Giving a 19 minute Cliffs Notes version of his book, "Fabric of the Cosmos," theorist Brian Greene explains in this Ted Talk the the basic ideas and history behind string theory, which could at long last unite relativity and particle physics in one comprehensive description of the world. Of interest to the amateur and science enthusiast like me, he uses one particularly effective illustration to answer the obvious question: "If there are more than three dimensions of space, why don't we see them?"
I have one small quibble though. A truly complete theory of the physical world will also incorporate the human analog to the "fundamental, uncuttable constituents of the matter" Greene and other string theorists pursue: the first-person experience. The relentless scrub-scrubbing of hydrogen atoms over 13.6 billion years or so has produced a being capable of pondering its own existence. Sentience, so far, has resisted division and the question "what's it like to be you?", full disclosure.