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The Backreaction Conjecture

This presentation discusses the Backreaction Conjecture, which challenges traditional cosmological models by suggesting that the formation of large-scale structure influences the dynamics of cosmic acceleration. We examine the discrepancies in the Standard Model, where baryonic matter, dark matter, and dark energy proportions raise questions about our understanding of the universe. Through generalization of the Standard Model and introducing concepts like effective Friedmann equations, we explore how the interaction between matter and geometry affects the evolution of the universe.

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The Backreaction Conjecture

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  1. The Backreaction Conjecture Thomas Buchert, CRALyon DENET Paris October 25 2011

  2. The Standard Model G= T t 2 a(t) δij ?

  3. The Standard Model works ! Baryons ~ 5% Dark Matter ~ 25% Dark Energy ~70 % Radiation ~ 0.01%

  4. The Standard Model does not work ! Baryons ~ 4% fundamental scalar field / new particles ? Dark Matter ~ 23% other laws of gravitation ? effect of structure ? Dark Energy ~73 % Radiation ~ 0.01% backreaction conjecture

  5. Acceleration in the Standard Model localacceleration ⅓ a(t) =V (t) global acceleration apparentacceleration t 2 a(t) δij Λ

  6. Volume Partitioning

  7. Volume Partitioning D M

  8. Volume Partitioning E D M υ = D M

  9. Acceleration in the Multiscale Model Q D

  10. Acceleration in the Multiscale Model

  11. Generalizing the Standard Model • homogeneous-isotropicsolution of GR • reference to fundamental observers • global background, influencesstructureformation • constant-curvaturegeometry of spacefixed spatialaverages of general GR equations free-fallingobservers in thegeneralspacetime background = average, influences and isinfluencedbystructureformation Riemanniangeometry = dynamicaldegree of freedom

  12. Kinematics • AccelerationLaw : • Expansion Law : • ConservationLaw : • Integrability :

  13. Effective Friedmann Equations : • EffectiveScalarField ( `Morphon´) : Buchert, Larena, Alimi arXiv: gr-qc / 0606020

  14. G=  T m+  Pm+ P = m+  Pm+ P =

  15. Conclusions • structureformationchangesthegeometry of • thebackground • Dark Energy and Dark Matter exist in terms of • “curvatureenergies“ • qualitative understanding of themechanism • iscompleted and itworks in the right direction • quantitative understanding in terms of • non-perturbativemodelsis in itsinfancy • reinterpretation of observations !

  16. Observational Strategies C Template Metrics log(1+z) Larena, Alimi, Buchert, Kunz, CorasanitiarXiv: 0808.1161 Euclid

  17. Further Reading : arXiv: 0707.2153 1103.2016

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