Janez Strnad (March 4, 1934 – November 28, 2015) was a Slovene

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

and popularizer of

natural science Natural science or empirical science is one of the branches of science concerned with the description, understanding and prediction of natural phenomena, based on empirical evidence from observation and experimentation. Mechanisms such as peer ...

Life and work

Strnad was born in

Ljubljana {{Infobox settlement , name = Ljubljana , official_name = , settlement_type = Capital city , image_skyline = {{multiple image , border = infobox , perrow = 1/2/2/1 , total_widt ...

Kingdom of Yugoslavia The Kingdom of Yugoslavia was a country in Southeast Europe, Southeast and Central Europe that existed from 1918 until 1941. From 1918 to 1929, it was officially called the Kingdom of Serbs, Croats, and Slovenes, but the term "Yugoslavia" () h ...

(now

Slovenia Slovenia, officially the Republic of Slovenia, is a country in Central Europe. It borders Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the south and southeast, and a short (46.6 km) coastline within the Adriati ...

). He received a degree at the University of Ljubljana in

technical physics Engineering physics (EP), sometimes engineering science, is the field of study combining pure science disciplines (such as physics, mathematics, chemistry or biology) and engineering disciplines (computer, nuclear, electrical, aerospace, medica ...

in 1957, and got his Ph.D. in 1963. His main research work was carried out at the Jožef Stefan Institute. He taught for many years beginning in 1961 at the

University of Ljubljana The University of Ljubljana (, , ), abbreviated UL, is the oldest and largest university in Slovenia. It has approximately 38,000 enrolled students. The university has 23 faculties and three art academies with approximately 4,000 teaching and re ...

, Faculty for natural science and

technology Technology is the application of Conceptual model, conceptual knowledge to achieve practical goals, especially in a reproducible way. The word ''technology'' can also mean the products resulting from such efforts, including both tangible too ...

on the Department of physics introductory courses and topics from

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 ...

. In 1974 he became a full professor. In 1990 he wrote a book about

fundamental particle In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. The Standard Model presently recognizes seventeen distinct particles—twelve fermions and five bosons. As a con ...

s physics entitled ''Iz take so snovi kot sanje'' (''We are such stuff as

dream A dream is a succession of images, ideas, emotions, and sensation (psychology), sensations that usually occur involuntarily in the mind during certain stages of sleep. Humans spend about two hours dreaming per night, and each dream lasts around ...

s are made of''). With his short and long articles he had deepened the knowledge about Stefan's

scientific Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...

work. His thick booklet in the series of monographs, ''Zbirka Sigma'' (the Sigma Collection), entitled ''Kvantna fizika'' (''

Quantum Physics Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is ...

''), (DZS, Ljubljana 1974) contains a definition and introduction to the understanding of

Heisenberg Werner Karl Heisenberg (; ; 5 December 1901 – 1 February 1976) was a German theoretical physicist, one of the main pioneers of the theory of quantum mechanics and a principal scientist in the German nuclear program during World War II. He pub ...

uncertainty principle The uncertainty principle, also known as Heisenberg's indeterminacy principle, is a fundamental concept in quantum mechanics. It states that there is a limit to the precision with which certain pairs of physical properties, such as position a ...

for the graduate beginner. He wrote over 1000 works. Strnad's works also includes topics of physics which are not exactly related at first glance to it, for instance as in this his article ''Znanost in politika v vinjetah'' (''Science and politics in vignettes'')].Znanost in politika v vinjetah by Dr. Janez Strnad
/ref>

Selected works

University textbooks

# Janez Strnad, ''Atlas klasične in moderne fizike'' (''Atlas of classical and modern physics''), translation and adaptation of Hans Breuer, ''dtv-Atlas zur Physik'', (Deutscher Taschenbuch Verlag, München 1987, 1988), DZS, Ljubljana 1993, pp 400, . # Janez Strnad, ''Fizika, 1. del, Mehanika, Toplota'' (''Physics, 1st part,

Mechanics Mechanics () is the area of physics concerned with the relationships between force, matter, and motion among Physical object, physical objects. Forces applied to objects may result in Displacement (vector), displacements, which are changes of ...

