Seminário do Prof. James Burkett Hartle (Professor Emeritus, University of California, Santa Barbara, EUA)

The Impact of Cosmology on Quantum Mechanics (seminário em inglês) Palestrante: Prof. James Burkett Hartle (Professor Emeritus, University of California, Santa Barbara, EUA) Data: 05.08.2020 (quarta-feira) Horário: 14h00min Link: Google Meet (hangouts)

Sumário:

When quantum mechanics was developed in the ’20s of the last century another revolution in physics was just starting. It began with the discovery that the universe is expanding. For a long time quantum mechanics and cosmology developed independently of one another. Yet the very discovery of the expansion would eventually draw the two subjects together because it implied the big bang where quantum mechanics was important for cosmology and for understanding and predicting our observations of the universe today. Textbook (Copenhagen) formulations of quantum mechanics are inadequate for cosmology for at least four reasons: 1) They predict the outcomes of measurements made by observers. But in the very early universe no measurements were being made and no observers were around to make them. 2) Observers were outside of the system being measured. But we are interested in a theory of the whole universe where everything, including observers, are inside. 3) Copenhagen quantum mechanics could not retrodict the past. But retrodicting the past to understand how the universe began is the main task of cosmology. 4) Copenhagen quantum mechanics required a fixed classical spacetime geometry not least to give meaning to the time in the Schrödinger equation. But in the very early universe spacetime is fluctuating quantum mechanically (quantum gravity) and without definite value. A formulation of quantum mechanics general enough for cosmology was started by Everett and developed by many. That effort has given us a more general framework that is adequate for cosmology — decoherent (or consistent) histories quantum theory in the context of semiclassical quantum gravity. Copenhagen quantum theory is an approximation to this more general quantum framework that is appropriate for measurement situations. We discuss whether further generalization may still be required.

Gravação do seminário:

Registro do sexto webinário promovido pelo PPGF. O seminário ministrado pelo Prof. James Burkett Hartle, Professor Emérito da Universidade da Califórnia, em Santa Bárbara, nos Estados Unidos, contou com mais de 160 inscritos/participantes de diversos estados brasileiros, incluindo Amapá, Espírito Santo, Goiás, Maranhão, Minas Gerais, Pará, Paraíba, Piauí, Rio Grande do Sul, Rio de Janeiro, São Paulo e Tocantins; assim como de vários países, incluindo Espanha, Estados Unidos, Índia, Inglaterra, Portugal e Suécia, de três continentes diferentes.

Lista com alguns dos inscritos/participantes: