Dynamical collapse theories, recall, unify Penrose’s U and R processes.

Daniel’s approach:  Adapt this to situations involving quantum fields and gravitation, within a semi-classical framework.  During inflation, gravity is classical, but matter is quantum.

Audience:  So the deepest level should be ordinary QM?

Daniel:  It should just be quantum, but whether it’s ordinary QM is unclear.

To address this, Daniel suggests a step back:  We need to identify a physical process that can explain the emergence of the seeds of cosmic structure.

Proposal:  Add to the inflationary paradigm some spontaneous dynamical collapse of the state function.

But:  If one considers a slightly different theoretical quantity, the resulting prediction is not confirmed by observation.

Inflation is modeled by the dynamics of a scalar field.  One then introduces perturbations in the scalar field.  One then quantizes the perturbations in terms of quantum fields.  One can then calculate the two-point function of these field variables.  And one can then extract the “Power spectrum” from this 2-pt function.  And…. eventually this produces a description of the CMB that can be compared, very favorably, with observations.

Inflationary basics:  Takes the universe from a relatively generic state after the Planck era to a state with the seeds of cosmic structure (which we then observe as the CMB, as modeled by the beach ball).

Daniel’s topic:  the emergence of the seeds of structure from quantum fluctuations during the inflationary cosmological era.

This is a situation in which GR, QM, and observation come together (witness the beach ball!).

Recap of the measurement problem:  2 different types of evolution (Penrose’s U Process and R Process).  Why not take Penrose’s suggestion and try to address the measurement problem by incorporating some aspect of gravity?

Daniel thinks philosophers can contribute!  (He even has a beach ball prop.)