In a vacuum, all colors of light travel at the same speed, which is approximately 299,792,458 meters per second (often rounded to 300,000 kilometers per second) in the theory of special relativity. This speed is commonly denoted by the symbol 'c' and is the maximum speed at which any form of energy or information can travel in the universe.
The speed of light in a vacuum is a fundamental constant of nature and is the same for all colors of light. The perception of different colors is a result of variations in the wavelength or frequency of light, but these variations do not affect the speed at which light travels.
However, it's worth noting that the speed of light can be different when light travels through a medium other than a vacuum. In materials such as water, glass, or air, the speed of light is slower than in a vacuum. The degree to which light slows down depends on the optical properties of the material, including its refractive index. In these cases, different colors of light can be affected differently, leading to phenomena like dispersion where different colors of light separate and spread out. But within a specific medium, all colors of light still travel at the same speed characteristic to that medium.