Particles like light, specifically photons, cannot be accelerated in a particle accelerator because they are massless and inherently travel at the speed of light (c) in a vacuum. The speed of light is a fundamental constant of nature, dictated by the properties of spacetime and electromagnetic waves. Accelerators can increase the energy of massive particles, but massless particles do not gain speed; they always move at c. The discussion highlights the distinction between mass and speed, emphasizing that the laws of physics prevent massless particles from being accelerated beyond their intrinsic speed. Thus, the nature of light and its constant speed is rooted in the principles of physics.
