A Testable Solution of the Cosmological Constant and Coincidence Problems

Douglas J. Shaw; John D. Barrow

doi:10.1103/PhysRevD.83.043518

paper

A Testable Solution of the Cosmological Constant and Coincidence Problems

arXiv:1010.4262 · doi:10.1103/PhysRevD.83.043518

Abstract

We present a new solution to the cosmological constant (CC) and coincidence problems in which the observed value of the CC, $Λ$ , is linked to other observable properties of the universe. This is achieved by promoting the CC from a parameter which must to specified, to a field which can take many possible values. The observed value of Lambda ~ 1/(9.3 Gyrs)^2 $(a pp r o x ima t e l y 1 0^{(} - 120) in P l an c k u ni t s) i s d e t er min e d b y an e w co n s t r ain t e q u a t i o n w hi c h f o l l o w s f r o m t h e a ppl i c a t i o n o f a c a u s a l l y r es t r i c t e d v a r ia t i o n p r in c i pl e . W h e na ppl i e d t oo u r v i s ib l e u ni v er se, t h e m o d e l mak es a t es t ab l e p r e d i c t i o n f or t h e d im e n s i o n l esss p a t ia l c u r v a t u r eo f O m e g a_{k} 0 = - 0.0056 s_{b} /0.5; w h er e s_{b} 1/2 i s a QC D p a r am e t er . R e q u i r in g t ha t a c l a ss i c a l hi s t or y e x i s t, o u r m o d e l d e t er min es t h e p r o babi l i t y o f o b ser v in g a g i v e n L amb d a . T h eo b ser v e d C C v a l u e, w hi c h w es u ccess f u l l y p r e d i c t, i s t y p i c a l w i t hin o u r m o d e l e v e nb e f or e t h ee f f ec t so f an t h r o p i cse l ec t i o na r e in c l u d e d . W h e nan t h r o p i cse l ec t i o n e f f ec t s a r e a cco u n t e df or, w e f in d t ha tt h eo b ser v e d co in c i d e n ce b e tw ee n t_{L} amb d a = L amb d a^{(} - 1/2) an d t h e a g eo f t h e u ni v er se, t_{U}, i s a t y p i c a l occ u r r e n ce in o u r m o d e l . I n co n t r a s tt o m u l t i v er see x pl ana t i o n so f t h e C C p r o b l e m s, o u r so l u t i o ni s in d e p e n d e n t o f t h ec h o i ceo f a p r i or w e i g h t in g o f d i f f er e n t$ Λ$-values and does not rely on anthropic selection effects. Our model includes no unnatural small parameters and does not require the introduction of new dynamical scalar fields or modifications to general relativity, and it can be tested by astronomical observations in the near future.

31 pages, 4 figures; v2: version accepted by Phys. Rev. D

A Testable Solution of the Cosmological Constant and Coincidence Problems

Abstract

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