Luis Alvarez was a physicist and Nobel Prize winner who made significant contributions to the fields of particle physics, nuclear physics, and cosmic ray research. He is best known for his work on the development of the hydrogen bubble chamber, which allowed scientists to observe the paths of subatomic particles. He also developed the Alvarez effect, which explains how cosmic rays can cause changes in the Earth's atmosphere. He was awarded the Nobel Prize in 1968 for his work in particle physics.