Anders Lindstedt
Encyclopedia
Anders Lindstedt was a Swedish mathematician
, astronomer, and actuarial scientist
, known for the Lindstedt-Poincaré method.
. He obtained a PhD from the University of Lund aged 32 and was subsequently appointed as a lecturer in astronomy. He later went on to a position at the University of Dorpat (then belonging to Russia, now University of Tartu
in Estonia) where he worked for around seven years on theoretical astronomy. He combined practical astronomy with an interest in theory, developing especially an interest in the three body problem This work was to influence Poincaré whose work on the three-body problem led to the discovery that there can be orbits which are nonperiodic, and yet not forever increasing nor approaching a fixed point, the beginning of what we now know as 'chaos theory
'.
His papers on celestial mechanics
written during that period include a technique for uniformly approximating periodic solutions to ordinary differential equations when regular perturbation approaches fail. This was later developed by Henri Poincaré
and is known today as the Lindstedt–Poincaré method.
Lindstedt returned to Sweden in 1886 to take a post as professor at the Royal Institute of Technology
in Stockholm
. During the period occupying this position, until 1909, he developed an interest in actuarial science
. He made contributions to the theory of pension funds and worked as a member of government committees responsible for insurance law
and social insurance
. He became a corresponding member of the Institute of Actuaries
in London. He was for a time Kings Inspector of insurance companies.
In 1909 he resigned his professorial position to work full time on insurance
. From 1909 to 1916 Lindstedt was also a Justice of the Supreme Administrative Court of Sweden
. In 1912 Lindstedt constructed a life table
for annuities
using data from Swedish population experience and for each age was able to extrapolate the sequence of annual probability
of death, namely the mortality profile. Probably, this work constitutes the earliest projection of age-specific functions. He directed the actuarial work which underpinned the state old age an invalidity pensions in Sweden introduced in 1913 as part of the National Pension Act (see Swedish welfare).
Even after his retirement aged 70 he continued to take an active interest in actuarial activities both in Sweden and abroad, attending meetings of the Swedish Actuarial Society
until shortly before his death in 1939.
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
, astronomer, and actuarial scientist
Actuarial science
Actuarial science is the discipline that applies mathematical and statistical methods to assess risk in the insurance and finance industries. Actuaries are professionals who are qualified in this field through education and experience...
, known for the Lindstedt-Poincaré method.
Life and work
Lindstedt was born in a small village in the district of Sundborns, Dalecarlia a province in central SwedenSweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
. He obtained a PhD from the University of Lund aged 32 and was subsequently appointed as a lecturer in astronomy. He later went on to a position at the University of Dorpat (then belonging to Russia, now University of Tartu
University of Tartu
The University of Tartu is a classical university in the city of Tartu, Estonia. University of Tartu is the national university of Estonia; it is the biggest and highest-ranked university in Estonia...
in Estonia) where he worked for around seven years on theoretical astronomy. He combined practical astronomy with an interest in theory, developing especially an interest in the three body problem This work was to influence Poincaré whose work on the three-body problem led to the discovery that there can be orbits which are nonperiodic, and yet not forever increasing nor approaching a fixed point, the beginning of what we now know as 'chaos theory
Chaos theory
Chaos theory is a field of study in mathematics, with applications in several disciplines including physics, economics, biology, and philosophy. Chaos theory studies the behavior of dynamical systems that are highly sensitive to initial conditions, an effect which is popularly referred to as the...
'.
His papers on celestial mechanics
Celestial mechanics
Celestial mechanics is the branch of astronomy that deals with the motions of celestial objects. The field applies principles of physics, historically classical mechanics, to astronomical objects such as stars and planets to produce ephemeris data. Orbital mechanics is a subfield which focuses on...
written during that period include a technique for uniformly approximating periodic solutions to ordinary differential equations when regular perturbation approaches fail. This was later developed by Henri Poincaré
Henri Poincaré
Jules Henri Poincaré was a French mathematician, theoretical physicist, engineer, and a philosopher of science...
and is known today as the Lindstedt–Poincaré method.
Lindstedt returned to Sweden in 1886 to take a post as professor at the Royal Institute of Technology
Royal Institute of Technology
The Royal Institute of Technology is a university in Stockholm, Sweden. KTH was founded in 1827 as Sweden's first polytechnic and is one of Scandinavia's largest institutions of higher education in technology. KTH accounts for one-third of Sweden’s technical research and engineering education...
in Stockholm
Stockholm
Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...
. During the period occupying this position, until 1909, he developed an interest in actuarial science
Actuarial science
Actuarial science is the discipline that applies mathematical and statistical methods to assess risk in the insurance and finance industries. Actuaries are professionals who are qualified in this field through education and experience...
. He made contributions to the theory of pension funds and worked as a member of government committees responsible for insurance law
Insurance law
Insurance law is the name given to practices of law surrounding insurance, including insurance policies and claims. It can be broadly broken into three categories - regulation of the business of insurance; regulation of the content of insurance policies, especially with regard to consumer...
and social insurance
Social insurance
Social insurance is any government-sponsored program with the following four characteristics:* the benefits, eligibility requirements and other aspects of the program are defined by statute;...
. He became a corresponding member of the Institute of Actuaries
Institute of Actuaries
The Institute of Actuaries was one of the two professional which represented actuaries in the United Kingdom . The Institute was based in England, while the other body, the Faculty of Actuaries, was based in Scotland...
in London. He was for a time Kings Inspector of insurance companies.
In 1909 he resigned his professorial position to work full time on insurance
Insurance
In law and economics, insurance is a form of risk management primarily used to hedge against the risk of a contingent, uncertain loss. Insurance is defined as the equitable transfer of the risk of a loss, from one entity to another, in exchange for payment. An insurer is a company selling the...
. From 1909 to 1916 Lindstedt was also a Justice of the Supreme Administrative Court of Sweden
Supreme Administrative Court of Sweden
The Supreme Administrative Court of Sweden is the supreme court and the third and final tier for administrative court cases in Sweden, and is located in Stockholm...
. In 1912 Lindstedt constructed a life table
Life table
In actuarial science, a life table is a table which shows, for each age, what the probability is that a person of that age will die before his or her next birthday...
for annuities
Annuity (European financial arrangements)
An annuity can be defined as a financial contract which provides an income stream in return for an initial payment with specific parameters. It is the opposite of a settlement funding...
using data from Swedish population experience and for each age was able to extrapolate the sequence of annual probability
Probability
Probability is ordinarily used to describe an attitude of mind towards some proposition of whose truth we arenot certain. The proposition of interest is usually of the form "Will a specific event occur?" The attitude of mind is of the form "How certain are we that the event will occur?" The...
of death, namely the mortality profile. Probably, this work constitutes the earliest projection of age-specific functions. He directed the actuarial work which underpinned the state old age an invalidity pensions in Sweden introduced in 1913 as part of the National Pension Act (see Swedish welfare).
Even after his retirement aged 70 he continued to take an active interest in actuarial activities both in Sweden and abroad, attending meetings of the Swedish Actuarial Society
until shortly before his death in 1939.