You can zoom into a high-resolution photo for a long time — until suddenly a smooth face dissolves into individual pixels. Something similar, according to a new study, happens to spacetime itself. The authors propose that tiny intervals of length are not pre-existing 'parts' of the universe but results of measurements. They depend on scale, as if the ruler itself changed its divisions depending on what we measure.
This view leads to a surprising consequence. When you switch to a special description of microscopic lengths, they become discrete and come in equal steps. Any distance at the deepest level can only be assembled from an integer number of 'quanta' of length. Meanwhile, the famous Heisenberg uncertainty relation is not violated but slightly modified, retaining its form.
The behavior of these microscopic lengths follows a flow reminiscent of a river. The flow has 'sinks'—fixed points where the length stops changing. The ordinary continuous space we are used to turns out to be only an unstable regime, like a ball perched on a hilltop. The stable, natural state is a world with a finite minimal length and a grainy structure. The whole construction requires no hard cutoffs or violations of symmetries. The laws of spacetime curvature and speed of light remain intact.
as written by the authors arXiv:2605.24967
The physical origin of spacetime discreteness remains a central open problem in quantum gravity, with most existing approaches relying on specific microscopic structures or model-dependent assumptions. In this letter, spacetime discreteness can arise instead as a consequence of consistent microscopic measurement. By treating infinitesimal spacetime intervals as scale-dependent measurement outcomes rather than predefined geometric entities, we formulate a Micro-Measurement Principle in which spacetime quantum fluctuations are encoded directly in the scaling structure. An equivalent dual representation of microscopic lengths leads to discrete, equidistant measurement outcomes, with the corresponding scaling-deformed uncertainty relation thereby reducing to the standard Heisenberg form. The microscopic lengths are further governed by a geometric renormalization-group flow admitting finite-length fixed points. This construction preserves Lorentz invariance and general covariance without ad hoc cutoffs or symmetry breaking. Our results show that the classical continuous-spacetime description corresponds to an unstable limiting regime, whereas a finite microscopic length and a discrete spacetime structure arise naturally from the fundamental requirements of micro-measurement consistency.
If space were continuous down to infinitesimal scales, an arbitrarily small volume could hold an unlimited amount of information, leading to paradoxes. Quantizing length naturally solves this problem.
In Vernor Vinge's novel 'A Fire Upon the Deep', different zones of the galaxy have different 'graininess' of physical laws, directly affecting the capabilities of civilizations.