rationalfrummie- I don’t know where all he talk about ‘talking,looking’ etc comes.All of this is correct and,obviously, there are problems in davening while seeing women but this is not the crux of the mechitza. It is simple. The mechitza is to separate the sexes. If they are naturally separated-as with a balcony- you don’t even need a mechitza. Otherwise, you need something to separate them and, learning from hilchos shabbos, anything that is the height of ten tefochim (appx three feet)makes it a different “reshus’ and qualifies as a mechitza.That is why a mechitza of glass is fully kosher (without going into the question of tefiloh and hair,etc)
daasyochid: I thank you for pointing us towards R’Moshe’s teshuvo. However, I read the whole paragraph and re-read and I still don’t understand what R’Moshe zz’l means. The “pashtus’of the gemoro in sukkos is that we are ALLOWED to make an addition to the bais hamikdosh (balcony)to separate the sexes is from novih. There is no indication from the gemoro that there was a need for separation “midoraisa’. And, in truth, there is very little in halocho that tells us to have a mechitza. No mention in shulchan aruch and, by the way, the Rambam clearly indicates that the addition to the bais hamikdosh was TAKEN DOWN after yomtov. So, you can, of course, accept R’Moshe’s reasoning but it is not fully clear.