Lawrence Bragg facts for kids
Quick facts for kids
Lawrence Bragg
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Lawrence Bragg in 1915
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William Lawrence Bragg
31 March 1890 Adelaide, South Australia
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| Died | 1 July 1971 (aged 81) Waldringfield, Ipswich, Suffolk, England
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| Education | St Peter's College, Adelaide |
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| Known for | X-ray diffraction X-ray spectroscopy X-ray microscopy Bubble raft Bragg's law Bragg-Gray cavity theory Bragg-Williams approximation |
| Spouse(s) | Alice Hopkinson (1899–1989) |
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| Fields | Physics |
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| Other notable students | William Cochran |
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He was the son of W. H. Bragg. The PhD did not exist at Cambridge until 1919, and so J. J. Thomson and W. H. Bragg were his equivalent mentors.
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Sir William Lawrence Bragg (born March 31, 1890 – died July 1, 1971) was a brilliant scientist from Australia who became a British physicist. He is famous for discovering something called Bragg's law of X-ray diffraction in 1912. This law is super important for figuring out the hidden structures of crystals.
In 1915, he won the Nobel Prize in Physics with his father, William Henry Bragg. They won for their work on understanding crystal structures using X-rays. Lawrence Bragg was only 25 years old when he received the award, making him the youngest Nobel laureate in physics ever! Later, he was knighted in 1941.
Bragg was also the director of the Cavendish Laboratory in Cambridge when the famous discovery of the structure of DNA was made by James Watson and Francis Crick in 1953.
Contents
Biography of Lawrence Bragg
Early Life and Education
William Lawrence Bragg was born in Adelaide, South Australia. His father, Sir William Henry Bragg, was a professor of mathematics and physics at the University of Adelaide. His mother was Gwendoline Todd.
Lawrence went to school at St Peter's College, Adelaide. At just 16, he started studying mathematics, chemistry, and physics at the University of Adelaide, graduating in 1908. That same year, his family moved to England because his father got a job at the University of Leeds.
In 1909, Lawrence went to Trinity College, Cambridge. Even though he was sick with pneumonia during his entrance exam, he still earned a major scholarship in mathematics. He later switched to physics and graduated with top honors in 1911. He also loved collecting shells and found a new species of cuttlefish, which was named Sepia braggi after him.
Discovering Bragg's Law
At the time, scientists weren't sure if X-rays were particles or waves. Max von Laue showed that X-rays were waves by shining them through a crystal and seeing a pattern of spots.
In 1912, while still a student at Cambridge, Lawrence Bragg had a brilliant idea. He realized that when X-rays hit a crystal, they would only create clear patterns if they hit the layers of atoms inside the crystal at specific angles. If the angle was just right, the X-rays would bounce off the layers and line up perfectly, creating a bright spot on a film.
From this idea, he developed the simple Bragg equation. This equation connects the wavelength of the X-ray, the distance between the atomic layers in the crystal, and the angles at which the X-rays would reflect.
His father built a special machine to measure these reflections. Together, they used Bragg's equation to figure out the distances between atoms in many simple crystals. This work was a huge step forward in understanding the tiny structures of materials.
World War I and Sound Ranging
When World War I began, Bragg joined the Royal Horse Artillery. In 1915, he was asked to help the Royal Engineers develop a way to find enemy artillery guns by listening to their firing sounds. This was called "sound ranging."
It was a tough problem because the loud booms of the big guns were too low for microphones to pick up. After many tries, Bragg and his team invented a special detector that could sense the air waves from the gunshots. This invention was very successful and was used by British and American armies during the war.
For his important work, he received the Military Cross and was made an Officer of the Order of the British Empire. Sadly, his brother was killed in the war around the same time he and his father won the Nobel Prize.
Working at Universities
After the war, from 1919 to 1937, Bragg worked as a professor at the Victoria University of Manchester. He continued his research on crystals, often working with his father. They found ways to use X-rays to understand even more complex crystal structures, like those of silicates.
In 1937, he became the director of the National Physical Laboratory. Then, in 1938, he became the director of the famous Cavendish Laboratory at the University of Cambridge.
During World War II, Bragg advised on sonar and sound ranging, still using the methods he helped develop. He was knighted in 1941, becoming Sir Lawrence.
After the war, he reorganized the Cavendish Laboratory into smaller research groups. He believed that small teams of scientists worked best. He also helped create the International Union of Crystallography.
The Discovery of DNA
At the Cavendish Laboratory, Bragg supported a young researcher named Max Perutz, who was trying to figure out the structure of large biological molecules like haemoglobin. Bragg believed this was a "gallant attempt" and helped secure funding for the work.
This research group eventually led to one of the biggest scientific discoveries of the 20th century: the structure of DNA. In 1953, James Watson and Francis Crick, working under Bragg's direction at the Cavendish, figured out that DNA was a double helix.
Bragg was the one who announced this groundbreaking discovery to the world. He later nominated Crick, Watson, and Maurice Wilkins for the 1962 Nobel Prize for their work on DNA. He also recognized the important contributions of Rosalind Franklin, whose X-ray images, like "photograph 51", were key to understanding DNA's double helix shape.
Later Years at the Royal Institution
In 1953, the Braggs moved to London, where Lawrence became the Resident Professor at the Royal Institution. This was the same position his father had held. He worked hard to rebuild the Institution, getting support from companies and holding popular lectures.
He also continued his research, focusing on the structures of enzymes. In 1965, his team at the Royal Institution, led by D. C. Phillips, successfully figured out the complete structure of the enzyme lysozyme. This was another major achievement in understanding biological molecules.
Bragg retired in 1966, becoming Professor Emeritus. His work helped make X-ray analysis a vital tool in science, leading to many more discoveries and Nobel Prizes. He also started research into using electron microscopes to image single frozen molecules, which led to cryo-electron microscopy.
Personal Life
In 1921, Lawrence Bragg married Alice Hopkinson. They had four children: Stephen Lawrence, David William, Margaret Alice, and Patience Mary. Alice was also very active in public life and even served as the Mayor of Cambridge from 1945-46.
Bragg enjoyed drawing, painting, reading, and especially gardening. He even worked as a part-time gardener without his employer knowing who he was! He died in 1971 near his home in Waldringfield, England, and was buried in Trinity College, Cambridge.
Honours and Awards
Lawrence Bragg received many honors throughout his life. He was elected a Fellow of the Royal Society in 1921, which is a very high honor for a scientist. He was knighted by King George VI in 1941.
He also received several prestigious medals from the Royal Society, including the Copley Medal and the Royal Medal. In 1967, he was appointed a Companion of Honour by Queen Elizabeth II.
To remember his amazing contributions to science, the Institute of Physics has awarded the Lawrence Bragg Medal and Prize since 1967. The Australian Institute of Physics also awards the Bragg Gold Medal for the best PhD thesis in physics by a student at an Australian university.
Some of his major awards include:
- Nobel Prize in Physics (1915)
- Matteucci Medal (1915)
- Hughes Medal (1931)
- Royal Medal (1946)
- Guthrie Lecture (1952)
- Copley Medal (1966)
See also
In Spanish: William Lawrence Bragg para niños
- List of Nobel laureates in Physics
- Tactical artillery terms from World War I
- Tube Alloys
