Letters: Was the Cambridge Boat Race crew decked out in the new colour olo? John Cater thinks so. Plus letters from Anne Cowper, Ian Simmons and Martin S Taylor
Letters: The scientist reflects on a speculative idea about human perception in a 2004 book he co-wrote and, two decades on, an experiment that has produced a colour no one has seen before
Letters: At least some sightings of unidentified anomalous phenomena (UAP) may relate to non-human intelligence, says Prof Michael Bohlander.Plus, letters from Andrew Robinson and Aideen Carty
Letters: Dr Tom McClelland on the consequences of AI consciousness, Michael Webb on protecting creative industries, and Prof Virginia DignumandProf Wendy Hall on the need for a global regulatory framework
The ethics of cloning – and owning – dogs