Stjepan Mohorovičić (August 20, 1890 – February 13, 1980) was a

Croatia Croatia, officially the Republic of Croatia, is a country in Central Europe, Central and Southeast Europe, on the coast of the Adriatic Sea. It borders Slovenia to the northwest, Hungary to the northeast, Serbia to the east, Bosnia and Herze ...

n physicist, geophysicist and

meteorologist A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmosphere of Earth, atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists ...

Biography

Mohorovičić was born in the town of Bakar. His father was the world-famous

geophysicist Geophysics () is a subject of natural science concerned with the physical processes and properties of Earth and its surrounding space environment, and the use of quantitative methods for their analysis. Geophysicists conduct investigations acros ...

Andrija Mohorovičić. He studied

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

and

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

at the

University of Zagreb The University of Zagreb (, ) is a public university, public research university in Zagreb, Croatia. It is the largest Croatian university and one of the oldest continuously operating universities in Europe. The University of Zagreb and the Unive ...

where among others his professors were Vinko Dvořák and Andrija Mohorovičić, and later he studied at

Göttingen Göttingen (, ; ; ) is a college town, university city in Lower Saxony, central Germany, the Capital (political), capital of Göttingen (district), the eponymous district. The River Leine runs through it. According to the 2022 German census, t ...

where some of his professors were

Arnold Sommerfeld Arnold Johannes Wilhelm Sommerfeld (; 5 December 1868 – 26 April 1951) was a German Theoretical physics, theoretical physicist who pioneered developments in Atomic physics, atomic and Quantum mechanics, quantum physics, and also educated and ...

Woldemar Voigt Woldemar Voigt (; 2 September 1850 – 13 December 1919) was a German mathematician and physicist. Biography Voigt was born in Leipzig, and died in Göttingen. He was a student of Franz Ernst Neumann. Voigt taught at the Georg August Universi ...

and

David Hilbert David Hilbert (; ; 23 January 1862 – 14 February 1943) was a German mathematician and philosopher of mathematics and one of the most influential mathematicians of his time. Hilbert discovered and developed a broad range of fundamental idea ...

. Later on he received a doctorate degree from the University of Zagreb. Mohorovičić was an opponent of Einstein's theory of relativity. Because of his longtime opposition and criticisms of

theory of relativity The theory of relativity usually encompasses two interrelated physics theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively. Special relativity applies to all physical ph ...

he remained a high school professor his whole life. His work went largely ignored, especially in

. He died in

Zagreb Zagreb ( ) is the capital (political), capital and List of cities and towns in Croatia#List of cities and towns, largest city of Croatia. It is in the Northern Croatia, north of the country, along the Sava river, at the southern slopes of the ...

Scientific work

His scientific interests included

seismology Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes (or generally, quakes) and the generation and propagation of elastic ...

meteorology Meteorology is the scientific study of the Earth's atmosphere and short-term atmospheric phenomena (i.e. weather), with a focus on weather forecasting. It has applications in the military, aviation, energy production, transport, agricultur ...

astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the ...

and

theoretical physics Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain, and predict List of natural phenomena, natural phenomena. This is in contrast to experimental p ...

. He began his career in seismology with his father. In 1913 he developed a new method for locating the

hypocenter A hypocenter or hypocentre (), also called ground zero or surface zero, is the point on the Earth's surface directly below a nuclear explosion, meteor air burst, or other mid-air explosion. In seismology, the hypocenter of an earthquake is its ...

of an

earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

and gave an independent verification of discontinuity theory put forward by his father. In 1916 he published an idea of the existence of smaller discontinuities in

Earth's crust Earth's crust is its thick outer shell of rock, referring to less than one percent of the planet's radius and volume. It is the top component of the lithosphere, a solidified division of Earth's layers that includes the crust and the upper ...

and mantle. He put forward his own theory about the composition and the formation of the Moon, explosive formation of

lunar craters Lunar craters are impact craters on Earth's Moon. The Moon's surface has many craters, all of which were formed by impacts. The International Astronomical Union currently recognizes 9,137 craters, of which 1,675 have been dated. History The wo ...

and predicted the existence of Moho layer on the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

. The existence of Moho layer on the Moon was confirmed in 1969 by seismic measurements done by Apollo 11 crew. Mohorovičić is often called "the father of

positronium Positronium (Ps) is a system consisting of an electron and its antimatter, anti-particle, a positron, bound together into an exotic atom, specifically an onium. Unlike hydrogen, the system has no protons. The system is unstable: the two part ...

" because his most significant work is the prediction of the existence of positronium. Positronium is the

bound state A bound state is a composite of two or more fundamental building blocks, such as particles, atoms, or bodies, that behaves as a single object and in which energy is required to split them. In quantum physics, a bound state is a quantum state of a ...

of an

electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...

and a

positron The positron or antielectron is the particle with an electric charge of +1''elementary charge, e'', a Spin (physics), spin of 1/2 (the same as the electron), and the same Electron rest mass, mass as an electron. It is the antiparticle (antimatt ...

and therefore the lightest

atom Atoms are the basic particles of the chemical elements. An atom consists of a atomic nucleus, nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished fr ...

. It was experimentally discovered in 1951 by Martin Deutsch and became known as positronium. Mohorovičić in his paper also calculated spectra of positronium and predicted the existence of positronium in

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

s because of which he suggested the identification of possible

spectral line A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission (electromagnetic radiation), emission or absorption (electromagnetic radiation), absorption of light in a narrow frequency ...

s of positronium in spectra of stars. He was searching for spectra of positronium in the sky, but unsuccessfully. Positronium lines were first identified in lab in 1975 by Canter et al. and in outer space in spectra of

Crab Nebula The Crab Nebula (catalogue designations M1, NGC 1952, Taurus A) is a supernova remnant and pulsar wind nebula in the constellation of Taurus (constellation), Taurus. The common name comes from a drawing that somewhat resembled a crab with arm ...

in 1984 by J. E. McClintock.

References

External links

* {{DEFAULTSORT:Mohorovicic, Stjepan 1980 deaths 1890 births Croatian physicists Croatian scientists Relativity critics

Biography

Scientific work

See also

References

External links