Finally. Thank you. Someone thinking past the punch bowl.

Forget paradoxes, pathogens are the real problem. You don’t need to step on a butterfly to wreck the timeline; you just need a 21st-century rhinovirus and a handshake. Entire villages, gone. History rewritten by a sneeze.

Any responsible time traveler would be sealed head to toe. No exposed skin, no shared air, no hors d’oeuvres. Certainly no cake. You don’t know what yeast does to medieval Europe when it’s had a few centuries of upgrades.