Sitting on my desk right now are my studio headphones with six foot cord. Of course the cord is not six feet long as it sits because much of the length has been coiled up specifically to save space. That coiling may not be needed in the future thanks to researchers at North Carolina State University who have developed a stretchable wire using liquid metal.
Stretchable wires have been developed before by embedding conductors into elastic polymers, but this approach has its limitations. Increasing the amount of the conductor also increases the conductivity, but decreases the elasticity and thus defeats the purpose of a stretchable wire. What the researchers have done though is kept the component separate by having a liquid metal alloy of gallium and indium contained within an extremely elastic plastic. This allows the wire to stretch up to eight times its length, which is orders of magnitude greater than current stretchable wires, while also being ten times more conductive than those same stretchable wires.
The researchers envision this technology being used for headphones, phone chargers, and potentially textiles, but there is one issue to overcome first. There has to be a way to prevent the liquid from leaking out if the wire is ever broken.