Precision cosmology and the landscape

Conference · Sun Oct 01 04:00:00 EDT 2006

OSTI ID:934707

Bousso, Raphael; Bousso, Raphael

After reviewing the cosmological constant problem -- why is Lambda not huge? -- I outline the two basic approaches that had emerged by the late 1980s, and note that each made a clear prediction. Precision cosmological experiments now indicate that the cosmological constant is nonzero. This result strongly favors the environmental approach, in which vacuum energy can vary discretely among widely separated regions in the universe. The need to explain this variation from first principles constitutes an observational constraint on fundamental theory. I review arguments that string theory satisfies this constraint, as it contains a dense discretuum of metastable vacua. The enormous landscape of vacua calls for novel, statistical methods of deriving predictions, and it prompts us to reexamine our description of spacetime on the largest scales. I discuss the effects of cosmological dynamics, and I speculate that weighting vacua by their entropy production may allow for prior-free predictions that do not resort to explicitly anthropic arguments.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: Physics Division
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 934707
• Report Number(s): LBNL-415E
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCURACY
COSMOLOGICAL CONSTANT
COSMOLOGY
ENTROPY
FORECASTING
PRODUCTION
SPACE-TIME
UNIVERSE
astrophysics
model
cosmological constant
energy
vacuum
inflationary universe
landscap
string model
talk
Berkeley 2005/10/06