If spacetime is made of atoms, as many theoretical physicists these days speculate, could we ever know? You might doubt it. Conventional wisdom says those atoms would be too small, too energetic, or just plain too weird. But Daniele Oriti thinks we have a shot.
Oriti, an Italian theorist working at the Max Planck Institute for Gravitational Physics in Potsdam, draws an analogy with ordinary matter. Its granularity, normally invisible to us, becomes obvious when materials show indubitably quantum features such as superconductivity and superfluidity. Perhaps something like that happens with space. Its underlying quantum nature might percolate to large scales, explaining cosmological mysteries such as dark energy.
Oriti is working to develop so-called group field theory, a quantum theory of gravity that is closely related to the better-known approach of loop quantum gravity. It extends our modern conception of matter, based on quantum field theory, to the putative atoms of spacetime. Ginormous numbers of these atoms woud act collectively to produce spacetime, much as ginormous numbers of H2O molecules give rise to water and its sundry properties. Spacetime might even undergo changes of state—the big bang may have been such an event. Oriti made his case in a winning essay for the Foundational Questions Institute essay contest in 2011.
I chatted with him in June at a conference on the philosophy of quantum gravity, organized by Christian Wüthrich at the University of Geneva and Nick Huggett at the University of Illinois in Chicago.