Throughout human history, every time we think we know what the universe is, it turns out that there is not just one of those things, but a lot of them. First we thought the universe was Earth, a sun and a moon, and a sky with a lot of mysterious points of lights. Then there turned out to be a number of planets with their own moons. Then a lot of suns, with their own planets: a lot of solar systems.
What is it
At the foundation of modern theoretical physics lie the equations that define our universe, telling us of its beginnings, evolution, and future. Make even minor adjustments to the fundamental laws of the universe, and life as we know it would not exist. How do we explain this extraordinary fact that our universe is so uniquely fine-tuned for life? Could our universe be just one of infinitely many in a vast multiverse? Does it make sense to talk about other universes if they can never be detected from this one? Can science ever prove or disprove the multiverse theory? Or does the theory make some testable predictions about our finely-tuned universe? John and Ken multiply their thoughts with George Ellis from the University of Cape Town, author of How Can Physics Underlie the Mind?
Part of our series A Philosophical Guide to the Cosmos.