In the near future, US Navy ships won't use explosive cannons. They will destroy targets 100 miles away with the monster 33-megajoules railgun shown in this video. In the words of Rear Admiral Nevin P. Carr: This "really changes several games."
Right now, Navy railguns could only reach targets 13 miles away. The new railgun reaches any target 100 miles away in six minutes using 33-megajoules of energy, an unprecedented tactical advantage over conventional weaponry like cannons and cruise missiles. To give you an idea of the magnitude of the impact, a megajoule is "roughly equivalent to a 1-ton car traveling at 100 mph." Imagine the effect on a target.
According to the program manager at the Office of Naval Research, Roger Ellis, the gun will eventually reach enemy vehicles and structures 200 miles away with perfect accuracy, using a GPS-based targeting system. Ellis also says that "eliminating explosives from the ship, which brings significant safety benefits and logistical benefits." They just need a constant source of energy in the ship, like diesel engines or a nuclear reactor.
In other words, war has just become greenerer and fasterer and more destructiverer than ever. [Fox News]