California Institute of Technology (Caltech) - Division of Physics Mathematics & Astronomy
PIRSA:12020152
How do snowflakes form? What creates their complex, symmetrical and strikingly beautiful shapes? Is it true that no two are exactly alike? Kenneth Libbrecht of Caltech, will reveal the secrets of snowflakes and the molecular dynamics of crystal growth through spectacular photographs of these miniature ice sculptures.
We relate the discrete classical phase space of loop gravity to the continuous phase space of general relativity. Our construction shows that the flux variables do not label a unique geometry, but rather a class of gauge-equivalent geometries. We resolve the tension between the loop gravity geometrical interpretation in terms of singular geometry, and the spin foam interpretation in terms of piecewise-flat geometry, showing that both geometries belong to the same equivalence class. We also establish a clear relationship between Regge geometries and the piecewise-flat spin foam geometries. All of this is based on arXiv:1110.4833.