More on the A-Word Credit: Anthony Aguirre, Martin Rees, Frank Wilczek Blame: Max Tegmark

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 dse

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Big Bang Zoom Four gradual discoveries: The Universe is much larger than once imagined The Universe can be well described mathematically In most theories, we can’t observe everything that exists There are selection effects

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Big Bang Zoom How big is our Universe?

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Big Bang Zoom Four gradual discoveries: The Universe is much larger than once imagined The Universe can be well described mathematically In most theories, we can’t observe everything that exists There are selection effects - probability that a random point in our observable universe is near the surface of a planet ~

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Big Bang Zoom If we want to test a mathematical theory predicting a larger universe than we can observe, then we’re forced to compute anthropic selection effects. That this is hard isn’t Alex Vilenkin’s fault! So we shouldn’t vent our frustrations on those who try to work on the problem..

Cmbgg OmOl The Standard Model Lagrangian (From T.D. Gutierrez) L=L=

Cmbgg OmOl Standard model parameters: Cosmology Particle physics Required Optional C = h = G = k b = q e = 1 

Cmbgg OmOl How measure ? Standard model parameters: Cosmology Particle physics Required Optional Why these values?

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Cmbgg OmOl

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 wmap movie

(Graphics from Gary Hinshaw/WMAP team)

Fluctuation generator Fluctuation amplifier (Graphics from Gary Hinshaw/WMAP team) Hot Dense Smooth Cool Rarefied Clumpy Brief History of the Universe

MATTER BUDGET INITIAL CONDITIONS (Q) Required Optional  tot   

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 OUR TOOLS

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Smorga sbord

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Measuring clustering

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 History CMB Foreground-cleaned WMAP map from Tegmark, de Oliveira-Costa & Hamilton, astro-ph/

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Boom zoom z = 1000

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Boom zoom z = 2.4 Mathis, Lemson, Springel, Kauffmann, White & Dekel 2001

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Boom zoom z = 0.8 Mathis, Lemson, Springel, Kauffmann, White & Dekel 2001

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Boom zoom Mathis, Lemson, Springel, Kauffmann, White & Dekel 2001 z = 0

Max Tegmark Dept. of Physics, MIT St Thomas March 8, par movies LSS

Max Tegmark Dept. of Physics, MIT St Thomas March 8, par movies LSS Clusters Tegmark & Zaldarriaga, astro-ph/ updates

Max Tegmark Dept. of Physics, MIT St Thomas March 8, par movies LSS Clusters CMB Tegmark & Zaldarriaga, astro-ph/ updates

Max Tegmark Dept. of Physics, MIT St Thomas March 8, par movies Ly  LSS Clusters Tegmark & Zaldarriaga, astro-ph/ updates CMB

Max Tegmark Dept. of Physics, MIT St Thomas March 8, par movies Ly  LSS Clusters Lensing Tegmark & Zaldarriaga, astro-ph/ updates CMB

Max Tegmark Dept. of Physics, MIT St Thomas March 8, par movies Ly  LSS Clusters Lensing Tegmark & Zaldarriaga, astro-ph/ updates CMB

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 But the best is yet to come… Precision, 21cm tomography, …

Cosmological data Fundamental theory ? Cosmological Parameters Nature of dark matter? Nature of dark energy? Nature of early Universe? Why these particular values?

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 PREDICTING

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 PREDICTING It's tough to make predictions, especially about the future. Yogi Berra

Cmbgg OmOl Mass of Earth ×10 24 kg Radius of Earth’s orbit 149,597,870,691 m Mass of electron × kg Bohr Radius of Hydrogen atom x m Parameter status?

Cmbgg OmOl Mass of Earth ×10 24 kg Semimajor axis of Earth’s orbit 149,597,870,691 m Mass of electron × kg Bohr Radius of Hydrogen atom x m Parameter status? Environmental Fundamental?

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Cmbgg OmOl

Big Bang Zoom What are the 4 multiverse levels like? 1)Same effective laws of physics, different initial conditions 2)Same fundamental laws of physics, different effective laws 3)Nothing qualitatively new 4)Different fundamental laws of physics

Cmbgg OmOl A)What determines the constants of nature? B)What do the constants of nature determine? Most of our paper Motivates B Certified 100% philosophy free!

