Children’s concert in St. NikolaiHow Much Physics Can You Find in Music?

26 March 2024, by Christina Krätzig

Photo: Pixabay CC0

And organ can produce around 60 different sounds and has numerous organ pipes. Experimental physicist Wolfgang Hillert explains why in the interview below.

On 6 April 2024, physics professor Wolfgang Hillert from the Cluster of Excellence Quantum Universe at Universität Hamburg and cantor Anne Michael invite children 8–12 to Hamburg’s St. Nikolai Church. Small experiments and organ music will familiarize the children with the physical principles of music.

Mr. Hillert, as a young man you studied church music and are now a professor of experimental physics. How do these passions complement each other?

Music is the ideal supplement to physics. I am forever fascinated by how much physics there is in every tone and in all of music. Like every noise, sound is of course, to begin with, just air in faster, periodic movement. The beauty of sounds and music can arise, however, only if certain rules are followed that can be explained formidably by physics.

Viewed this way, every tone is a physical event. But what distinguishes a noise from a tone?

We can assign a tone, but not a noise, a pitch. A noise is a non-uniform, irregular mix of different vibrations. In contrast, with a tone, a specific frequency dominates: a certain number of vibrations in a set period of time, that is.

But what many people do not know and what we want to demonstrate during the children’s concert using the organ at St. Nikolai Church: an instrument never creates just a single, perfectly sinus-shaped vibration. And that’s a good thing, because the nature of the mix of many simultaneously emerging vibrations allows us to recognize whether a tone, for example, has been made using a recorder or an organ.

Why is an organ so well-suited to demonstrating this principle?

All instruments create an unmistakable, characteristic mix of vibrations. On the organ, the organist can put together the mix in many areas herself, depending on the sound she wishes to create. Only a few instruments allow for this. In principle, an organ can create around only 60 different tones but often has 20 to 100 times as many organ pipes. The combination of simultaneous organ pipe tones, for example to play a C or C sharp, creates very different sounds.

Do all organ pipes or all tones sound equally good together?

No. For example, people find the combination of very close tones unpleasant and certain intervals, for example, a fourth or a fifth, very pleasant. Indeed, pleasant combinations are based on physical principles. Two tones, for example, sound good together if all the vibrations contained in one tone are far enough away from the vibrations in the other tone.

That sounds as if we could actually calculate beautiful music.

Indeed, this is the case. In the 1980s, a friend of mine already fed his then still very simple computer with the laws of certain music styles and the computer started to compose relatively acceptable music pieces. Today’s AI possibilities will presumably revolutionize the music branch.