Renate Loll has seen universes that would give Doctor Strange nightmares. She’s explored 3D worlds, flatlands and fractured realities with fractional dimensions. She’s seen universes with gentle curves and universes exploding with violent spikes. She’s witnessed eternally expanding universes and universes in which space fails to exist.
After watching these and an uncountable number of other cosmic histories play out in the digital memory of her computers, Loll no longer takes anything for granted — certainly not the humdrum three dimensions of space and one dimension of time that make up the fabric of our reality.
Loll believes that a careful census of these digital universes could unlock certain aspects of quantum gravity — the more precise quantum theory that presumably underlies Einstein’s notion of space, time and gravity. With general relativity, Einstein defined gravity — a mysterious force — as a consequence of the shape of space and time. A core tenet of quantum theory suggests that this shape is not just one straightforward geometry, but in some sense an average of all possible shapes. To these assumptions, Loll adds the seemingly obvious requirement that causes come before effects. She suspects that these three ingredients — geometry, quantum theory and causality — suffice to enable brute-force calculations of the fundamental structure of reality — no loops, strings or extra dimensions required.
Loll and her collaborators have spent more than 20 years approximating reality using patterns of digital triangles. Their theory, known as causal dynamical triangulations, has shown that if you blend a multitude of possible universes together, you can produce a cosmos that looks a lot like ours. She and her collaborators have also found hints that at tiny scales, space-time may have a completely unexpected structure — a quantum fingerprint of the blending of worlds.