Figure 1
ESA and the Planck Collaboration/Alan Stonebraker

Figure 1: (Top) In this full sky map, the CMB temperature fluctuations on large scales are more extreme on the right side of the sky. (Bottom) According to the open inflation model, our Universe was born via bubble nucleation inside a larger metauniverse, depicted here with two space dimensions. From the metauniverse perspective, the bubble forms at time T0 and expands outward, as shown with red rings at times T1, T2, and T3. In the three-dimensional spacetime, this expansion forms a “bubble wall” that acts as the starting point (t0) of our Universe. Subsequent times (t1, t2, t3) are defined on hypersurfaces above the bubble wall. The yellow lines show the trajectories of constant positions in space inside this open Universe.