Science & Environment Theories

In February 1959, nine experienced Soviet hikers died under strange circumstances on a slope of the northern Ural mountains — their tent slashed open from inside, several bodies bearing severe internal injuries without external wounds, and faint radiation on some clothing. The unexplained deaths and Soviet secrecy spawned decades of theories ranging from secret weapons tests to yetis and UFOs, until modern investigations and a 2021 peer-reviewed study pointed to a rare delayed slab avalanche.

Condensation trails (contrails) are the normal ice crystal trails formed behind aircraft at high altitude when hot, humid engine exhaust meets cold air. Distinct from the "chemtrail" conspiracy theory, which claims these trails contain deliberate chemical spraying programs.

The claim that Earth is hollow, with inner surfaces, inhabitants, or openings at the poles. Versions include the 17th-century scientific proposal by Edmond Halley, 19th-century Symmes Hole theory, and 20th-century Nazi/UFO-adjacent versions.

The phenomenon where large groups of people share a vivid but false memory of historical events, objects, or media — coined by researcher Fiona Broome in 2009 after noticing many people falsely remembered Nelson Mandela dying in prison in the 1980s.