Which type of radiation is characterized by high-energy electromagnetic waves that lack mass?

Gamma radiation is indeed characterized by high-energy electromagnetic waves that lack mass. This form of radiation is a type of gamma rays, which are produced in the decay of radioactive atoms and nuclear reactions. Being electromagnetic waves, gamma radiation travels at the speed of light and has no mass or charge, distinguishing it from particles like alpha and beta radiation.

To provide a clearer picture, gamma rays have the highest frequency and energy among electromagnetic waves, which includes other types of radiation like visible light, X-rays, and radio waves. This high energy allows gamma rays to penetrate various materials much more effectively than lower-energy radiation types, making them significant in fields such as medicine and industry, particularly in cancer treatment and sterilization processes.

In contrast, X-ray radiation, while also high-energy and electromagnetic, is typically produced by the interaction of high-energy electrons with matter rather than through nuclear decay. Radioactivity refers to the process of decay that produces various types of radiation including alpha, beta, and gamma radiation. Alpha radiation consists of particles with mass (helium nuclei) and is therefore completely different from high-energy electromagnetic waves.