String theory priors nudge our measurement of the universe's shape

Using CMB, BAO, and supernova data, the authors tested what happens when you replace agnostic priors on dark energy with constraints from string theory's swampland conjectures — specifically banning the cosmological constant and limiting how far a scalar field can roll. The swampland priors mildly shift the inferred spatial curvature compared to standard analyses, suggesting theoretical assumptions quietly embedded in prior choices can matter. It's a concrete example of how string-motivated theory and cosmological observation can, in principle, push and pull on each other.