Did our universe's vacuum state switch on recently?

Physicists tested whether quantum tunneling to a lower-energy vacuum happened recently in cosmic history using galaxy surveys and supernova data. A model where 10% of dark matter converts to radiation at redshift ~7 fits current observations better than standard cosmology and could explain tensions between different cosmic measurements. The constraints are tight but not impossible: 10% drops in vacuum energy remain viable if the decay happened in the last billion years.