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LARGE DISTANCE MODIFICATION OF GRAVITY Gia Dvali New York University

LARGE DISTANCE MODIFICATION OF GRAVITY Gia Dvali New York University. Modified gravity versus dark energy. Dvali, Gabadadze, Porrati; Dvali, Gabadadze;. Deffayet, Dvali, Gabadadze;. Dvali, Gruzinov and Zaldarriaga; Dvali, Turner;. Modified Gravity and Cosmological Constant.

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LARGE DISTANCE MODIFICATION OF GRAVITY Gia Dvali New York University

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  1. LARGE DISTANCE MODIFICATION OF GRAVITY Gia Dvali New York University

  2. Modified gravity versus dark energy Dvali, Gabadadze, Porrati; Dvali, Gabadadze; Deffayet, Dvali, Gabadadze; Dvali, Gruzinov and Zaldarriaga; Dvali, Turner; Modified Gravity and Cosmological Constant Dvali, Gabadadze, Shifman; Adams, McGreevy, Silverstein; Arkani-Hamed, Dimopoulos, Dvali, Gabadadze

  3. Universe’s acceleration: Hubble parameter: Friedmann equation (flat universe) Dark energy or Modified Gravity?

  4. Gravitational shortcut

  5. 8 3 H2-H/rc = GN FRW Equation is modified Early cosmology in normal H>>rc-1 Late cosmology HH=rc-1 At late times Universe is self-accelerating! NO NEED IN DARK ENERGY.

  6. LUNAR RANGING TEST OF MODIFIED GRAVITY Predicted anomalous perihelion precession of the lunar orbit =1.4 x 10 -12 Todays accuracy: =2.4 x 10 -11 10-fold improvement is expected

  7. Why: modified gravity  universes acceleration? Universe’s acceleration at a constant rate implies: CONSTANT CURVATURE = GRAVITON “CONDENSATE” R = 12 H2 = constant Because of acceleration our Universe is filled with a minuscule nearly-constant graviton condensate ~ 10-29g/cm3 BUT, MASSLESS BOSONS DO NOT CONDENSE WITHOUT A SOURCE This is why in Einstein’s gravity the Universe’s acceleration requires a dark energy source!

  8. But, in modified gravity gravitons are no longer massless, and can condense without any dark energy source! Resulting into the self-acceleratedUniverse Friedmannequationfor flat and empty universe: H2 = 0  No expansion Modified Friedmann equation for flat and empty Universe: H2 - H/rc= 0  Acceleration at a constant rate: H=1/rc

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