Space-time Lego

Willem Westra

And

Stefan Zohren

Our goal

Find a theory of Gravity for very, very small scales

Einstein’s theory of gravity: works well for big things such as stars and planets

Small scales: Quantum Mechanics...

The big stuff: Gravity

Einstein’s theory of general relativity, 1918

Gravity: curvature of space-time Matter curves space-time Curved space-time tells matter how to

move

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Gravity = Geometry

The small: Quantum mechanics

Schrödinger’s equation, 1927

Quantum Mechanics Everything that can happen...

does happen

What we see is the stuff that is

most probable to happen

big + small

gravity + quantum

curved space-time + probability

Curved space + quantum Task: count all possible curved space-times Compute the most probable ones

Solution: build space time from little “Lego blocks”

Count the number of ways the Lego blocks can be put together

1+1 dimensional space times One dimension of space One dimension of time Simplest Lego blocks: triangles

Task: count the number of ways one can glue triangles together

Counting the triangles

N N N

Counting the triangles

N N+1 N+1

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Splitting the universe

N N+1 N+1 N

The standard equation

N N+1 N

Missing a move?

N N+1 N