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Title: Predicting the Cosmological Constant from the CausalEntropic Principle

Abstract

We compute the expected value of the cosmological constant in our universe from the Causal Entropic Principle. Since observers must obey the laws of thermodynamics and causality, it asserts that physical parameters are most likely to be found in the range of values for which the total entropy production within a causally connected region is maximized. Despite the absence of more explicit anthropic criteria, the resulting probability distribution turns out to be in excellent agreement with observation. In particular, we find that dust heated by stars dominates the entropy production, demonstrating the remarkable power of this thermodynamic selection criterion. The alternative approach--weighting by the number of ''observers per baryon''--is less well-defined, requires problematic assumptions about the nature of observers, and yet prefers values larger than present experimental bounds.

Authors:
; ; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
899842
Report Number(s):
SLAC-PUB-12353
hep-th/0702115; TRN: US200709%%500
DOE Contract Number:
AC02-76SF00515
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CAUSALITY; COSMOLOGICAL CONSTANT; DISTRIBUTION; DUSTS; ENTROPY; PROBABILITY; PRODUCTION; STARS; THERMODYNAMICS; UNIVERSE; Theory-HEP,HEPPH, HEPTH

Citation Formats

Bousso, Raphael, Harnik, Roni, Kribs, Graham D., and Perez, Gilad. Predicting the Cosmological Constant from the CausalEntropic Principle. United States: N. p., 2007. Web. doi:10.2172/899842.
Bousso, Raphael, Harnik, Roni, Kribs, Graham D., & Perez, Gilad. Predicting the Cosmological Constant from the CausalEntropic Principle. United States. doi:10.2172/899842.
Bousso, Raphael, Harnik, Roni, Kribs, Graham D., and Perez, Gilad. Tue . "Predicting the Cosmological Constant from the CausalEntropic Principle". United States. doi:10.2172/899842. https://www.osti.gov/servlets/purl/899842.
@article{osti_899842,
title = {Predicting the Cosmological Constant from the CausalEntropic Principle},
author = {Bousso, Raphael and Harnik, Roni and Kribs, Graham D. and Perez, Gilad},
abstractNote = {We compute the expected value of the cosmological constant in our universe from the Causal Entropic Principle. Since observers must obey the laws of thermodynamics and causality, it asserts that physical parameters are most likely to be found in the range of values for which the total entropy production within a causally connected region is maximized. Despite the absence of more explicit anthropic criteria, the resulting probability distribution turns out to be in excellent agreement with observation. In particular, we find that dust heated by stars dominates the entropy production, demonstrating the remarkable power of this thermodynamic selection criterion. The alternative approach--weighting by the number of ''observers per baryon''--is less well-defined, requires problematic assumptions about the nature of observers, and yet prefers values larger than present experimental bounds.},
doi = {10.2172/899842},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Feb 20 00:00:00 EST 2007},
month = {Tue Feb 20 00:00:00 EST 2007}
}

Technical Report:

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  • We compute the expected value of the cosmological constant in our universe from the Causal Entropic Principle. Since observers must obey the laws of thermodynamics and causality, the principle asserts that physical parameters are most likely to be found in the range of values for which the total entropy production within a causally connected region is maximized. Despite the absence of more explicit anthropic criteria, the resulting probability distribution turns out to be in excellent agreement with observation. In particular, we find that dust heated by stars dominates the entropy production, demonstrating the remarkable power of this thermodynamic selection criterion.more » The alternative approach-weighting by the number of"observers per baryon" -- is less well-defined, requires problematic assumptions about the nature of observers, and yet prefers values larger than present experimental bounds.« less
  • We compute the expected value of the cosmological constant in our universe from the causal entropic principle. Since observers must obey the laws of thermodynamics and causality, the principle asserts that physical parameters are most likely to be found in the range of values for which the total entropy production within a causally connected region is maximized. Despite the absence of more explicit anthropic criteria, the resulting probability distribution turns out to be in excellent agreement with observation. In particular, we find that dust heated by stars dominates the entropy production, demonstrating the remarkable power of this thermodynamic selection criterion.more » The alternative approach - weighting by the number of 'observers per baryon' - is less well-defined, requires problematic assumptions about the nature of observers, and yet prefers values larger than present experimental bounds.« less
  • The contributions of the cosmological constant to the deflection angle and the time delays are derived from the integration of the gravitational potential as well as from Fermat's principle. The findings are in agreement with recent results using exact solutions to Einstein's equations and reproduce precisely the new {lambda} term in the bending angle and the lens equation. The consequences on time-delay expressions are explored. While it is known that {lambda} contributes to the gravitational time delay, it is shown here that a new {lambda} term appears in the geometrical time delay as well. Although these newly derived terms aremore » perhaps small for current observations, they do not cancel out as previously claimed. Moreover, as shown before, at galaxy cluster scale, the {lambda} contribution can be larger than the second-order term in the Einstein deflection angle for several cluster lens systems.« less
  • An analytic expression is derived such that the current profile shape is kept constant during the current build-up phase in tokamaks. The required conductivity profile is parametrized by two externally controllable parameters, I/sub p/ and a/sub p/ in the case of the Gaussian current profile. It is shown that a Gaussian current profile can be maintained for a realistically broad conductivity profile by using the constant q/sub a/ current build-up method even under the condition of a high I/sub p/.
  • Simple functional relations amongst standard model couplings, including gravitional, are conjectured. Possible implications for cosmology and future theory are discussed.