rahul11 Years agoQuantum theory (otherwise known as quantum physics or quantum mechanics) is one of the two main planks of modern physics or we can say that one of the most important, along with general relativity, and between them the two theories claim to explain virtually everything about the universe. General relativity gives us our picture of the very big (space-time and gravity), while quantum theory gives us our picture of the very small (atoms and their constituents).