We can’t entirely rule out that the Spot is caused by an unlikely fluctuation explained by the standard model [of particle physics]. But if that isn’t the answer, then there are more exotic explanations.

Perhaps the most exciting of these is that the Cold Spot was caused by a collision between our universe and another bubble universe. If further, more detailed, analysis … proves this to be the case then the Cold Spot might be taken as the first evidence for the multiverse.