Universe Multiverse Do we live in the Best of all Worlds ?
Thomas Naumann
Deutsches Elektronen-Synchrotron DESY Einstein What really interests me is whether God could have created the world any differently.
I ask myself whether, if I were God, I would have arranged the world in such a way. Want big impact? Use big image.
Nr of dimensions
Cosmic content
Anti-Matter Did God Masses 3 have a choice? Forces What if ? What if?
Different number of dimensions
Max Tegmark, Class. Quantum Grav. 14 (1997) 69
2 4
3 Matter Antimatter
1 Big Bang 1 10.000.000.001 ? ??? 10.000.000.000 1 Now 0 Do we live on God’s miscount ?
What if: 1 1 light only 1 2 1.000.001 recollapse 1.000.000 Heaven’s Kitchen: Cosmic Inventory Tune the Universe Balance:
Gravity: Newton GN, Matter Inflation: Big Bang H0, Dark Energy • too much inflation + Dark Energy: gravity can’t form galaxies + stars - no life ! Big Rip
Big Bang Gravity Dark Energy Matter
Expansion Contraction • too little inflation: Repulsion Attraction fast recollapse, no time for life ! Anti-Gravity Gravity Big Crunch Cosmic inventory
• Universe static critical density ⋚ 1 3 5 protons / m
• Universe closed - flat - open • dark energy + matter + curvature 2 + 1 + 0 1999, Nobel 2011 Cosmic inventory • Why is the Universe so flat ? • natural energy scale of gravitation - Planck scale : 19 ~ 1/√GN Newton’s constant ≈ 10 proton masses • Dark Energy density = cosmological constant :
10-120 Planck scale4 • Why so little Dark Energy ? compared to scale of gravity Particle masses
• Our World: neutron 1‰ heavier than proton proton stable, neutron decays
! What if proton heavier than neutron: + proton decays: p → n e $e positron annihilates atomic electron: e+ e- → light n p ! Cosmos would be neutral: only neutrons, photons + neutrinos no protons, no electrons, no atoms, no chemistry - No life !
! No Higgs - electron massless: not bound in atoms, no chemistry - No life ! Greece Kepler 1596 1619
5 Platonic Solids fit 5 known planet orbits Harmonices Mysterium Mundi Cosmographicum Accident or
tuning ?
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13 Multi verse Multiverse “ Newton Opticks, 1704
It may be also allowed that God is able to … vary the Laws of Nature and make worlds of several sorts in several Parts of the Universe. Universe - Multiverse
• short after Big Bang: vacuum fluctuations of space-time + Higgs field: inflation • Superstrings in extra dimensions 10500 compactifications • many Universes with Want big impact? different physics Use big image. Multi
verse 17 B. Carr Universe or Multiverse?
If there is only one universe, you might have to have a fine-tuner. If you don’t want God, you’d better have a multiverse. 1999 1997 2007
S. Lord Martin Rees Lee Smolin Astronomer Royal Weinberg Nobel 1979
Just Six Life of the Living in the Numbers Cosmos Multiverse
cosmological natural the string landscape Our entire universe selection “may explain how the is a fertile oasis of our Universe constants of nature… within the in a multiverse can take values multiverse. suitable for life without being fine-tuned by a benevolent creator.“ Anthropic Principle
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20 Is the world made for us? Criticism Only one Universe Experiments not possible Anthropic Principle: We only observe universes that allow an observer. Tautology, causal circle ? • Multiverse - no science ? Anything goes - quantum mechanics No prediction, only postdiction Fundamental parameters not derived from first principles • What is tuned ? laws, fundamental or environmental parameters ? Vary many parameters ! Einstein: Did God have a choice and could have made the World any differently?
Yes - in a Multiverse ! BosonWhat masses if?
• bosons mediate forces and are quanta of their fields
• photon and gluon = electromagnetic strong bosons of electric + nuclear force are massless !
• W bosons of weak force weak gravity 80x proton mass: govern nuclear fusion in stars Boson Whatmasses if?
• decrease mass by factor of 2: - Sun bigger, colder, burns faster - burn-out within about a billion years - W must not be much lighter for higher life
• Higgs creates mass No Higgs: - weak boson massless - weak Sun burning becomes strong nuclear explosion !