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73 k 8 par8cle reac8ons there are three requirements

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Unformatted text preview: upernovae were seen to be too faint 5/30/13 UW, ASTR 323, SP13, Eric Agol ©2013 6 Cosmological problems •  Cosmological constant problem/dark energy: ____ is it? •  Cosmic coincidence problem: ____ is Ωm,0≈ΩΛ •  Flatness problem: ____ is Universe flat? •  Horizon problem: ____ is CMB isotropic? •  Dark ma]er: _____ is it? 5/30/13 UW, ASTR 323, SP13, Eric Agol ©2013 7 Early Universe T=2.73K(1+z)=2.73/a At high temperatures, photons can collide to produce par8cle and an8- par8cle pairs 5/30/13 1031 deg @ 10- 43 s Expansion cools the Universe UW, ASTR 323, SP13, Eric Agol ©2013 Now 4 X 1017 s; 2.73 K 8 Par8cle reac8ons •  There are three requirements for par8cle reac8ons to occur: enough ________, _______, and _____ •  If these are sa8sfied, then the reactants & products approach sta8s8cal equilibrium...
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