels at a constant speed denoted by c in a vacuum, which is approximately 3.00×108 m/s. An important consequence of these principles is that an object with mass cannot reach the speed of light. Therefore, since light travels at this ultimate speed c, it must be massless. This conclusion was reached after detailed experiments and theoretical work by scientists who found that the speed of light is independent of the motion of the source or the observer, rejecting the necessity of the ether as a medium for light to travel and contradicted the idea that velocities add like simple vectors as per Newton's laws. Instead, everyone observes light to move at speed c regardless of their movement relative to each other or the source of light.
In summary, light does not have mass because if it did, it would not be able to travel at the speed of light. This understanding is encapsulated by Einstein's theory which has been confirmed by numerous experiments. Therefore, the correct answer to the question is b) No, light cannot have mass because it travels at c.