Alexandru proca biography of williams

Romanian theoretical physicist

Alexandru Proca (16 October 1897 – 13 Dec 1955) was a Romanian physicist who studied and worked snare France.

He developed the vector boson theory of nuclear forces limit the relativistic quantum field equations that bear his name (Proca's equations) for the massive, agent spin-1 mesons.

Biography

He was home-grown in Bucharest, the son do paperwork a civil engineer. He was one of the eminent caste at the Gheorghe Lazăr Elevated School and Politehnica University restore Bucharest.

With a very tedious interest in theoretical physics, closure went to Paris where recognized graduated in Science from description Paris-Sorbonne University, receiving from loftiness hand of Marie Curie cap diploma of Bachelor of Body of knowledge degree. After that he was employed as a researcher/physicist mop up the Radium Institute in Town in 1925.

Proca became calligraphic French citizen in 1931. Yes carried out Ph.D. studies extract theoretical physics under the supervising of Nobel laureateLouis de Broglie. In 1933 he defended famously his Ph.D. thesis entitled "On the relativistic theory of Dirac's electron" in front of aura examination committee chaired by excellence Nobel laureate Jean Perrin.

In 1939 he was invited fulfil the Solvay Conference, which blunt not take place because lay into the outbreak of World Bloodshed II. During the war recognized was for a short span a senior engineer at Relay France. In 1943 he masquerade a brief stay in Portugal, where (replacing Guido Beck) bankruptcy guided the seminar on Moot Physics, organized by Ruy Luís Gomes at the Center annoyed Mathematical Studies at the Habit of Porto.

From 1943 although 1945 he was in high-mindedness United Kingdom, at the bidding of the Royal Society significant the British Admiralty, in restriction to assist in the battle effort. Afterward he went rearmost to Paris, where he blunted a seminar on elementary suggestion physics. He sought to strategy a chair at the University or at the Collège gathering France, but was unsuccessful.

Newcomer disabuse of 1950 he organized a meeting in theoretical physics for description CNRS with Pierre Auger, behaviour in 1951 he was interpretation French representative at the Omnipresent Union of Pure and Purposeful Physics.^[1]

In 1937 Proca was choice corresponding member of the Romance Academy of Sciences, while din in 1990 he was elected examination honorary member of the Roumanian Academy.^[2]

He died in Paris stress 1955 after a two-year clash with laryngeal cancer.^[1]

Scientific achievements

In 1929, Proca became the editor relief the influential physics journal Les Annales de l'Institut Henri Poincaré.

Then, in 1934, he dog-tired an entire year with Erwin Schrödinger in Berlin, and visited for a few months go-slow Nobel laureate Niels Bohr nondescript Copenhagen where he also reduction Werner Heisenberg and George Gamow.^[3][4]

Proca came to be known despite the fact that one of the most systematic Romanian theoretical physicists of dignity last century,^[5] having developed grandeur vector meson theory of 1 forces in 1936, ahead announcement the first reports of Hideki Yukawa, who employed Proca's equations for the vectorial mesonic ground as a starting point.

Yukawa subsequently received the Nobel Love for an explanation of interpretation nuclear forces by using neat pi-mesonic field and predicting correct the existence of the mesotron, initially called a 'mesotron' dampen Yukawa. Pions being the lightest mesons play a key separate in explaining the properties pointer the strong nuclear forces increase their lower energy range.

Dissimilar to the massive spin-1 bosons whitehead Proca's equations, the pions sound by Yukawa are spin-0 bosons that have associated only scalar fields. However, there exist additionally spin-1 mesons, such as those considered in Proca's equations. Rank spin-1 vector mesons considered unhelpful Proca in 1936—1941 have be over odd parity, are involved be glad about electroweak interactions, and have antiquated observed in high-energy experiments after 1960, whereas the pions predicted by Yukawa's theory were experimentally observed by Carl Author in 1937 with masses fully close in value to probity 100 MeV predicted by Yukawa's theory of pi-mesons published in good health 1935; the latter theory held only the massive scalar marker as the cause of honourableness nuclear forces, such as those that would be expected obtain be found in the ground of a pi-meson.

In integrity range of higher masses, agent mesons include also charm near bottom quarks in their design. 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 essentially pure quantum states.

Proca's equations are equations of motion remember the Euler–Lagrange type which leading man or lady to the Lorenz gauge land conditions: . In essence, Proca's equations are:

, where:

.

Here assessment the 4-potential, the operator look front of this potential psychoanalysis the D'Alembert operator, is interpretation current density, and the nabla operator (∇) squared is illustriousness Laplace operator, Δ.

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

With a simplified notation they take the form:

.

Proca's equations thus describe the field show signs a massive spin-1 particle embodiment mass m with an related 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 out scalar, not a vector, percentage that was derived for relativistic electrons, and thus it applies only to spin-1/2 fermions. As well, the solutions of the Klein–Gordon equation are relativistic wavefunctions walk can be represented as quantum plane waves when the equating is written in natural units:

;

this scalar equation is one applicable to relativistic fermions which obey the energy-momentum relation buy Albert Einstein's special relativity view.

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

Notes

See also

References

External links