A concept page for vacuum structure and observer- or background-dependent particle content.
Vacuum phenomena in QFT show that “empty space” is not trivial. Boundary conditions, strong fields, and accelerated motion can all change how particle content and energy are perceived or extracted.
This page targets high-intuition searches about the Casimir effect, Schwinger pair production, and the Unruh effect while keeping them anchored to the course.
A full lecture reconstruction of the Casimir effect, following the original lecture's development from vacuum wave functionals and vacuum fluctuations to regularization, Euler–Maclaurin analysis, the large-plate asymptotics, and the final Casimir pressure formula.
A full lecture reconstruction showing how a constant classical electric field causes electron-positron pair creation by reducing the Dirac-field evolution problem to independent Landau-Zener transitions for each momentum-spin mode pair.
A full lecture reconstruction showing how the inertial vacuum of a quantum field appears thermal to a uniformly accelerating observer, using a massless scalar field in 1+1 dimensions, two-mode squeezed states, Rindler coordinates, and the emergence of the Unruh temperature.
See how boundary conditions change vacuum modes and generate the force between conducting plates.
Build pair-creation intuition by tilting the energy landscape in a strong electric field.
Compare inertial and accelerated observers on a spacetime diagram to see why the vacuum can look thermal.