1) Tos RH 18 establishes that Rabah not Rava predeceased Abaye by 20 years and brings proof to his girsa. Our daf clearly shows Abaye passed before Rava (Amar Rava u'Mi Ika). Why didnt Tosfos bring that as proof!?
2) Does the kollel know from its Tana'im? ?&? ?Amora'im Historical Database or otherwise how old Abaye and Rava were relative to each other???
For example?, ?Abaya could have died first but lived 20? ?years older in age than Rava?, ?if Abaya was much older than Rava?, ?which would answer below question?.?
Daniel Gray, Toronto
1) Great question. Cheilcha l'Oraisa!
The Gemara in Rosh Hashanah does say that Rabah\Rava lived only forty years, while Abaye lived sixty, but that only means that Abaye lived more years than Rabah\Rava, but you are assuming that the Gemara means that they were both born on the same day, and Abaye lived twenty years longer chronologically.
The Gemara does not require more than the fact that Abaye lived sixty years, and Rabah\Rava lived just forty, and it has nothing to do with them outliving each other.
2) Another great question. As for Abaye, there is a clearer birth date, which is found in a document called Igeres Rav Sherira Gaon ("The Epistle of Rav Sherira Gaon," a comprehensive history of the composition of the Talmud, written in the 10th century). Abaye died in year ד׳תרמ״ט (888-889 CE) and, as you know, he was born 60 years before that.
As for Rava, the different opinions depend on whether the Girsa in the Gemara in Rosh Hashanah is Rabah (like Tosfos holds) or Rava (Rashi in there; see also Avodah Zarah 19b).
a) We find in Kidushin 72b that Rava was born "mi'she'Meis Rav Yehudah," and we know that Rav Yehudah died in ד׳תר״י. However, the Rambam has a different version -- "Ad she'Lo Meis" -- which means when Rav Yehudah died, Rava was already alive. There are many proofs to consider, but some hold that Rava was already 21 in ד׳תר״י. (By the way, if so, it turns out that Rava and Abaye were born in the same year, which bonds them even more as friends and colleagues (see also the story in Berachos 48a, how, as children, they sat together in front of Rabah). The reason why Abaye is usually mentioned first is because he was a Rosh Yeshiva before Rava, who became a renowned Rosh Yeshiva after Abaye died. If Tosfos would be sure of the fact that they were born in the same year, he might have brought the proof from Yevamos you suggested in your first question.
b) Rav Sherira says that Rava died in year ד׳תרס״ג (902-903 CE).
If Rava lived only 40 years, there is no way to connect these two facts. And that is another proof to Tosfos that Rabah is the one who lived 40 years.
Kol Tuv,
Aharon Steiner