Heat In thermodynamics, heat is energy in transfer between a thermodynamic system and its surroundings by such mechanisms as thermal conduction, electromagnetic radiation, and friction, which are microscopic in nature, involving sub-atomic, ato ...

''), (DZS, Ljubljana 1977, pp 1 – 284. # Janez Strnad, ''Fizika, 2. del, Elektrika, Optika'' (''Physics, 2nd part,

Electricity Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

Optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes t ...

''), (DZS, Ljubljana 1978, pp 285 – 564). # Janez Strnad, ''Fizika, 3. del, Posebna teorija relativnosti, Atomi'' (''Physics, 3rd part,

Special Theory of relativity In physics, the special theory of relativity, or special relativity for short, is a scientific theory of the relationship between space and time. In Albert Einstein's 1905 paper, "On the Electrodynamics of Moving Bodies", the theory is presen ...

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 ...

s''), (DZS, Ljubljana 1980, pp 320). # Janez Strnad, ''Fizika, 4. del, Molekule, kristali, jedra, delci'' (''Physics, 4th part,

Molecule A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...

Crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

s, Nuclei, Particles''), (DZS, Ljubljana 1982, pp 283). # Janez Strnad, Mladen Gros, Marjan Hribar, Alojz Kodre, ''Naloge iz fizike'' (''Exercises from Physics''), (DMFA SRS, Ljubljana 1981, pp 108).

Selected chapters from physics and postgraduate seminars

# Janez Strnad, ''Fazna, skupinska, signalna hitrost'' (''Phase, Group, Signal

Velocity Velocity is a measurement of speed in a certain direction of motion. It is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of physical objects. Velocity is a vector (geometry), vector Physical q ...

''), (DMFA SRS, Ljubljana 1975, pp 31). # Janez Strnad, ''Poskusi v posebni in splošni teoriji relativnosti'' (''Experiments in Special and

General Theory of Relativity General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physi ...

''), (DMFA SRS, Ljubljana 1977, pp 44). #Janez Strnad, ''Na pot v kvantno elektrodinamiko'' (''On the way to the

Quantum Electrodynamics In particle physics, quantum electrodynamics (QED) is the Theory of relativity, relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quant ...

''), (DMFA SRS, Ljubljana 1986, pp 176). #Janez Strnad, ''Na pot k Schwarzschildu'' (''On the way to Schwarzschild''), (DMFA S, Ljubljana 1991, pp 52). #Janez Strnad, ''Homogeno gravitacijsko polje: med posebno in splošno teorijo relativnosti'' (''Homogeneous Gravitational Field: Between Special and General Theory of relativity''), (DMFA S, Ljubljana 1994, pp 44). #Janez Strnad, ''Začetki kvantne statistične mehanike'' (''The Beginnings of Quantum

Statistical Mechanics In physics, statistical mechanics is a mathematical framework that applies statistical methods and probability theory to large assemblies of microscopic entities. Sometimes called statistical physics or statistical thermodynamics, its applicati ...

''), (DMFA S, Ljubljana 1997, pp 31). #Janez Strnad, ''Odkritje razcepa'' (''Discovery of the split''), (DMFA S, Ljubljana 2000, pp 39).

