fresh_42 said:
This is the theoretical limitation, hence finiteness. The real possibilities are much more limited, if we restrict ourselves to reasonable constraints: Say we want to write a standard pop song. Then we have about 3 octaves, 7 scales, 5 values and all in 4/4, 20 seconds for the motive, 40 seconds for the refrain, 4 minutes total. This is what we really have for a composition. And I guess the scales don't even count as being different at court.
This is very far from infinite.
Well good thing music isn't restricted to a single genre then!
But even within that genre, let's reexamine if it really is that restrictive.
I'll (maybe) give you 3 octaves for the vocals only. But there is no such restriction for the music.
7 scales? I don't understand, in what sense are there 7 scales? I really don't know where that number comes from. You can pick one of 12 possible major scales for starters. Well, alright, they won't sound all that different because if you make a melody in C major and the same melody in D major, there won't be any significant difference, it's going to be the same thing but higher. Regardless, you can shift to a different tonality mid song, in fact many pop songs do that. You don't have to use a major scale either. Maybe you want to use the pentatonic minor (very common in blues/rock influenced stuff). Or maybe you want to use the aeolian aka natural minor mode (common choice for sadder songs). Or maybe you want to raise the 7th degree of the aeolian and get the harmonic minor to get a darker/more "eastern"/more classical colour (it was the most common minor in classical music), again a somewhat common choice even in pop, you can hear that in some Billie Eilish songs. Or maybe you want a brighter minor scale, like the dorian, I heard it in a pop song very recently, don't remember who it was from. Santana famously used it frequently. Maybe you want to use mixolydian, which sounds similar to the major scale but maybe a bit bluesier. Maybe you want something even darker and use phrygian, or maybe phrygian dominant to get that flamenco sound. At times some people go really crazy and use some more exotic scales like the double harmonic major/Arabian scale to really give it an "Eastern" sound. You can even throw in a brief whole tone scale passage in there to make it dreamy/disorienting, and you can have one of these scales for your verse and a different for your chorus, or even for the bridge.
5 values? I'm not sure what you mean by that either. Are you saying that you can only have whole notes, half notes, quarter notes, eighth notes and sixteenth notes? That's not exactly true, there are also 32nds and I've even encountered 64ths. There are also triplets and quintuplets of quarters, 8ths, 16ths and even halfs sometimes. I have also seen 7-tuplets and 11-tuplets. You can also combine any value with other values any way you want. And sometimes people play things completely out of time to create a specific feel.
4/4? Why does it have to be in 4/4? I've heard many, many pop songs in 3/4, 6/8, etc. I've also heard pop songs in 9/8, or 7/8, or 5/4. I've heard many pop songs that change time signature half way through, or change tempo half way through.
20 seconds for the motive? Why? That's not necessary.
40 seconds for the refrain? Again, why? And why does there have to be a single refrain? There is even some pop songs with two or three choruses. I don't remember which song it was but I remember a My Chemical Romance (although that's not really a pop band for most people) song that had like 3 or 4 different sections that seemed like choruses, it is pretty unusual but it's not impossible to conceive of a song like that, even one that is shorter than 5 minutes (which is the only real restriction here).
You also say nothing about all the different timbres you can pick, or the different tempos, or the different ways you can combine melodies, or the ways you can add flourishes that don't belong in the scale you picked, or the drum beats, or the sound effects and loops, or spoken word passages, or rapping, or any of these things.
So as you can see there is plenty of room to play around. Sometimes stuff does sound very similar, but that is only because most music during any given time period in any given culture tries to conform to what is most popular at that time, so the same stuff gets repeated a lot. But you can only do that for so long before people get bored, and then someone comes and adds a new element that no one had thought before or had thought before people were ready for it, and music moves on in ways that can't be predicted.
If you have any doubts about any of that I can find examples of pop songs utilising any of these aspects pretty easily.