Records are very easy to understand. Even without a microscope, you can see periodic patterns on test vinyls with beeps. And sound being periodic motion is also obvious from string and percussive instruments.

You can even see tracks starting and ending on pressed CDs under the right lighting with your own eyes. I wonder, is the encoding of silence (approx. 2 seconds) really that different or does the density of grooves or pit/land pattern intentionally differ to help the player seek there faster? I know that uncompressed audio naturally results in a repeated pattern when silence is encoded but given the 8-to-14 modulation and other error correctiion techniques, I find it hard to believe it would result in significantly different density unless they specifically added a special mode just for encoding silence that makes the track brighter-colored for easier coarse seeking.