* Speed of light: The fastest thing we know of in the universe is light. It travels at approximately 299,792,458 meters per second (186,282 miles per second). Nothing with mass can travel at the speed of light.
* Tachyons: Some theories suggest the existence of particles called tachyons that always travel faster than light. However, there's no scientific evidence to support their existence.
* Cosmic rays: Extremely energetic particles from space, like cosmic rays, can travel at nearly the speed of light.
So, the answer depends on what you consider to be a particle and what you mean by "fastest."
If we're talking about known, confirmed particles, then light is the fastest. If we're considering hypothetical particles, then tachyons could potentially be faster than light.
