Øyvind Grøn (born 11 March 1944) is a Norwegian physicist.

Biography

Grøn was born in

Oslo Oslo ( , , or ; sma, Oslove) is the capital and most populous city of Norway. It constitutes both a county and a municipality. The municipality of Oslo had a population of in 2022, while the city's greater urban area had a population ...

, and is a

twin Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two em ...

. He took the cand. real. degree at the

University of Oslo The University of Oslo ( no, Universitetet i Oslo; la, Universitas Osloensis) is a public research university located in Oslo, Norway. It is the highest ranked and oldest university in Norway. It is consistently ranked among the top universit ...

in 1973, majoring in

meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...

. He followed up with the PhD degree in 1990 with a thesis on repulsive gravitation. He started his academic career as a

research assistant A research assistant (RA) is a researcher employed, often on a temporary contract, by a university, a research institute or a privately held organization, for the purpose of assisting in academic or private research. Research assistants are not in ...

at the University of Oslo, and has also been a lecturer there. He was appointed as a professor at

Oslo University College Oslo University College ( no, Høgskolen i Oslo; HiO) was the largest state university college in Norway from 1994 to 2011, with more than 18,000 students and approximately 1800 employees.

in 1994, having been an associate professor since 1985. He has also been professor II at the University of Oslo since 1994.

Scientific contributions

Rotating reference frames

Grøn has conducted research within the areas of general relativity, cosmology and classical electromagnetism. He has thrown new light on themes like the

twin paradox In physics, the twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. Thi ...

, the physics in a rotating reference system (

Ehrenfest paradox The Ehrenfest paradox concerns the rotation of a "rigid" disc in the theory of relativity. In its original 1909 formulation as presented by Paul Ehrenfest in relation to the concept of Born rigidity within special relativity, it discusses an idea ...

) and repulsive gravitation associated with vacuum energy. Together with Erik Eriksen at the University of Oslo he has also studied properties of the electromagnetic field produced by accelerated electric charges. They have in particular shown how gravitation impacts such fields. Grøn has also found new solutions to equations in Einstein's theory of gravity that describe time space where one can travel backwards in time. In several studies Grøn has focused on relativistic models of the universe. He has, among other things, shown that it is possible to interpret observations from cosmos so that the concept of dark energy is unnecessary.

Repulsive gravitation

The relationship between gravitation and time and between gravitation and entropy are also themes where Grøn has contributed several journal articles. He has also contributed to the Kaluza-Klein theory that represents a geometric and unified theory of electromagnetism and gravitation. According to this theory the world is five-dimensional with a compact spatial dimension so small that it is not observable directly. He has shown that the electric field around a charged particle is the projection of the relativistic inertial dragging field caused by the particle's movement around the fifth dimension in our four-dimensional spacetime.

Radiation from accelerated charges

Grøn (together with Matthew Aadne) have found solutions to the field equations without a cosmological constant for empty space in the theory of gravitation developed by John Nash. They correspond to the solutions of the field equations with a cosmological constant in the gravitational theory developed by Einstein. Since the physical interpretation of the cosmological constant is that it represents the density of dark energy, the solutions indicate that dark energy may be superfluous according to the Nash-theory. Grøn has written three books on the theory of relativity. Grøn is a member of the

editorial board The editorial board is a group of experts, usually at a publication, who dictate the tone and direction the publication's editorial policy will take. Mass media At a newspaper, the editorial board usually consists of the editorial page editor, ...

of '' ''Universe''''. He is also known for his

popular Popularity or social status is the quality of being well liked, admired or well known to a particular group. Popular may also refer to: In sociology * Popular culture * Popular fiction * Popular music * Popular science * Populace, the total ...

contributions, through the Norwegian Broadcasting Corporation, in popular articles and lectures, in books as well as the encyclopedias '' Store norske leksikon'' and ''

Norsk biografisk leksikon is the largest Norwegian biographical encyclopedia. The first edition (NBL1) was issued between 1921 and 1983, including 19 volumes and 5,100 articles. It was published by Aschehoug with economic support from the state. bought the rights to ...

''.

Bibliography

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References

{{DEFAULTSORT:Gron, Oyvind Norwegian physicists University of Oslo alumni Academic staff of Oslo University College Scientists from Oslo Norwegian twins 1944 births Living people Royal Norwegian Society of Sciences and Letters