Did early quantum gravity leave detectable marks on cosmic expansion?

If quantum gravitational processes in the early universe left a lingering imprint on how fast space expands, galaxy surveys should see it. Using BAO data from BOSS and DESI plus 1,500 supernovae, this analysis finds no such signal — the correction vanishes completely, capping any 'gravitational memory' effect below 5% amplitude out to redshift 2. The result tightly constrains a whole class of exotic early-universe models without invoking any new physics.