Friend references this video . at 4 minute mark . ish , it states from Hawking that the passengers aboard the train will have traveled 100 years into future , but only aged 1 week . Can you help me understand what their talking about ? Thx ! <| sep |> Fun factnot at all funIt ' s against several widely agreed upon international war treaties that the use of pepper spray , pepper gas , tear gas cannot be used against enemy combatants not civilians in war or military action . Because since these hazardous chemicals restrict the ability for a person to breath normally , and they harm indiscriminately , they are considered to be similar to chemical weapons . Yet most of us live in countries where police , who almost always receive far less training than soldiers , use them indiscriminately against civilians . We shouldn ' t accept that . Weapons that are too dangerous for war should not be used against civilians . Edit ometerstatements 2014 aug 26 f a c e b o o k p o s tsteargaswasbannedwarfare 1993 police 1997 is a Politifact article with citations , that explains the Chemical Weapons Treaty . It was written in 1993 , it incorporated all previously agreed upon chemical weapons treaties and thus replaced them , it was ratified in 1997 . Nearly all member nations of the UN , including Russia and China , agreed to it ' s terms .