You are correct that cosmic rays are particles, specifically high-energy particles that originate from various astrophysical sources. They include protons, electrons, and atomic nuclei, among others. These particles exhibit both particle-like and wave-like behavior, which can be explained by the principles of quantum mechanics and the concept of matter waves.
According to the matter wave theory, also known as wave-particle duality, all particles, including cosmic rays, possess wave-like properties. The matter wave theory is a fundamental concept in quantum mechanics that describes particles as having both particle and wave characteristics.
In the case of cosmic rays, their wave-like behavior is associated with their quantum nature. According to the de Broglie hypothesis, proposed by Louis de Broglie, every particle is also associated with a wave that is determined by its momentum. This wave is called the matter wave or de Broglie wave.
The matter wave of a particle, such as a cosmic ray, is related to its momentum and wavelength. The wavelength of the matter wave is inversely proportional to the momentum of the particle. This implies that particles with higher momentum, such as high-energy cosmic rays, have shorter wavelengths associated with their matter waves.
Although cosmic rays are considered particles, their wave-like behavior can be observed in certain experiments. For example, in particle accelerators, high-energy cosmic rays can undergo interference and diffraction effects similar to what is observed with other particles, such as electrons or protons. These phenomena are consistent with the wave nature of particles described by the matter wave theory.
In summary, cosmic rays are particles, but they exhibit wave-like behavior due to the principles of quantum mechanics and the concept of matter waves. The matter wave theory provides a framework to understand the wave-particle duality of cosmic rays and other particles.