Detecting or Falsifying the Multiverse

David Spergel

Daan Meerburg

Is our observational Universe unique or is it part of a much larger multiverse?

What are the possible signatures in our observable Universe and how should the signatures be optimally extracted from the data?

*Negative Curvature

*Bubble collisions

*Vacuum from the Multiverse

We can measure the multiverse if:

*Negative Curvature

De Sitter Parent Universe

Emerging Universe needs to be Negatively curved

Improve constraints using multiple data sets: e.g. redshift-space distortions andCMB-lensing galaxy correlations

*Bubble Collisions

Stephen Feeney et al.

See e.g. Matthew Kleban’s group and talk

*Vacuum from the Multiverse

What determines the state ? This will depend on the ground state of the parent Universe (inaccessible spacetime)

Question?

Is there an observational difference between our Universe just being de Sitter or being a de Sitter bubble nucleated in a motherde Sitter space (aka the Multiverse)?

vs

*Vacuum from the MultiversePotential signatures

Requires development of new observational strategies/ estimators

Use CMB, LSS to constrain potential signatures

??