Movie based on Figure 2 of the paper Gravitational waves from vacuum first-order phase transitions: from the envelope to the lattice [arXiv:1802.05712]. This movie originally appeared as Supplemental Material associated with the paper. Caption based on original figure caption: Slices through a simultaneous nucleation simulation with parameters \(R_\mathrm{c} M = 7.15\), \(N_\mathrm{b} = 64\) and \(R_* M = 56.32\) showing the expansion, collision, and oscillatory phase of the scalar field. The scalar field value is shown in blue, and the gravitational wave energy density is shown in red. Note that the range of the colourbar for the gravitational wave energy density changes with time. During the oscillatory phase the gravitational wave energy density becomes very uniform and the “hotspots” are deviations on the sub percent level. The movie is also available on Vimeo, here.