Books

# Janez Strnad, ''Jožef Stefan, Ob stopetdesetletnici rojstva'' (''Jožef Stefan, By his 150th anniversary of birth''), (DMFA SRS, Ljubljana 1985). #Janez Strnad, ''Prapok Prasnov požene v dir'' (''Primordial

Bang Bang, bang!, or bangs may refer to: Products * M1922 Bang rifle, a US semi-automatic rifle designed by Søren Hansen Bang * Bang, a model car brand * Bang (beverage), an energy drink Geography * Bang, Central African Republic * Bang, Lores ...

drives Primordial Substance into a Gallop''), (DZS, Ljubljana 1988, pp 81). # Janez Strnad, ''Zgodbe iz fizike'' (''Stories from Physics''), (Slovenska matica, Ljubljana 1990). # Janez Strnad, ''Fiziki 1'' (''Physicists 1''), (Mihelač in Nešović, Ljubljana 1995, pp 159). # Janez Strnad, ''Razvoj fizike'' (''The Development of Physics''), (DZS Ljubljana 1996, pp 400). # Janez Strnad, ''Fiziki 2'' (''Physicists 2''), (Modrijan, Ljubljana 1999, pp 199). # Janez Strnad, ''Fiziki 3'' (''Physicists 3''), (Modrijan, Ljubljana 2000, pp 227). # Janez Strnad, ''Svet merjenj: o razvoju fizike in merjenju osnovnih fizikalnih količin'' (''The World of Measurements: About the Development of Physics and Measuring of Fundamental

Physical Quantities A physical quantity (or simply quantity) is a property of a material or system that can be quantified by measurement. A physical quantity can be expressed as a ''value'', which is the algebraic multiplication of a '' numerical value'' and a '' ...

''), (DZS, Ljubljana 2001, pp 139). #Janez Strnad, Sto let fizike: od 1900 do 2000 (''A Hundred Years of Physics: from 1900 to 2000''), (DMFA S, Ljubljana 2001, pp 233).

Scientific articles

# Janez Strnad, ''Sto let Stefanovega zakona'' (''Hundred years of Stefan's law''), (Obzornik mat, fiz. 26 (1979) 3). # Janez Strnad, A. Vengar, ''Stefanova meritev toplotne prevodnosti zraka'' (''Stefan's measurements of the

thermal conductivity The thermal conductivity of a material is a measure of its ability to heat conduction, conduct heat. It is commonly denoted by k, \lambda, or \kappa and is measured in W·m−1·K−1. Heat transfer occurs at a lower rate in materials of low ...

air An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

''), (European Journal of Physics, 1984). # Janez Strnad, ''Kako je Jožef Stefan odkril zakon o sevanju'' (''How Jožef Stefan discovered the law of

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes: * ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...

''), (Zbornik za zgodovino naravoslovja in tehnike 8, Ljubljana 1985). # Janez Strnad, ''Stefanov tok'' (''Stefan's current''), (Obzornik mat, fiz. 32 (1985). # Janez Strnad, ''Stefanova naloga'' (''Stefan's task''), (Obzornik mat, fiz. 34 (1987). # Janez Strnad, ''Stefanove elektodinamične enačbe'' (''Stefan's equations of electrodynamics''), (European Journal of Physics, 1989). # Janez Strnad, ''Ernst Mach kot fizik'' (''Ernst Mach as physicist''), (Zbornik za zgodovino naravoslovja in tehnike 10, Ljubljana 1989). # Janez Strnad, ''Dvigajoči se mehurčki'' (''Rising bubbles''), (Obzornik mat, fiz. 39 (1992) 4, pp 85 – 89). # Janez Strnad, ''Oslabitev Brownovega gibanja'' (''Squeezing

Brownian motion Brownian motion is the random motion of particles suspended in a medium (a liquid or a gas). The traditional mathematical formulation of Brownian motion is that of the Wiener process, which is often called Brownian motion, even in mathematical ...

''), (Obzornik mat, fiz. 39 (1992) 2, pp 49 – 54). # Janez Strnad, ''Opazovanje in teorija'' (''

Observation Observation in the natural sciences is an act or instance of noticing or perceiving and the acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the percep ...

and

theory A theory is a systematic and rational form of abstract thinking about a phenomenon, or the conclusions derived from such thinking. It involves contemplative and logical reasoning, often supported by processes such as observation, experimentation, ...

