The universe as a hologram

Joscha Dutli, Boris Pestoni, University of Zürich AST 202 The Universe: Contents, Origin, Evolution and Future May 24, 2016 Premise

• Not everyone will be able to understand the holographic principle. (Leonard Susskind) Contents

• Black holes: GTR vs QM • Susskind idea • Black holes ➔ universe • Juan Maldecena, mathematical proof • Just a theory or reality? Fermilab experiment What are the information?

• Information: distinction between the fondamental particles that make up the atom in a body and the rest of the universe What is a black hole? Black hole information paradox

Sthepen Hawking Leonard Susskind

• Thermodynamics, general • Quantum mechanics relativity, Hawking • Information can’t be lost radiation • The information of everything that goes into a black hole will be lost Susskind intuition

• Classical physics: a • Quantum mechanics: particle can be only in a particle can be in one place at the same two places at the time same time

• ➔ Holograpic principle Holographic principle idea From black holes to the universe

black hole ➔ universe event horizon ➔ cosmological horizon The universe is finite

• According to the holographic principle, the universe can be described by a polyhedral surface with 10100 cloves: this means that the universe is not infinite, but only very very big! Rigorous proof

• Juan Maldecena in 1997, using string theory, mathematically proves what until then was only a conjecture by Susskind and Gerard 't Hooft. Physical recap of the previous slides

• Black hole: disorder = entropy ~ surface area • Entropy ~ information content => the information-area connection might be extended to any properly defined spacetime. • Amount of information in a 3D region ~ 2D surface area • The total amount of information in the universe is finite Which one is reality?

• Are we the projection or is the outer surface the projection? • Which one is reality? • Whatever happens here, happens there and vice versa ➔ it is our choice to say which is the reality because the mathematics says they’re equivalent Does the theory match the reality?

• It’s a plausible theory. Is it correct?

• Craig Hogan, Fermilab experiment Holographic noise

QM: Heisenberg uncertainty principle

Holographic principle: holographic noise Apparatus Purpose of the experiment

• 1 interferometer: holographic noise should cause the output of an interferometer to jiggle • 2 interferometers, one beside the other: holographic noise would be uncorrelated • 2 nested interferometers: the holographic noise should be correlated and, if the apparatus is big enough, measurable Results and debate

• They found no jiggle ➔ Hogan concludes that the holographic principle is not a correct theory

• Debate: many physicists don’t believe that the holographic principle would require the existence of a noise ➔ the experiment is useless Summary

• Holographic principle is a mathematically theory that could correspond to reality • Unification of gravity and quantum mechanics through string theory. • If it is true, the universe is finite and the total amount of information in the universe in finite Thanks for your attention

Questions?