Everything humans make eventually becomes junk. Most of it is junk within hours of you buying it. Think of all the throwaway cups and plates from that fast food meal you had last night. The cup might once have been part of a tree in which birds sang and under which bears roamed. The plastic plate was made using energy from oil. Sometime soon, the trees and the oil will run out unless people mend their ways. Even big things like buildings, ships and bridges eventually become junk.