SESZIONE DI TORINO
Vacuum energy plays a central role in modern physics and cosmology. However many important questions regarding vacuum energy remain unsolved. For example, does the zero point energy gravitate? If it does, how is the resulting huge cosmological constant apparently cancelled out? Does gravity have zero point energy? If it does, could the resulting metric fluctuations lead to observable effects? How does a possible measurement of such effects help to select the correct theory of quantum gravity or even the correct theory of everything? The purpose of this talk is to address these issues through quantum decoherence due to metric fluctuations, which is in turn related to the problem of vacuum energy of matter quantum fields. It is shown that (1) vacuum conformal fluctuations of the spacetime metric close to the Planck scale could have an important role in regularizing the total amount of vacuum energy in the Universe. Moreover (2) through their coupling to mass they can induce a loss of coherence of a massive quantum particle propagating in vacuum. It is envisaged that a matter wave interferometer employing massive molecular clusters and working in space under conditions including drag-free and long drift time could potentially detect such a decoherence effect, thus providing a means to probe quantum gravity.

DATA: 03-12-2008