George William Hill facts for kids
Quick facts for kids
George William Hill
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George William Hill
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| Born | March 3, 1838 New York City, U.S.
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| Died | April 16, 1914 (aged 76) West Nyack, New York, U.S.
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| Nationality | American |
| Alma mater | Rutgers University |
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| Scientific career | |
| Fields | Astronomy, mathematics |
| Institutions | Columbia University, United States Naval Observatory |
| Academic advisors | Theodore Strong |
| Influences | Charles-Eugène Delaunay, Peter Andreas Hansen |
| Influenced | Henri Poincaré, George Darwin |
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George William Hill (born March 3, 1838 – died April 16, 1914) was an American astronomer and mathematician. He worked mostly by himself, but he made very important discoveries in how planets and moons move (called celestial mechanics). He also helped develop the theory of ordinary differential equations, which are special math problems.
A famous French mathematician, Henri Poincaré, praised Hill's work in 1905. In 1909, Hill received the Copley Medal from the Royal Society for his amazing research in mathematical astronomy. Today, he is best known for the Hill differential equation, a key idea in math and physics.
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Early Life and Learning
George William Hill was born in New York City. His father, John William Hill, was a painter and engraver. When George was eight, his family moved to West Nyack.
After finishing high school, Hill went to Rutgers College. There, he became very interested in mathematics. His professor, Theodore Strong, was a big influence. Strong was friends with another important American mathematician, Nathaniel Bowditch.
Professor Strong encouraged Hill to read books by famous mathematicians. These included works on analysis by Sylvestre Lacroix and Adrien-Marie Legendre. He also studied books on mechanics and astronomy by Joseph-Louis Lagrange, Pierre-Simon Laplace, Siméon Denis Poisson, and Gustave de Pontécoulant.
Hill graduated from Rutgers College in 1859 with a Bachelor of Arts degree. That same year, he published his first science paper. It was about the shape of a drawbridge. Two years later, he won a prize for his work on the mathematical theory of the figure of the Earth.
In the early 1860s, Hill started studying the works of Charles-Eugène Delaunay and Peter Andreas Hansen. Their ideas about how the Moon moves (called lunar theory) inspired much of Hill's future research. In 1861, Hill began working for the United States Naval Observatory in Cambridge, Massachusetts.
Rutgers gave Hill a Master of Arts degree in 1862. Hill lived in Cambridge and later in Washington, D.C. for a while. However, he preferred to do his math work at his family farm in West Nyack. He moved back there permanently after 1892.
Amazing Work in Astronomy
Hill's most important work focused on the math of the three-body problem. This problem tries to figure out how three objects in space move when they pull on each other with gravity. Later, he also studied the four-body problem. He used these ideas to calculate the paths of the Moon around the Earth. He also calculated the paths of planets around the Sun.
Hill came up with a way to measure how much an astronomical body's gravity affects things around it. He called this the "zero-velocity surface". The area inside this surface is now known as the Hill sphere. It's the region around a body where it can capture other objects, like satellites.
In 1878, Hill found the first complete math solution for a tough problem. This problem was about the Moon's orbit around the Earth. It's called the apsidal precession of the Moon. Isaac Newton first brought up this problem in his famous book Principia Mathematica in 1687.
In this same work, Hill also introduced what is now called the "Hill differential equation". This equation describes how a special kind of vibrating system behaves. It was a very important step forward in a math field called Floquet theory.
How Hill Was Recognized
Hill's work caught the attention of scientists all over the world. In 1894, he was chosen to be the president of the American Mathematical Society. He served in this role for two years.
Hill also taught at Columbia University from 1898 to 1901. But he didn't have many students. He eventually decided to give back his salary and go back to working alone at his home in West Nyack. He preferred to work by himself rather than in a university setting.
The Collected Works of George William Hill were published between 1905 and 1907. The Carnegie Institution for Science put them out. The famous French mathematician and physicist Henri Poincaré wrote a 12-page introduction for the collection.
In his introduction, Poincaré said that Hill's 1878 article, "Researches in the lunar theory," contained "the beginning of most of the progress that [celestial mechanics] has made ever since." Poincaré also commented on Hill's choice to work alone, saying:
This reserve, I was going to say this savagery, has been a happy circumstance for science, because it has allowed him to complete his ingenious and patient researches.
George William Hill became a foreign member of the Royal Society of London in 1902. He also joined the Royal Society of Edinburgh in 1908. He became a member of science academies in Belgium (1909), Norway (1910), Sweden (1913), and the Netherlands (1914). He had poor health in his later years and died in West Nyack in 1914. He never married or had children.
Honors and Awards
George William Hill received many important awards and honors for his work:
- Gold Medal of the Royal Astronomical Society (1887)
- Damoiseau Prize from the Institut de France (1898)
- Copley Medal of the Royal Society of London (1909)
- Bruce Medal of the Astronomical Society of the Pacific (1909)
He also has some things named after him:
- Hill crater on the Moon
- Asteroid 1642 Hill
- The Hill Center for the Mathematical Sciences at Rutgers University's Busch Campus
