There might be a hidden 'dark dimension' about the width of a hair that's actually driving the expansion of the universe.
March 23, 2026
Original Paper
Casimir-Induced Quintessence in Dark Dimension
arXiv · 2603.19819
The Takeaway
Most people think of extra dimensions as being impossibly tiny, but this theory suggests one is large enough to almost be seen. It proposes that the energy of particles 'leaking' into this sub-millimeter dimension is what's actually pushing the universe apart.
From the abstract
We investigate a concrete realization of the Dark Dimension scenario, where a single large extra dimension is set at sub-millimeter scales. In this framework, the Casimir energy of bulk fields accounts for the observed dark energy. Working in a 5-dimensional setup with the Standard Model confined to a 4-dimensional brane, we derive the effective action for the radion. We demonstrate that a minimal model comprising only gravity and three right-handed bulk neutrinos typically yields a negative rad