The signature moment of any Olympics opening ceremony is when the cauldron is lit with the Olympic flame to signify the official opening of the games. The flame has traveled via relay from Greece to London, but organizers of the games keep the identity of the person chosen to complete the job a closely guarded secret. Here’s a review of the candidates. The opening ceremony begins at 4 p.m. Eastern, but will only be shown on television at 7:30 p.m., so consider this your spoiler alert if you’re going to be on Twitter or other media.