[MUSIC] Turning now to nature. There are in fact, principals about the physics of music that apply to all musical cultures. Universal principals about the physics and the acoustics of sound. Let's take a look at just one of them, the overtone series. The overtone series does indeed involve, as the Beach Boys say here, good vibrations. When any string on an instrument or column of air in a tube created by a wind instrument, produces a sound, actually it's producing many sounds through something of an auditory trick or illusion. We hear only the lowest sound in part because it's the loudest. But there are many other strings sounding, as when I play this pitch. [SOUND] Now we can represent this sound by a diagram as you see on the screen. Here we have one string sounding, that's the black string. But it's also being divided. Halves of that string are sounding, thirds of that string are sounding, quarters, fifths, and so on. And this applies to all musical instruments. Now, let's look at these vibrations in a different way, now with the lengths of string standing vertically. The first, and lowest, the one to the left, we call the fundamental. And all the others the overtones. These overtones are small string sections vibrating softly in the background. So, we have the fundamental and the overtones, notice that the first overtone is only half as long as the fundamental. It reflects a two to one ratio, which in music always produces the sound that we call an octave. A distance of eight letter names on the scale. We'll get into all that in our third session. Next comes a rate relationship, a ratio of three to two. Three units of strings sounding against two units. That produces what we call the interval of a fifth. So here's the octave. [SOUND] Here's the interval [INAUDIBLE]. [SOUND] Then we come to four units of string sounding against three, which produces the interval of a fourth. [SOUND] Spans four letter names. Then five to four which gives us interval of the third and so on. [SOUND] Now we can take, as you see on the screen here, the fundamental and all these overtones and apply them to a keyboard. We hear the fundamental note way down here. [SOUND] But we also hear the first overtone, second overtone, third overtone, second, and on up the scale we go. These others, [MUSIC] We hear this and these others are sounding very quiet. These are the overtones at work. The octave the fifth, the fourth, and so on. These are the primary units of music around the world. In Indonesian gamelan music, Chinese music, every music, classical or pop. We all have the same overtones and therefore the basic notion of consonances. We all have the same basic notion of consonance. Because when I play these fundamental notes, this fundamental. [MUSIC] We get this very [SOUND] consonant sound. Knowing this was important to Richard Strauss. He knew it and he used it. He used the fundamental, [MUSIC] In a famous piece called, Also sprach Zarathustra. It's a big piece for a western symphony orchestra. The name is German and it sounds very impressive, very intimidating. But you've heard this piece a thousand times on film and in countless TV commercials. In it, Strauss builds up the beginning of the piece by using the primary overtones [MUSIC] What's this piece about this, Also sprach Zarathustra. Well, said very simply, it's about the dawn of a superman, a superhero who is equated with the rising of the sun and the advent of the new age. How does composer Strauss depict, through music, the rising of the sun and the super hero? Well, let's give a listen. [MUSIC] Well, we start with low rumblings down underneath to suggest primordial slime. Then the sound of the trumpet. Since time immemorial, the trumpet has been associated with the military, the army, with royalty, with power, with the hero. And this powerful sound is moving upwards. It reaches a midway point and then seems to fall back as if the super hero is not quite equal to the task. [MUSIC] Then he tries again, but is now able to reach, [MUSIC] And hold onto the sought after goal. [MUSIC] Eventually we move onto the end, to the conclusion of this opening section where we end with this, a chord progression. Remember, a syntax tells us we've got to go home. [MUSIC] And that final chord there is a very consonant chord, consisting of pitches made up the fundamental, and the first four overtones sounding loudly now all together. But it sounds a lot better when played by a full western symphony orchestra. [MUSIC] Now that's the power of classical music. [MUSIC]