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Cosmology with group field theory condensates

Nov 13
Group Seminar
4:30 pm o'clock to 5:30 pm o'clock
Dr. Steffen Gielen (Perimeter Institute)
SR 02.729

I will outline the construction of quantum states that describe macroscopic, spatially homogeneous geometries, using a Fock space picture for group field theory (GFT). These states can be equivalently described in terms of (open or closed) 4-valent spin networks in LQG, and are similar to coherent states used in the description of Bose-Einstein condensates. Using this property, I will show how an effective dynamics for the “condensate wavefunction” can be computed from the GFT operator equations, which can be interpreted as a quantum cosmology model. In a specific example, the WKB limit reduces, in the isotropic case, to the vacuum Friedmann equation. I will discuss generalisations of the construction, such as anisotropies, inclusion of matter and inhomogeneities.