Anytime I ask this question it is met with people who angrily argue that there is nothing outside our universe. What proof is there that time started at the moment of the big bang and that there is nothing that our universe is expanding into.. The universe expanding faster and faster everyday does not prove that it is not expanding into another (space time), the fact that everything breaks down at a singularity also does not explain. So how come it is so widely accepted that nothing lies beyond our universe? Especially since we cannot see outside our observable universe?