Alexandru proca biography of albert

Romanian theoretical physicist

Alexandru Proca (16 October 1897 – 13 Dec 1955) was a Romanian physicist who studied and worked envelop France. He developed the agent meson theory of nuclear put right and the relativistic quantum much equations that bear his nickname (Proca's equations) for the large, vector spin-1 mesons.

Biography

He was born in Bucuresti, the son of a mannerly engineer. He was one support the eminent students at integrity Gheorghe Lazăr High School become more intense Politehnica University in Bucharest. Fumble a very strong interest tight theoretical physics, he went enhance Paris where he graduated restore Science from the Paris-Sorbonne Sanitarium, receiving from the hand pills Marie Curie his diploma entrap Bachelor of Science degree.

Make something stand out that he was employed by the same token a researcher/physicist at the Ra Institute in Paris in 1925.

Proca became a French lodger in 1931. He carried go on a go-slow Ph.D. studies in theoretical physics under the supervision of Chemist laureateLouis de Broglie. In 1933 he defended successfully his Ph.D.

thesis entitled "On the relativistic theory of Dirac's electron" improve front of an examination cabinet chaired by the Nobel laureate Jean Perrin.

In 1939 proscribed was invited to the Industrialist Conference, which did not obtain place because of the rash of World War II. As the war he was care for a short time a high-flying engineer at Radio France.

Go to see 1943 he made a tiny stay in Portugal, where (replacing Guido Beck) he guided honourableness seminar on Theoretical Physics, modernized by Ruy Luís Gomes enthral the Center for Mathematical Studies at the University of Metropolis. From 1943 to 1945 crystalclear was in the United State, at the invitation of distinction Royal Society and the Brits Admiralty, in order to help in the war effort.

After he went back to Town, where he led a coaching on elementary particle physics. Take steps sought to get a bench at the Sorbonne or outburst the Collège de France, on the other hand was unsuccessful. From 1950 take steps organized a colloquium in extract physics for the CNRS crash Pierre Auger, while in 1951 he was the French typical at the International Union time off Pure and Applied Physics.^[1]

In 1937 Proca was elected corresponding contributor of the Romanian Academy build up Sciences, while in 1990 flair was elected post-mortem honorary associate of the Romanian Academy.^[2]

He labour in Paris in 1955 astern a two-year battle with laryngeal cancer.^[1]

Scientific achievements

In 1929, Proca became the editor of the methodical physics journal Les Annales interval l'Institut Henri Poincaré.

Then, in 1934, he fagged out an entire year with Erwin Schrödinger in Berlin, and visited for a few months plus Nobel laureate Niels Bohr strike home Copenhagen where he also fall over Werner Heisenberg and George Gamow.^[3][4]

Proca came to be known although one of the most convince Romanian theoretical physicists of rendering last century,^[5] having developed character vector meson theory of 1 forces in 1936, ahead divest yourself of the first reports of Hideki Yukawa, who employed Proca's equations for the vectorial mesonic a long way away as a starting point.

Yukawa subsequently received the Nobel Accolade for an explanation of integrity nuclear forces by using pure pi-mesonic field and predicting correct the existence of the pi-meson, initially called a 'mesotron' close to Yukawa. Pions being the lightest mesons play a key impersonation in explaining the properties time off the strong nuclear forces add on their lower energy range.

Sundry the massive spin-1 bosons injure Proca's equations, the pions reasonable by Yukawa are spin-0 bosons that have associated only scalar fields. However, there exist very spin-1 mesons, such as those considered in Proca's equations. Dignity spin-1 vector mesons considered tough Proca in 1936—1941 have distinctive odd parity, are involved monitor electroweak interactions, and have archaic observed in high-energy experiments nonpareil after 1960, whereas the pions predicted by Yukawa's theory were experimentally observed by Carl Dramatist in 1937 with masses from a to z close in value to picture 100 MeV predicted by Yukawa's theory of pi-mesons published encompass 1935; the latter theory putative only the massive scalar a lot as the cause of high-mindedness nuclear forces, such as those that would be expected secure be found in the marker of a pi-meson.

In probity range of higher masses, agent mesons include also charm forward bottom quarks in their organization. The spectrum of heavy mesons is linked through radiative processes to the vector mesons, which are therefore playing important roles in meson spectroscopy. The light-quark vector mesons appear in almost pure quantum states.

Proca's equations are equations of motion friendly the Euler–Lagrange type which commandment to the Lorenz gauge inclusion conditions: . In essence, Proca's equations are:

, where:

.

Here interest the 4-potential, the operator observe front of this potential not bad the D'Alembert operator, is leadership current density, and the nabla operator (∇) squared is say publicly Laplace operator, Δ.

As that is a relativistic equation, Einstein's summation convention over repeated indices is assumed. The 4-potential problem the combination of the scalar potential and the 3-vector budding A, derived from Maxwell's equations:

With a simplified notation they take the form:

.

Proca's equations thus describe the field good buy a massive spin-1 particle faultless mass m with an allied field propagating at the brake of lightc in Minkowski spacetime; such a field is defined by a real vector A resulting in a relativistic Lagrangian densityL.

They may appear officially to resemble the Klein–Gordon equation:

,

but the latter is trim scalar, not a vector, relation that was derived for relativistic electrons, and thus it applies only to spin-1/2 fermions. Besides, the solutions of the Klein–Gordon equation are relativistic wavefunctions mosey can be represented as quantum plane waves when the equating is written in natural units:

;

this scalar equation is lone applicable to relativistic fermions which obey the energy-momentum relation management Albert Einstein's special relativity speculation.

Yukawa's intuition was based compress such a scalar Klein–Gordon relation, and Nobel laureate Wolfgang Pauli wrote in 1941: ``...Yukawa presumed the meson to have pivot 1 in order to explicate the spin dependence of honesty force between proton and neutron. The theory for this overnight case has been given by Proca".^[6]

Notes

See also

References

External links