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IQSE AMO/QO Physics Seminar


"Bohr, Landau, and Bronstein: from QED to QG"


Dr. Gennady Gorelik
Boston University

ABSTRACT 

This was one of the most dramatic stories in theoretical physics. It started in the 1929, when the great Niels Bohr, building upon empirical and theoretical indications, suggested that in the future "relativistic theory of quanta ", the law of conservation of energy would break down. In 1931 the 23-years old Russian theorist Lev Landau supported Bohr’s "beautiful idea " by a theoretical consideration claiming that relativistic quantum theory of electromagnetic fields (aka QED) is in general incorrect.

Bohr, however, refuted Landau’s claim, first in oral discussions in Copenhagen, and then in a huge article published in 1933 (and described later as "famously obscure and difficult "). Landau, who considered Bohr as his only teacher, did not accept Bohr’s refutation because it employed "unrealistic " thought experiments.

Here came gravity and a Russian friend of Landau, Matvei Bronstein who tried to implement Bohr’s non-conservation hypothesis in cosmology. Discussing the issue, Landau realized that non-conservation of energy is incompatible with Einstein’s theory of gravity. On the other hand, Bronstein accepted Bohr’s justification of QED and elucidated its physical essence in a short note of 1934. This apparently led Bronstein to the problem of Quantum Gravity (QG), which became the subject of his doctoral dissertation the following year. In his analysis, Bronstein predicted that the solution of the QG problem would require "rejecting our ordinary concepts of space and time, replacing them by some much deeper and non-evident concepts. "

He had no time to take part in this enterprise. At the age of 30 he was arrested (in 1937) and "disappeared " in Stalin’s Great Terror.

Today QG remains to be one of the greatest problems of fundamental physics.

References:
Why is Quantum Gravity so Hard?
http://en.protothema.gr/why-is-quantum-gravity-so-hard/

Matvei Bronstein and quantum gravity
http://www.aracneeditrice.it/aracneweb/index.php/pubblicazione.html?item=9788825505481">/

Matvei Bronstein. Quantum theory of weak gravitational fields (Golden Oldie)"https://link.springer.com/content/pdf/10.1007%2Fs10714-011-1284-5.pdf/">/




Tuesday, April 10, 2018
IQSE Seminar Room, 12:00 Noon
(578 MPHY)


Institute for Quantum Science and Engineering
Texas A&M University

(Pizza and salad to be served at 11:30 am)