Final answer:
Hydrogen cables / electron ionisation is not a medium currently used in data communication. Technologies in use include electromagnetic waves, fiber optics, and copper cables.
Step-by-step explanation:
The medium that is currently NOT used in communicating data is Hydrogen cables / electron ionisation.
Among the options provided, wireless communication through electromagnetic waves, fiber optics using pulses of light, and copper cables transmitting electrical signals are all established mediums for data communication.
Electromagnetic waves are utilized in various forms, such as radio waves, which can carry audio communications and are not significantly absorbed by interstellar dust and gas.
Optical fibers offer advantages like low loss, high bandwidth, and reduced crosstalk due to their ability to carry laser signals over long distances without significant signal degradation.
They are increasingly used for most telephone conversations and Internet communications.
Finally, copper cables have been traditionally used for telecommunication through electrical signals.