In the SCG Einstein equation, the zero mode is responsible for the inflationary expansion, and the non-zero modes are responsible for the emergence of structure.

At the early stages of inflation, the scalar field’s vacuum state is homogeneous and isotropic (the Bunch-Davies vacuum).  Now apply to this, the CSL theory (a particular dynamical collapse theory).  The random collapses that result are then responsible for the emergence of structure out of initial homogeneity/isotropy.

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?