To me, this song is about Heroin or a drug trip. The weightlessness of two balloons is alluding to the high. Things are only coming through in waves becaues he is in another world.. in his own little bubble. When you are on drugs, you are comfortable, and also numb to the world around you. The ship floating on the horizon is showing that other things are happening out there in reality, but Pink is so far from reality that it is just the horizon to him.

__________________
Beyond your tunnel vision, reality fades like shadows into the night..