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Cmbgg OmOl Three little numbers:

Cmbgg OmOl R~  /m p  M~ m p Weisskopf 1975 Carr & Rees 1979

Cmbgg OmOl R~ 1/  1/2  1/2 m p 2 M~  3/2  3/2 /m p 2

Cmbgg OmOl R~1/m p 2  1/2  M~  3/2 /m p 2 Weisskopf 1975 Carr & Rees 1979

Cmbgg OmOl R~  /m p 3/2  3/4  M~  3/4 /m p 1/2 Carr & Rees 1979

Cmbgg OmOl R~  /m p 3/2  3/4  M~  3/4 /m p 1/2 Carr & Rees 1979

Cmbgg OmOl

M~  /m p 2 Weisskopf 1975 Carr & Rees 1979

Cmbgg OmOl R~  3  /m p 3  3/2 M~  5 /m p 3  1/2 Carr & Rees 1979

Cmbgg OmOl R~  /m p 5 M~  /m p 5 Carr & Rees 1979

Cmbgg OmOl Based on Carr & Rees 1979, Barrow & Tipler 1986 Inside black hole Below quantum limit

Cmbgg OmOl Based on Carr & Rees 1979, Barrow & Tipler 1986 Inside black hole Below quantum limit Fine-tuning? NO!

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Big Bang Zoom MT 1998, gr-qc/ , Ann. Phys., 270, 1-51

Cmbgg OmOl Most spectacular fine tuning known outside cosmology is arguably in nuclear physics

Cmbgg OmOl Agrawal, Barr, Donoghue & Seckel 1998, PRL, 80, 1822 v/v 0 <0.5: protons (uud) decay into neutrons (udd) v/v 0 <0.8: diproton & dineutron v/v 0 =1: we are here v/v 0 >2: deuterium unstable v/v 0 >5: neutrons (udd) unstable even in nuclei v/v 0 >10 3 : protons (uud) decay to  ++ (uuu) Effect of Higgs VEV v=246 GeV: Savas will return to this!

Cmbgg OmOl Jeltema & Sher, hep-ph/ carbon oxygen 20 M sun 5 M sun 1.3 M sun  +   8 Be 8 Be+   12 C 12 C+   16 O C & O yield given by one parameter that depends on , m u /  QCD, m d /  QCD : Oberhummer, Csoto & Schlattl, astro-ph/ , Science, 289, 88

Cmbgg OmOl 4 effective spatial dimensions: no stable orbits, no stable atoms (Ehrenfest 1917; Tangherlini 1963) MT 1997, gr-qc/ , Class. Quant. Grav., 14, L69-75

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Big Bang Zoom MT 1997, gr-qc/ , Class. Quant. Grav., 14, L69-75

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Cmbgg OmOl HOW TEST/RULE OUT A THEORY? A theory is tested by confronting its prediction f(p) with the observed parameter vector p obs Prediction f(p)  f prior (p) f selec (p) Some fast-and-loose anthropic arguments ignore this factor

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Cmbgg OmOl HOW TEST/RULE OUT A THEORY? A theory is tested by confronting its prediction f(p) with the observed parameter vector p obs Prediction f(p)  f prior (p) f selec (p) Some fast-and-loose anthropic arguments ignore this factor Some papers ignore this factor Neither term is optional!

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 ` V   

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Cmbgg OmOl * 2nd term: involves astrophysics, not biology, since we’re not made of dark matter Challenge: find an example where both terms can be computed. Case study: axion dark matter * 1st term: Prior: analytically computable

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Boom zoom Mathis, Lemson, Springel, Kauffmann, White & Dekel 2001 z = 0

Cmbgg OmOl

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Cmbgg OmOl

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Cmbgg OmOl Measured value=4eV

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Cmbgg OmOl DARK MATTER CONCLUSIONS: Axions theory appears viable If WIMPs contribute up cosmologically relevant dark matter density, then natural to have two dark matters! So any LHC SUSY hints need precision followup, perhaps with linear accelerator Work needed on both terms f prior (p) & f selec (p) Wish list 1: f prior (p) from inflation, landscape Wish list 2: f selec (p) from chemistry & nuclear physics

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Cmbgg OmOl Debating what to choose? There’s no choice! A theory is tested by confronting its prediction f(p) with the observed parameter vector p obs Prediction f(p)  f prior (p) f selec (p) Some fast-and-loose anthropic arguments ignore this factor Some papers ignore this factor No need to choose between traditional and anthropic calculations - neither is optional!

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Q: Are theories like inflation, which predict the existence of other unobservable Hubble volumes (“parallel universes”), untestable? A: No, as long as they also make predictions for things we can observe. Indeed, many inflation models were so testable that they’re already ruled out, like V(  )  4. PHYSICS OR PHILOSOPHY? ?

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Big Bang Zoom Bottom line: Taking anthropic selection effects is not optional when confronting a theory with observation Parallel universes are not a theory but a prediction of certain falsifiable theories (cf. black hole interiors) Critique of anthropic reasoning has largely shifted from “It makes no sense and I don’t like it” to “I don’t like it” I think it’s good that many people disagree with my views!

Max Tegmark Dept. of Physics, MIT St Thomas March 8, 2006 Big Bang Zoom Beware anthropic principle taken to the Epicurean extreme: “The Universe must be such that we like it”

Big Bang Zoom Even if we can’t predict everything, the universe still isn’t so bad!