''), (Obzornik mat, fiz. 39 (1992) 5, pp 141 – 150). # Janez Strnad, ''J. Stefana 'Longitudinalna nihanja palic' '' (''J. Stefan's 'Longitudinal

oscillation Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

s of rods' ''), (Obzornik mat, fiz. 40 (1993) 1, pp 17 – 19). # Janez Strnad, ''Ali mora znati, kdor uči?'' (''Should he who teaches know?''), (Obzornik mat, fiz. 40 (1993) 1, pp 23 – 31). # Janez Strnad, ''Superprevodnost'' (''

Superconductivity Superconductivity is a set of physical properties observed in superconductors: materials where Electrical resistance and conductance, electrical resistance vanishes and Magnetic field, magnetic fields are expelled from the material. Unlike an ord ...

''), (Obzornik mat, fiz. 40 (1993) 4, pp 110 – 120). # Janez Strnad, ''Nenavadni interferenčni poskusi I. Interferenčni poskus s sevanjema v nasprotnih smereh'' (''Unusual

interference Interference is the act of interfering, invading, or poaching. Interference may also refer to: Communications * Interference (communication), anything which alters, modifies, or disrupts a message * Adjacent-channel interference, caused by extra ...

experiments I. Interference experiment with radiations in opposite directions''), (Obzornik mat, fiz. 40 (1993) 5, pp 135 – 136). # Janez Strnad, ''Supertekočnost'' (''

Superfluidity Superfluidity is the characteristic property of a fluid with zero viscosity which therefore flows without any loss of kinetic energy. When stirred, a superfluid forms vortices that continue to rotate indefinitely. Superfluidity occurs in two ...

''), (Obzornik mat, fiz. 40 (1993) 6, pp 183 – 191). # Janez Strnad, ''Fizika iz Karlsruheja: O novostih v poučevanju fizike'' (''The

Karlsruhe Karlsruhe ( ; ; ; South Franconian German, South Franconian: ''Kallsruh'') is the List of cities in Baden-Württemberg by population, third-largest city of the States of Germany, German state of Baden-Württemberg, after its capital Stuttgart a ...

physics course: On new approaches in physics teaching''), (Obzornik mat, fiz. 41 (1994) 4, pp 122 – 128). # Janez Strnad, ''Nenavadni interferenčni poskusi I. Youngov poskus z ionoma'' (''Unusual interference experiments I. Young's experiment with two

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

s''), (Obzornik mat, fiz. 41 (1994) 5, pp 119 – 153). # Janez Strnad, ''Nenavadni interferenčni poskusi, Interferenčni poskus z laserjema'' (''Unusual interference experiments, Interference experiment with two

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

s''), (Obzornik mat, fiz. 41 (1994) 6, pp 187 – 190) (PACS 42.50.-p.) # Janez Strnad, ''Premo centralno gibanje J. Vege'' ('' J. Vega's linear central

motion In physics, motion is when an object changes its position with respect to a reference point in a given time. Motion is mathematically described in terms of displacement, distance, velocity, acceleration, speed, and frame of reference to an o ...

''), (Obzornik mat, fiz. 47 (2000) 1, pp 20 – 26). (PACS 01.65.+g, 45.40GJ) # Janez Strnad, ''Nenavadni interferenčni poskusi, Interferenčni poskus z molekulami C₆₀'' (''Unusual interference experiments, An interference experiment with C₆₀ molecules''), (Obzornik mat, fiz. 47 (2000) 2, pp 53 – 56) (PACS 33.80.-b.) # Janez Strnad, ''Precesija enakonočij'' (''The

precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In o ...

of equinoxes''), (Obzornik mat, fiz. 47 (2000) 4, pp 120 – 125). (PACS 01.65.+g) # Janez Strnad, ''Osnovne fizikalne konstante 1998'' (''Fundamental

physical constants A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that cannot be explained by a theory and therefore must be measured experimentally. It is distinct from a mathematical constant, which has a ...

