Bob and Alice (image) University of Vienna Share Print E-Mail Caption This is the concept of counterfactual communication, where the pigeon and the message do not travel in the same direction. Credit © University of Vienna, created by Jon Ladrón de Guevara Usage Restrictions The image may only be used with appropriate caption or credit. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.