This story is part of our “Cosmic Perspective” special, which confronts the incredible vastness of the universe and our place in it. Read the rest of the series here.
We tend to think of space-time as the underlying structure of the universe, but whether it’s truly fundamental, or whether it arises from something much deeper, is a question that keeps physicists up at night. “It’s not a philosophical question to debate over a beer,” physicists say. Marika Taylor “This is something that actually gets factored into the calculations that people make,” say researchers from the University of Birmingham in the UK.
A great place to start is quantum mechanics, which describes the behavior of elementary particles. One of the core tenets of this notoriously counterintuitive theory is that connections between particles can transcend our usual concepts of space and time. This happens through a phenomenon called quantum entanglement, in which particles can affect each other’s properties even when they’re half a universe apart.
Cosmologists now generally accept that quantum entanglement is intimately connected to the emergence of space. If we know the degree of quantum entanglement between two quantum particles, we can derive the distance between them. When we do this for a network of many particles, a geometry begins to form from which we might call space emerges. In other words, space may emerge from quantum entanglement.
Entanglement and space-time
Furthermore, advances in string theory, a candidate theory of everything, say that what happens in the universe can be explained entirely by data held at the exterior, or boundary, of that space.