This feels relevant: Roger Penrose - Why Did Our Universe Begin? <a href="https://www.youtube.com/watch?v=ypjZF6Pdrws" rel="nofollow">https://www.youtube.com/watch?v=ypjZF6Pdrws</a><p>tl;dw: It is well known that the universe expands, tracing this back in time leads to the singularity called the Big Bang. But is it possible to ask for a "before" the beginning of time? What is time? Time is what we measure with clocks. What are clocks? Something that returns to the same state (say, a pendulum, or the earth orbiting around the sun - a "year"). To be able to build a clock you need mass. Only objects with mass, moving below the speed of light, experience time. In the very far future, after all stars have burned out, the only objects remaining will be black holes. Eventually, even they will decay due to Hawking radiation. So in the end, there will be only expanding space, and radiation that "travels to infinity". Photons themselves do not experience time as they move with the speed of light. Without mass, without anything that has a notion of time, the concept of distance becomes meaningless. The universe will become spacelike. Without distances, the universe may as well be a singular point. Like the Big Bang :)