American (with antecedents in Spain and Cuba)
About Luis Alvarez
Luis Alvarez is a good example of how an "amateur" can have a profound impact on the world of paleontology. We put the word "amateur" is in quotation marks because, before he turned his attention to the extinction of the dinosaurs 65 million years ago, Alvarez was a highly accomplished physicist (in fact, he won the Nobel Prize in Physics in 1968 for his discovery of the "resonance states" of fundamental particles). He was also a lifelong inventor, and was responsible for (among other things) the Synchrotron, one of the first particle accelerators used to probe the ultimate constituents of matter. Alvarez was also involved in the later stages of the Manhattan Project, which yielded the nuclear bombs dropped on Japan at the end of World War II.
In paleontology circles, though, Alvarez is best known for his late 1970's investigation (conducted with his geologist son, Walter) into the K/T Extinction, the then-mysterious event 65 million years ago that killed the dinosaurs, as well as their pterosaur and marine reptile cousins. Alvarez's working theory, inspired by his discovery of a clay "boundary" in Italy separating geologic strata from the Mesozoic and Cenozoic Eras, was that the impact of a large comet or meteor threw up billions of tons of dust, which circled around the globe, blotted out the sun, and caused global temperatures to plunge and the earth's vegetation to wither, with the result that first plant-eating and then meat-eating dinosaurs starved and froze to death.
Alvarez's theory, published in 1980, was treated with intense skepticism for a full decade, but was finally accepted by the majority of scientists after scattered iridium deposits in the vicinity of the Chicxulub meteor crater (in present-day Mexico) could be traced to the impact of a large interstellar object. (The rare element iridium is more common deeper in the earth than on the surface, and could only have been scattered in the patterns detected by a tremendous astronomical impact.) Still, the widespread acceptance of this theory hasn't prevented scientists from pointing to ancillary causes for the extinction of the dinosaurs, the most likely candidate being the volcanic eruptions triggered when the Indian subcontinent slammed into the underside of Asia at the end of the Cretaceous period.