He participated in the construction of the first atomic bomb: Who is Luis Walter Alvarez?

Luis Alvarez (1911-1988) was a Nobel Prize-winning physicist. He is most famous for his discovery of the iridium layer and for his theory that suggested that the mass extinction of the dinosaurs was caused by an asteroid or comet colliding with Earth. Besides the normal jobs you'd expect from a physics professor, Alvarez has taken on extraordinary projects, such as using cosmic lights to search for secret chambers in the Egyptian pyramid.

Luis Walter Alvarez (June 13, 1911 – September 1, 1988) was an American experimental physicist, inventor, and professor who was awarded the Nobel Prize in Physics in 1968 for his discovery of resonance states in particle physics using the hydrogen bubble chamber. In 2007 the American Journal of Physics commented, "Luis Alvarez was one of the most brilliant and productive experimental physicists of the twentieth century."

Luis Walter Alvarez was born on June 13, 1911, in San Francisco, California. His father, Walter Clement Alvarez, is a doctor and author of numerous medical books.

Luis began his primary education at the Madison School in San Francisco, then continued at San Francisco Polytechnic High School. In 1926, when he was 15, his father changed jobs and he and his family moved to Rochester, Minnesota. Luis graduated from Rochester High School. He then started his Bachelor of Science degree at the University of Chicago in 1928 to specialize in chemistry.

A few years later, his chemistry grades weren't as good as he'd hoped, he was getting a B- and was more interested in physics. For these reasons, he decided to specialize in physics instead of chemistry. He graduated from the physics department in 1932 with a four-year university degree. He then continued his education as a graduate student in Chicago. He received his master's degree here in 1934 and his doctorate in physics in 1936.

Even as a graduate student, Luis Alvarez was at the cutting edge of physics. His doctoral advisor was Arthur Compton. Arthur Compton was the scientist who won the Nobel Prize in Physics in 1927 for his discovery that electromagnetic radiation, such as visible light, has particle-like properties.

In 1932, Alvarez built a set of Geiger counters, a type of particle detector that measures ionizing radiation, to study cosmic rays. Using the data he had collected in 1933, he and Compton published an article in the journal Physical Review that determined that cosmic rays were positively charged particles. Compton gave his young graduate student quite a bit of credit for this work.

After completing his doctorate, Alvarez returned home in 1936 and began working as an experimental physicist at the University of California's Radiation Laboratory at Berkeley.

Alvarez was an avid pilot and had learned to fly in 1933.

In the early 1940s, he invented the microwave phase radar antenna. This invention was a form of radar with the unique precision of ground crew in determining the position of an aircraft in flight. The invention allowed ground crews approaching the runways to give clear instructions to the pilots as the planes prepared for landing.

This system has been particularly useful in situations where visibility is poor, such as in fog or other adverse weather conditions, or where pilots are inexperienced. Alvarez's invention has been used by military and civilian authorities in various countries for decades and greatly improved air safety.

Alvarez's ground approach radar enabled aircraft to land by air traffic controllers in poor visibility.

Alvarez participated in the construction of the first atomic bomb at the Los Alamos Scientific Research Laboratory in 1944-1945.

Nuclear Weapon Detection Projects

In 1943, During World War II, Alvarez was asked whether it was scientifically possible to tell if Germany had its own atomic bomb project. Alvarez knew that research and development for atomic bombs produced radioactive gases like xenon-133. These gases could be detected with the right equipment and Alvarez was an equipment expert. Alvarez said that the plane had to fly over Germany with radiation detectors to detect its warning gases. The flights took place and no evidence was found of Germany's atomic bomb project. Alvarez's method was used after World War II to detect atomic research that took place around the world.

Atom bomb

In 1944, Alvarez traveled to Los Alamos, New Mexico, to work on the Manhattan Project. There he developed an electric detonation method for the plutonium bomb. Together with graduate student Lawrence Johnston, he designed equipment to measure the energy emitted by a nuclear explosion. The two scientists flew to Japan in an observation plane when the bombs were dropped to measure how powerful the nuclear explosions were.

Luis Alvarez devised the first method to discover whether a country is conducting nuclear weapons research. He also developed the first method for measuring how powerful a nuclear explosion was.

Using Radiation from Space to Investigate Pyramid Chambers

In 1967, Alvarez had the ingenious idea that secret chambers in the Egyptian pyramids could be uncovered by using cosmic rays to take an x-ray-type photograph.

He placed a cosmic ray detector in a chamber below the Chephren Pyramid, the second largest of the Giza Pyramids. The speed with which cosmic rays reach the detector will reveal any gaps within the structure of the pyramids. Alvarez was able to examine one-fifth of the pyramid's volume, but could not find a new chamber.

Dinosaur Death by Meteor

Alvarez's son, Walter, became a scientist, just like his father. Walter was a geologist and one day in 1977 he decided to tell his father about a problem. His problem was called the K-T boundary, a gray layer of clay found in rocks.

This clay layer was unusual because it appeared all over the world and was the same age everywhere, so the layer was made at exactly the same time, 65 million years ago, all over the world.

From Luis' point of view, dinosaur fossils could be found in the rocks below the layer, but no dinosaur fossils above the layer. Before this clay layer formed, the dinosaurs and many other life forms that existed later became extinct.

This was not a new problem. The limit and variation of lifestyles on both sides were recognized in Paris in the early 1800s by Georges Cuvier, who suggested that some catastrophe had caused the clay layer. However, Cuvier's ideas lost popularity because the new science of geology was governed by the doctrine of uniformity, that is, the theory that all changes in the earth's geology occur gradually.

After discussing the issue, the father and son set out with a rather modest goal.

They wanted to determine the formation time of the 1 cm deep layer, which Walter was researching in Italy.

Luis decided that the best way to do this was to measure how much of the chemical element iridium was present from the top to the bottom of the layer.

Iridium in the Earth's crust is formed mainly from meteorite impacts, and Luis has calculated the average amount of iridium that comes to Earth from meteorites each year. Comparing iridium levels in the layer with typical iridium arrival rates will show it the time it takes for the layer to form.

Luis asked Frank Asaro, a nuclear chemist at the Lawrence Berkeley laboratory, to determine the iridium content of gray clay samples from the K-T boundary layer. Asaro and his nuclear chemist colleague Helen Michel found a much higher concentration of iridium in the samples than anyone could have imagined. This is much more than can be explained by normal meteorite impacts.

In 1980 the team published their evidence and stated that they found that the K-T boundary layer and the mass extinction event were caused by a large meteorite impact.

Luis Alvarez calculated that a 10 km diameter meteorite traveling at 25 km per second struck the Earth 65 million years ago. This effect sent large amounts of rock dust into the atmosphere and eventually formed a thin gray layer all over the world.

While the dust was in the atmosphere, it blocked the sun's rays, stopped photosynthesis, and cooled the planet.

Without food and heat, the dinosaurs died out.

Most paleontologists are convinced by Alvarez's explanation of the cause of the mass extinction. It is fair to say that the debate between paleontologists and supporters of the Alvarez theory has been fierce and crude. Luis Alvarez said that his opponents had a lot of bad feelings and were not helped. Alvarez was generally cynical and did not care about people who held a different view from his own.

In 1990, two years after Luis Alvarez's death, the Chicxulub crater in the sea off Mexico's Yucatan Peninsula caught the attention of geologists, who agreed that the crater's profile and age-matched Alvarez's estimates.

Luis Alvarez died on September 1, 1988, at the age of 77, from cancer of the esophagus. His memory is kept alive with his first wife Geraldine Smithwick and their children Walter and Jean, and his second wife Janet Landis and their children Donald and Helen.