I assume you dropped out of graduate school and now have a nice paying job with the government. (Good move!)
Your professor's lecture was not about the "fall of the years" but the "fall of the jers." That's why my recent "epistle," as you so eloquently termed it, rang familiar. In reconstructive phonology - the Russian Ø and ß are termed jers. To be more exact, the Ø is called the "front jer" and the ß the "back jer." This describes their articulation as short vowels, equal roughly to the /i/ in "pit" (a "front short vowel") and the /u/ in "put" (a "back short vowel"). Some of this was mentioned in my earlier "epistle."
You'll also recall that syllables in Old Russian tended toward something called "pleophony," meaning they tended to end in vowels. As vowels - albeit short vowels - the jers played an important role in "pleophony."
But to tell our tale correctly, we need to go back to a time before Russian was a written language, to a time before it even emerged from proto-East Slavic as a separate language. Let's compare some proto-East Slavic forms with their Modern Russian counterparts. In the examples below, the asterisk (*) indicates reconstructed proto-East Slavic forms. Notice all the jers:
*ÓßÎß - ÓÏÎ
*ÓßÎÁ - ÓÎÁ
*ÏÔØÃØ - ÏÔÅÃ
*ÏÔØÃÁ - ÏÔÃÁ
*Ëß ÎÅÍÕ - Ë ÎÅÍÕ
*Ëß ÍØÎÅ - ËÏ ÍÎÅ
*Óß ÎÉÍØ - Ó ÎÉÍ
*Óß ÍßÎÏÊ - ÓÏ ÍÎÏÊ
*ÛØÌß - ÛÅÌ
*ÛØÌÁ - ÛÌÁ
*ÓßÖØÇÌß - ÓÖÅÇ
*ÓßÖØÇÌÁ - ÓÏÖÇÌÁ
"Wow! Look at all the jers!" you might scream. "Wow! Look at the fleeting vowels! What happened?"
"The fall of the jers! And you thought that old professor's lecture was boring! Hey, are you still awake?"
* * *
The fall of the jers didn't happen all at once. Instead, over the centuries, some jers lost their vocalic quality and stopped being pronounced as vowels. Others turned into the vowels o and e. As a result, Russian developed "fleeting vowels" and "palatalization" - the latter happened in instances where "some" front jers Ø came to be phonetic markers indicating that the preceding consonant was "soft" or "palatalized."
Does this sound confusing? Chaotic? The good news is that there was an "order" to this chaos. Indeed, there were even some "rules" - three of them.
The Rules of Strong and Weak Jers
1. You start at the end of the word and move forward. The first jer you encounter is termed a weak jer, the second a strong jer, then a weak jer, then a strong jer. In other words, from back to front, the jers alternate - weak, strong, weak strong. If you encounter any other vowel, that is, a non-jer, you start counting all over - weak jer...
2. A strong back jer (ß) becomes an o; and a strong front jer (Ø) becomes an Å. This is how "fleeting vowels" arose.
3. Finally, all weak back jers (ß) are dropped, i.e., they go away! And some weak front jers become "soft signs" (Ø) marking palatalization.
Let's look again at our previous list and note the changes from proto-East Slavic to Modern Russian. To illustrate the rules, weak jers have a "strike mark" through them, and strong jers are "underlined:"
ß -> ÓÏÎ
ßÎÁ -> ÓÎÁ
Ø -> ÏÔÅÃ
ØÃÁ -> ÏÔÃÁ
ß ÎÅÍÕ -> Ë ÎÅÍÕ (preps. considered part of word)
ØÎÅ -> ËÏ ÍÎÅ (preps. considered part of word)
ß ÎÉÍ Ø -> Ó ÎÉÍ (preps. considered part of word)
ßÎÏÊ -> ÓÏ ÍÎÏÊ (preps. considered part of word)
ß -> ÛÅÌ
ØÌÁ -> ÛÌÁ
ßÖØÇÌ ß -> ÓÖÅÇ (final Ì dropped)
ØÇÌÁ -> ÓÏÖÇÌÁ
Well, there you have it, more or less - the basics of the fall of the jers. There's more to the story, but we've run out of time for today. Aren't you glad you don't make a living teaching linguistics. Hello? Dude, are you awake?