What Is Harmony, Really?
At its simplest, harmony is what happens when two or more notes sound at the same time. But that definition does not capture the magic. Harmony is the emotional language of music -- it is what makes a major chord feel happy, a minor chord feel sad, and a suspended chord feel like it is waiting for resolution. Harmony gives music its direction, its tension and release, its sense of arrival. And despite sounding like a complex music theory concept, harmony is something you already understand intuitively. You recognize a happy chord when you hear it, even if you cannot name it.
Consonance and Dissonance
The two most fundamental concepts in harmony are consonance and dissonance. Consonant intervals -- like octaves, fifths, and thirds -- sound stable and pleasing. Dissonant intervals -- like seconds and sevenths -- sound tense and unstable. Music works by moving between these two states: tension builds on dissonance, and release comes from resolving to consonance. In Blob Opera, you can hear this directly. Drag the blobs close together and you will hear more tension. Spread them apart and you will hear more stability.
Learning by Doing
The best way to explore harmony here is to control one blob with a slow line and listen to how the other voices respond. Repeat the same shape in a different register and compare the result. The experiment's second model harmonizes the input in real time, but Google does not publish the exact rules or chord vocabulary it learned.