Exploring The Multiverse with Topological Defects
Zhang, Jun.
2016
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Abstract: Inflationary cosmology suggests a nontrivial spacetime structure on
scales beyond our observable universe, the multiverse. Based on the observation that
topological defects and vacuum bubbles can spontaneously nucleate in a de Sitter like
inflating space, we explore two different aspects of the multiverse model in this thesis.
Hence the main body of this study consists of two parts. ... read moreIn the first part, we investigate
domain walls and cosmic strings that may nucleate in the false vacuum. If we live in a
bubble universe surrounded by the false vacuum, as suggested by the eternal inflationary
multiverse model, the nucleating defects could collide with our bubble universe, and leave
potentially observable signals. We investigate different kinds of collisions and their
consequences. We suggest such collisions generically result in signals such as radiation
and gravitational waves or the defects themselves or a combination of both propagating into
our bubble, and therefore provide a new approach to searching for the multiverse. In the
second part, we study the fate of domain walls and vacuum bubbles that could nucleate in
the slow roll inflation. We show that, depending on their sizes, these objects will form
either black holes or wormholes after inflation. We study the spacetime structure of the
resulting wormholes. Our analysis indicates the presence of domain walls and vacuum bubbles
in the slow roll inflation has significant effects on the global structure of our universe,
that is by forming wormholes, it can lead to the picture of a multiverse. We also calculate
the mass spectrum of the resulting black holes and wormholes under certain assumptions. We
argue that the observation of a population of black holes with such mass spectrum could be
considered as evidence of the existence of both inflation and multiverse.
Thesis (Ph.D.)--Tufts University, 2016.
Submitted to the Dept. of Physics.
Advisor: Alexander Vilenkin.
Keyword: Physics.read less - ID:
- h989rf40n
- Component ID:
- tufts:21337
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- TARC Citation Guide EndNote
