# Tjalling Koopmans

> Dutch American economist (1910–1985)

**Wikidata**: [Q110968](https://www.wikidata.org/wiki/Q110968)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Tjalling_Koopmans)  
**Source**: https://4ort.xyz/entity/tjalling-koopmans

## Summary
Tjalling Charles Koopmans (1910–1985) was a Dutch American economist, mathematician, and physicist who was awarded the Prize in Economic Sciences in Memory of Alfred Nobel. He is best known for his foundational contributions to the field of economics, particularly his work on optimum resource allocation, and for formulating "Koopmans' theorem" in quantum mechanics.

## Biography
- Born: August 28, 1910
- Died: February 26, 1985
- Nationality: Dutch American (Kingdom of the Netherlands, United States)
- Education: Utrecht University, University of Amsterdam, Leiden University, University of Oslo
- Known for: Foundational work in economics, mathematical optimization, and Koopmans' theorem
- Employer(s): Princeton University, Yale University, University of Chicago, League of Nations
- Field(s): Economics, Mathematics, Physics
- Influenced by: George Bernard Dantzig

## Contributions
Koopmans' primary contribution to economics lies in his pioneering work in optimization and resource allocation. He was heavily involved in the development of linear programming and economic theory, drawing on the work of George Bernard Dantzig, the American mathematician who developed the simplex algorithm. Koopmans applied these mathematical frameworks to economic problems, helping to formalize the field of econometrics. Beyond economics, he also formulated "Koopmans' theorem," a principle in quantum mechanics stating that in closed-shell Hartree–Fock theory, the first ionization energy of a molecular system equals the negative of the orbital energy of the highest occupied molecular orbital.

## FAQs
**What was Tjalling Koopmans' most famous achievement?**
Koopmans was awarded the Prize in Economic Sciences in Memory of Alfred Nobel for his groundbreaking work in the theory of optimum resource allocation. Additionally, he is the namesake of Koopmans' theorem in quantum mechanics.

**Where did Tjalling Koopmans work and study?**
Throughout his career, Koopmans was affiliated with Princeton University, Yale University, and the University of Chicago, and he worked for the League of Nations. He received his education at Utrecht University, the University of Amsterdam, Leiden University, and the University of Oslo.

**Who influenced Tjalling Koopmans' work?**
His work in mathematical optimization and linear programming was notably influenced by the American mathematician George Bernard Dantzig, the pioneer of the simplex algorithm.

## Why They Matter
Tjalling Koopmans significantly shaped the intersection of economics, mathematics, and physics. By bridging these disciplines, he provided rigorous mathematical frameworks for solving complex economic problems regarding the optimal allocation of resources. His integration of techniques from operations research and linear programming transformed theoretical economics into a more quantifiable and applied science. Furthermore, his cross-disciplinary reach is evident in physics through Koopmans' theorem, demonstrating his profound versatility. Without his contributions, the modern field of econometrics and the mathematical tools used for economic modeling and logistical optimization would lack critical structural foundations.

## Notable For
- Receiving the **Prize in Economic Sciences in Memory of Alfred Nobel**.
- Formulating **Koopmans' theorem**, a significant principle in quantum mechanics related to Hartree–Fock theory and ionization energy.
- Holding memberships in prestigious academic societies, including the **American Academy of Arts and Sciences**, the **National Academy of Sciences**, the **Institute of Mathematical Statistics**, and the **Econometric Society**.
- His academic tenure at top-tier Ivy League and research institutions, including **Princeton University**, **Yale University**, and the **University of Chicago**.
- His foundational role in applying **linear programming** and optimization to economic theory.

## Body

### Early Life and Background
Tjalling Charles Koopmans was born on August 28, 1910, and passed away on February 26, 1985. He held dual nationality as a Dutch American citizen, connected to both the Kingdom of the Netherlands and the United States. 

### Academic Training
Koopmans had an extensive educational background across multiple prestigious European institutions. He studied at Utrecht University, the University of Amsterdam, Leiden University, and the University of Oslo. His diverse academic training laid the groundwork for his future interdisciplinary work spanning economics, mathematics, and physics.

### Professional Affiliations
During his distinguished career, Koopmans was affiliated with several major academic and governmental institutions. He held positions at Princeton University, Yale University, and the University of Chicago. He also dedicated a period of his career to working at the League of Nations. 

### Academic Societies and Recognition
Koopmans was a highly recognized member of the global academic community. He was granted membership in several elite organizations, such as:
- The American Academy of Arts and Sciences
- The National Academy of Sciences
- The Institute of Mathematical Statistics
- The Econometric Society

His crowning professional achievement in economics was being awarded the prestigious Prize in Economic Sciences in Memory of Alfred Nobel.

### Scientific and Economic Contributions
Primarily regarded as an economist, Koopmans also possessed extensive expertise as a mathematician and physicist. His primary notable work involves the application of mathematical optimization to economic theory, heavily influenced by the groundbreaking linear programming work of George Bernard Dantzig. 

Uniquely, his contributions were not limited to the social sciences. In the realm of physics, he formulated "Koopmans' theorem." This theorem dictates that within closed-shell Hartree–Fock theory, the first ionization energy of a molecular system is equal to the negative of the orbital energy of the highest occupied molecular orbital.

## References

1. MacTutor History of Mathematics archive
2. Integrated Authority File
3. BnF authorities
4. [The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel 1975. nobelprize.org](https://www.nobelprize.org/prizes/economic-sciences/1975/summary/)
5. [Source](https://www.econometricsociety.org/society/organization-and-governance/fellows/memoriam)
6. Scientific Legacy Database
7. Mathematics Genealogy Project
8. International Standard Name Identifier
9. Open Library
10. Virtual International Authority File
11. [Source](http://hdl.handle.net/10079/fa/mssa.ms.1439)
12. Tjalling Charles Koopmans. Biografisch Portaal
13. SNAC
14. Brockhaus Enzyklopädie
15. Munzinger Personen
16. Gran Enciclopèdia Catalana
17. Freebase Data Dumps. 2013
18. LIBRIS. 2012