Quantum Sound in the Fabric of the Universe ⚡ экспресс
A key open question in quantum gravity is how continuous spacetime arises from quantum-geometric degrees of freedom in a background-independent setting. One proposal takes a many-body view: spacetime as a hydrodynamic phase of a condensate of quantum geometry atoms, implemented within the group field formalism. Yet quantum fluctuations beyond the mean-field approximation have remained uncharted. By applying Bogoliubov theory to such condensates, we show that the dominant fluctuation contributions appear as collective excitations analogous to phonons in Bose condensates. A group field model describing a nonsingular expanding cosmology enables us to derive the corresponding corrections to Friedmann dynamics. The results identify a new class of quantum-gravitational excitations and forge a link between microscopic dynamics, collective phenomena, and observational signatures of spacetime emergence.
The universe is not a solid monolith, but a canvas of countless quantum threads. Spacetime doesn't flow like water, but vibrates like a tapestry in the wind. For a long time, physicists only saw the overall pattern, neglecting the tremor of individual threads. But if you listen, this tremor merges into something like sound—not audible to the ear, but akin to a wave on a taut string. That's exactly what was described in a new work: the collective trembling of the universe's quantum threads. It resembles gravitational waves, only playing out at the micro level. Interestingly, this ripple slightly alters the pace at which the Universe expands. This was predicted by John Wheeler, and now the ideas developed by Carlo Rovelli are getting a precise framework. Someday, this barely perceptible ringing will be caught by telescopes—and we'll hear the quantum voice of the cosmos.
🎯 In a superfluid, sound doesn't fade—it becomes an endless echo.
🎬 The idea of quantum 'building blocks' of reality is explored in Greg Egan's science fiction novel 'Permutation City', where the universe is a giant cellular automaton.