Seminars & Colloquia Calendar

Abstract:   I will discuss some  ideas about the  interface  between the quantum and gravitational realms, and the  emergence of spacetime  itself, which  led  us  to  specific  speculations about the  way in which  anticipated discrete aspects of quantum gravity  might  become manifest at the  
macroscopic  level.   We then will  discuss  an alternative description of  gravitation, initially explored  by Einstein,  and known as Unimodular Gravity,   which  can,   under  suitable  conditions, incorporate  such  novel effects. The result is  a mechanism  for the generation  an  effective cosmological constant,   that  turns out to  be naturally of the same  order of magnitude  as that dictated  by observations.  If this  turns out to be correct, the empirical case  for  the presence of a dominant dark energy component in the present day universe  would   turn out to be  the first  concrete evidence of a discreetness in the  fabric of space-time.  

Based on  “Dark energy from quantum gravity discreteness ”, A. Perez & D. 
Sudarsky. arXiv:1711.05183 [gr-qc] Phys Rev Lett. 122, 221302 (2019).