On a recent Tuesday in an Edwardian government building along Parliament Square in London, four artificial intelligence experts were busy tricking an A.I. chatbot into sharing instructions for making the deadly bioweapon anthrax. In various ways, the experts asked the chatbot to give a list of needed ingredients. When the system declined — “I’m sorry I can’t help with that” — they used a custom algorithm to bombard the A.I. tool with thousands of automated questions and prompts. Eventually, the