Explorando a Gravidade Quântica: Físicos Sintonizam o Anel Cósmico de Buracos Negros

Por Whitney Clavin, Caltech, 29 de maio de 2023

Estudos liderados pela Caltech propõem testes novos e rigorosos para a teoria geral da relatividade de Einstein, buscando sinais de gravidade quântica nas ondulações do espaço-tempo geradas por colisões de buracos negros. Um estudo apresenta uma equação para o comportamento do buraco negro nas teorias da gravidade quântica, com base em trabalhos anteriores, enquanto o segundo sugere um método para aplicar essa equação aos dados do LIGO, um observatório de ondas gravitacionais, para detectar possíveis desvios da relatividade geral.

New methods will allow for better tests of Einstein's general theory of relativity using LIGOThe Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory supported by the National Science Foundation and operated by Caltech and MIT. It's designed to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. It's multi-kilometer-scale gravitational wave detectors use laser interferometry to measure the minute ripples in space-time caused by passing gravitational waves. It consists of two widely separated interferometers within the United States—one in Hanford, Washington and the other in Livingston, Louisiana." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]">Data LIGO.

A teoria geral da relatividade de Albert Einstein descreve como o tecido do espaço e do tempo, ou espaço-tempo, é curvado em resposta à massa. Nosso sol, por exemplo, distorce o espaço ao nosso redor de tal forma que o planeta Terra gira em torno do sol como uma bola de gude jogada em um funil (a Terra não cai no sol devido ao momento lateral da Terra).

A teoria, que foi revolucionária na época em que foi proposta em 1915, reformulou a gravidade como uma curvatura do espaço-tempo. Por mais fundamental que essa teoria seja para a própria natureza do espaço ao nosso redor, os físicos dizem que pode não ser o fim da história. Em vez disso, eles argumentam que as teorias da gravidade quântica, que tentam unificar a relatividade geral com a física quântica, guardam segredos de como nosso universo funciona nos níveis mais profundos.

A equação de Dongjun Li e seus colaboradores descreve como os buracos negros tocariam no regime além da relatividade geral. Crédito: Caltech

One place to search for signatures of quantum gravity is in the mighty collisions between black holes, where gravity is at its most extreme. Black holes are the densest objects in the universe—their gravity is so strong that they squeeze objects falling into them into spaghetti-like noodles. When two black holes collide and merge into one larger body, they roil space-time around them, sending ripples called gravitational wavesGravitational waves are distortions or ripples in the fabric of space and time. They were first detected in 2015 by the Advanced LIGO detectors and are produced by catastrophic events such as colliding black holes, supernovae, or merging neutron stars." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]">ondas gravitacionais para fora em todas as direções.

Dongjun Li. Crédito: Caltech

The National Science Foundation-funded LIGO, managed by Caltech and MIT, has been routinely detecting gravitational waves generated by black holeA black hole is a place in space where the gravitational field is so strong that not even light can escape it. Astronomers classify black holes into three categories by size: miniature, stellar, and supermassive black holes. Miniature black holes could have a mass smaller than our Sun and supermassive black holes could have a mass equivalent to billions of our Sun." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]"> fusões de buracos negros desde 2015 (seus observatórios parceiros, Virgo e KAGRA, juntaram-se à caça em 2017 e 2020, respectivamente). Até agora, no entanto, a teoria geral da relatividade passou teste após teste sem sinais de colapso.

Now, two new Caltech-led papers, in Physical Review X and Physical Review LettersPhysical Review Letters (PRL) is a peer-reviewed scientific journal published by the American Physical Society. It is one of the most prestigious and influential journals in physics, with a high impact factor and a reputation for publishing groundbreaking research in all areas of physics, from particle physics to condensed matter physics and beyond. PRL is known for its rigorous standards and short article format, with a maximum length of four pages, making it an important venue for rapid communication of new findings and ideas in the physics community." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]"Physical Review Letters, describe new methods for putting general relativity to even more stringent tests. By looking more closely at the structures of black holes, and the ripples in space-time they produce, the scientists are seeking signs of small deviations from general relativity that would hint at the presence of quantum gravity./p>

The first study, titled "Perturbations of spinning black holes beyond General Relativity: Modified Teukolsky equation," was funded by the Simons Foundation, the Brinson Foundation, and the National Science Foundation (NSF). Other authors include Nicolás Yunes of the University of Illinois at Urbana-Champaign. The second study, titled "Black Hole Spectroscopy by Mode Cleaning," was funded by the Brinson Foundation, the Simons Foundation, NSF, and the Australian Research Council Center of Excellence for Gravitational Wave Discovery (OzGrav). Ling Sun of the Australian National UniversityFounded in 1946, the Australian National University (ANU) is a national research university located in Canberra, the capital of Australia. Its main campus in Acton encompasses seven teaching and research colleges, in addition to several national academies and institutes." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]"Australian National University is also a co-author./p>New methods will allow for better tests of Einstein's general theory of relativity using LIGOThe Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory supported by the National Science Foundation and operated by Caltech and MIT. It's designed to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. It's multi-kilometer-scale gravitational wave detectors use laser interferometry to measure the minute ripples in space-time caused by passing gravitational waves. It consists of two widely separated interferometers within the United States—one in Hanford, Washington and the other in Livingston, Louisiana." data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]"LIGO data./strong>