One hundred international experts meet in Madrid to address the accelerating expansion of the universe and the search for a theory of quantum gravity.
‘Understanding the accelerated expansion of the universe is probably the most important problem in quantum gravity theories today,’ explains IFT researcher Miguel Montero, one of the organisers of the Accelerated Expansion, de Sitter & Strings: From the Swampland to the Landscape (AES3L), which was held from 18 to 20 September at the Instituto de Física Teórica de Madrid (IFT UAM/CSIC).
The event brought together experts from various disciplines, such as string theory and cosmology, to share ideas about the accelerating expansion of the universe and its relation to de Sitter space, a fundamental model that describes a universe in accelerated expansion due to the cosmological constant. ‘We’ve put them all together, like in a pressure cooker,’ adds Montero. ‘The idea is to foster interactions between communities that work on the same topic from different perspectives, but often don’t communicate with each other.’
Accelerated expansion of the universe
The universe is not only expanding, it is expanding at an accelerating rate. More than a hundred years ago, Albert Einstein introduced the cosmological constant into his equations to try to explain a static universe. Today, however, we know that this term implies the existence of a repulsive force acting against the gravitational pull of matter. This dark energy, which plays a crucial role in de Sitter’s model, is a dominant component of the universe and, although we do not yet fully understand its nature, its effect is observable through the acceleration of cosmic expansion.
Theories of quantum gravity
Of the four fundamental forces of physics, gravity ‘stands alone’. Microscopic objects such as electrons and protons are governed by the laws of quantum mechanics, a domain characterised by uncertainty and superposition of states, whereas macroscopic objects such as planets and galaxies follow the laws of gravity. The unification of gravity and quantum mechanics in the form of a theory of quantum gravity is one of mankind’s great challenges and one of nature’s great mysteries.
The AES3L event is part of a tradition of conferences focusing on the Swampland, a research programme that seeks to identify which physical theories are incompatible with quantum gravity. In contrast to this ‘swampland’, string theory promises a ‘landscape’ of solutions consistent with a quantum theory of gravity, including an in-depth analysis of the nature of de Sitter space.
Source: IFT – Communication