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<\/div>We tend to think of space-time as the underlying structure of the universe. But whether it really is fundamental or emerges from something deeper is a question that keeps physicists up at night. \u201cIt\u2019s not just a philosophical question that you discuss over a beer,\u201d says Marika Taylor<\/a> at the University of Birmingham in the UK. \u201cIt is actually something that comes into the calculations that people do.\u201d<\/p>\n The best place to start is quantum<\/a> mechanics, which describes the behaviour of subatomic particles. Famously counterintuitive, one of the theory\u2019s core tenets is that connections between particles can transcend our usual notions of space and time. This happens via a phenomenon called entanglement<\/a>, in which particles can affect each other\u2019s properties even when they are half a universe apart.<\/p>\n Cosmologists now generally accept that entanglement is intimately linked to the emergence of space. If we know the degree of entanglement between two quantum particles, we can derive the distance between them. Do that for a network of many particles and you start to form a geometry from which what we call space can emerge. Perhaps, then, space emerges from quantum entanglement.<\/p>\n What\u2019s more, advances in string theory, a candidate for a theory of everything, say that the goings-on in space can be fully described by data held on the outer surface, or boundary, of that space, a phenomenon known as holographic duality<\/a>. Put that together with quantum entanglement and you can build a universe that boasts spatial structure: distances and geometry.<\/p>\n Spyridon Michalakis<\/a>, a mathematical\u2026<\/p>\n<\/p><\/div>\nEntanglement and space-time<\/h2>\n