1998''), (Obzornik mat, fiz. 47 (2000) 5, pp 177 – 179). (PACS 06.20.Jr) # Janez Strnad, ''Rubinowicz v Ljubljani'' (''Rubinowics in Ljubljana''), (Obzornik mat, fiz. 47 (2000) 6, pp 144 – 146). (PACS 01.60.+g) # Janez Strnad, ''O gravitacijski konstanti'' (''On the Newtonian

gravitational constant The gravitational constant is an empirical physical constant involved in the calculation of gravitational effects in Sir Isaac Newton's law of universal gravitation and in Albert Einstein's general relativity, theory of general relativity. It ...

''), (Obzornik mat, fiz. 48 (2001) 1, pp 19 – 25). (PACS 04.80.-y) # Janez Strnad, ''Med dvema ognjema?'' (''Between two fires?''), (Obzornik mat, fiz. 48 (2001) 1, pp 92 – 94). (PACS 06.20.Fn) # Janez Strnad, ''Sevalni tlak in P. N. Lebedev'' (''Radiation Pressure and P. N. Lebedev''), (Obzornik mat, fiz. 48 (2001) 1, pp 148 – 153). (PACS 01.65.+g, 45.40GJ) # Janez Strnad, ''Prožni trak kot model vesolja'' (''The elastic ribbon as a model universe''), (Obzornik mat, fiz. 49 (2002) 1, pp 21 – 27). (PACS 98.80.-k) # Janez Strnad, ''Stefanova sila'' (''Stefan's force''), (Obzornik mat, fiz. 49 (2002) 2, pp 58 – 61). (PACS 01.65.+g, 47.15.-x) # Janez Strnad, ''Interferenca elektronov na svetlobi'' (''Interference of

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 ...

s on

light Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...

''), (Obzornik mat, fiz. 49 (2002) 5, pp 148 – 150). (PACS 33.80.-b) # Janez Strnad, ''Vega o obliki Zemlje'' (''Vega on the form of the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

''), (Obzornik mat, fiz. 50 (2003) 1, pp 27 - III). (PACS 01.65.+g, 45.40GJ) # Janez Strnad, ''O elektronih v atomu'' (''On electrons in atom''), (Obzornik mat, fiz. 50 (2003) 3, pp 82 – 85). (PACS 01.40.Ej) # Janez Strnad, ''Kako sem pisal učbenik za fiziko'' (''How I wrote a physics textbook''), (Obzornik mat, fiz. 50 (2003) 5, pp 157 – 160). (PACS 01.40.Gm) # Janez Strnad, ''Bose-Einsteinova kondenzacija cezija'' (''Bose-Einstein condensation of cesium''), (Obzornik mat, fiz. 50 (2003) 6, pp 184 – 191). (PACS 03.75.Fi)

Colloquiums

# Janez Strnad, ''Bose-Einsteinova kondenzacija alkalijskih atomov'' ('' Bose-Einstein's condensation of alkaline atoms''), (FMF, IJS, Ljubljana November 5, 2001). # Janez Strnad, ''Nobelova nagrada za fiziko 2000'' (''

Nobel prize for physics The Nobel Prize in Physics () is an annual award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions to mankind in the field of physics. It is one of the five Nobel Prize, Nobel Prizes establi ...

2000''), (FMF, IJS, Ljubljana November 6, 2000). # Janez Strnad, Alojz Kodre, ''Profesor Kuščer - In Memoriam'' (''In memory of professor Kuščer''), (FMF, IJS, Ljubljana February 2, 2000).

References

# Sandi Sitar (1993), ''Jožef Stefan, pesnik in fizik, Ob stoletnici smrti'' (''Jožef Stefan, the poet and the physicist, By his 100th anniversary of death''), Založba Park, Ljubljana). {{DEFAULTSORT:Strnad, Janez 1934 births 2015 deaths Scientists from Ljubljana Slovenian physicists University of Ljubljana alumni Academic staff of the University of Ljubljana Levstik Award laureates Slovenian science communicators