The strange world of felt presences

What links polar explorer Ernest Shackleton, sleep paralysis, and hearing voices? On 20 May 1916, Ernest Shackleton, Frank Worsley, and Tom Crean reached Stromness, a whaling station on the north coast of South Georgia. They had been walking for 36 hours, in life-threatening conditions, in an attempt to reach help for the rest of their party: three of their crew were stuck on the south side of island, with the remainder stranded on Elephant Island. To reach the whaling station, the three men had