Gravity and quantum theory cause the Universe to be spontaneously created out of nothing. Most of these universes are quite unlike our own but we select out a subset that are compatible with what we observe.
Please note that Professor Hawking's talk will be broadcasted in the following rooms :
TH auditorium (4-3-006)
TE auditorium (30-7-018)
40-S2-A01
40-S2-C01
BE Meyrin (6-2-024)
BE Prévessin (864-1-D02)