Inge Lehmann facts for kids
Quick facts for kids
Inge Lehmann
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Lehmann in 1932
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| Born | 13 May 1888 Copenhagen, Denmark
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| Died | 21 February 1993 (aged 104) Copenhagen, Denmark
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| Resting place | Hørsholm Cemetery |
| Alma mater | University of Copenhagen, University of Cambridge |
| Awards | William Bowie Medal (1971) |
| Scientific career | |
| Fields | Seismology, geophysics |
| Institutions | Geodetical Institute of Denmark |
Inge Lehmann ForMemRS (13 May 1888 – 21 February 1993) was a brilliant Danish scientist. She studied earthquakes and the Earth's structure. In 1936, she made an amazing discovery: the Earth has a solid inner core surrounded by a liquid outer core.
Before her work, scientists thought the Earth's core was just one big melted ball. But their measurements of seismic waves from earthquakes didn't quite fit this idea. Inge carefully studied these earthquake waves. She realized that a solid inner core inside a liquid outer core would explain the measurements perfectly. Other scientists tested her idea and soon agreed with her. Inge Lehmann was also one of the longest-living scientists, reaching over 104 years old!
Contents
Early Life and Education
Inge Lehmann was born and grew up in Østerbro, a part of Copenhagen, Denmark. She was a very shy child, and this shyness stayed with her throughout her life. Her mother, Ida Sophie Tørsleff, was a housewife. Her father, Alfred Georg Ludvik Lehmann, was an experimental psychologist.
School Days and Influences
Inge went to Fællesskolen, a special high school. This school was ahead of its time because it treated girls and boys equally. They studied the same subjects and did the same activities. Hanna Adler, the aunt of famous physicist Niels Bohr, was the head of this school. Inge said that her father and Hanna Adler were the most important people in shaping her mind.
University Studies and Early Career
At 18, Inge passed her entrance exam for Copenhagen University with top marks. In 1907, she began studying mathematics, chemistry, and physics at the University of Copenhagen and University of Cambridge. Her studies were sometimes interrupted because of poor health.
She continued studying mathematics in Cambridge from 1910 to 1911 at Newnham College. In 1911, she returned to Denmark feeling tired from her studies and took a break. For a few years, she worked in an office that dealt with statistics, where she became very good with numbers. She went back to Copenhagen University in 1918. In just two years, she finished her degree in physical science and mathematics, graduating in 1920. When she returned to Denmark in 1923, she became an assistant to J.F. Steffensen, a professor of statistics at Copenhagen University.
Inge had a younger sister named Harriet, who became a movie writer. Harriet had a family and children, but Inge lived by herself her whole adult life.
Career and Discoveries
Inge Lehmann's career in seismology began in 1925. She became an assistant to Niels Erik Nørlund, a scientist who studied the Earth's shape and gravity. Inge worked with three other assistants who had never even seen a seismograph before. A seismograph is a tool that records ground motions caused by earthquakes.
Setting Up Observatories
Her first big task was to set up earthquake observatories in Denmark and Greenland. At the same time, she taught herself about seismology. She traveled for three months to learn from top experts like Beno Gutenberg. Gutenberg had already figured out the distance to the boundary between the Earth's core and mantle very accurately.
Leading Seismology in Denmark
Based on her studies, Inge earned a master's degree in geodesy in 1928. She then became the state geodesist and head of the seismology department at the Geodetical Institute of Denmark. This institute was led by Nørlund. Inge worked to improve how earthquake measurements from observatories across Europe were collected and analyzed. These improvements were key to her later amazing discoveries.
Discovering the Earth's Inner Core
In 1936, Inge published a very important paper called P'. In this paper, she was the first to explain strange earthquake wave signals. These signals, called P waves, appeared in an area where they shouldn't have been, according to what scientists then believed about the Earth's core. Inge realized these waves were reflecting off a solid inner core. She used data from a strong earthquake in 1929 to support her idea.
Other leading seismologists, like Beno Gutenberg, Charles Richter, and Harold Jeffreys, soon accepted her explanation. However, it took until 1971 for computer calculations to fully prove her interpretation was correct. Inge's work was made harder during the German occupation of Denmark in World War II. She served as the Chair of the Danish Geophysical Society in 1940 and 1944.
Later Work and the Lehmann Discontinuity
In 1952, Inge was considered for a professorship at Copenhagen University, but she was not chosen. In 1953, she retired from her job at the Geodetic Institute. She then moved to the United States for several years. There, she worked with other scientists like Maurice Ewing and Frank Press. They studied the Earth's crust and the upper mantle.
During this time, she found another seismic discontinuity. This is a place deep inside the Earth where the speed of earthquake waves suddenly changes. This change happens at depths between 190 and 250 kilometers. This important boundary was named the Lehmann discontinuity in her honor. Another geophysicist, Francis Birch, said that Inge discovered this through her careful study of earthquake records. He called her a "master of a black art" that computers probably couldn't fully replace.
Awards and Legacy
Inge Lehmann received many awards for her amazing scientific work. These include the Gordon Wood Award (1960) and the Emil Wiechert Medal (1964). She also received the Gold Medal of the Danish Royal Society of Science and Letters (1965). She was elected as a Fellow of the Royal Society in 1969. In 1971, she was the first woman to receive the William Bowie Medal. She also received the Medal of the Seismological Society of America in 1977.
She was given honorary doctorates from Columbia University in 1964 and from the University of Copenhagen in 1968. She also became an honorary member of many scientific groups.
Honors and Recognition
An asteroid, 5632 Ingelehmann, was named after her. In 2015, which was 100 years after women gained the right to vote in Denmark, a new beetle species was named in her honor: Globicornis (Hadrotoma) ingelehmannae. This recognized her struggle in the male-dominated science world of her time.
Because of her important contributions to geology, the American Geophysical Union created the annual Inge Lehmann Medal in 1997. This medal honors scientists who make "outstanding contributions to understanding the Earth's mantle and core."
In 2014, Christiane Rousseau received the George Pólya Award for her article "How Inge Lehmann Discovered the Inner Core of the Earth." In 2015, on her 127th birthday, Google dedicated its worldwide Google Doodle to her. A new memorial dedicated to Inge Lehmann was placed in Copenhagen in 2017. The artist Elisabeth Toubro designed this monument.
Key Publications
- Lehmann, Inge (1936). "P'". Publications du Bureau Central Séismologique International A14 (3): 87–115.
See also
- Richard Dixon Oldham
- List of geophysicists
- Timeline of women in science
