What research is there on tea preparation? I'm a fan of modernist cooking, and its emphasis on precise measurements and consistency. I'm curious how to apply this to tea preparation - in particular, several things:


It seems to be well established that different types of tea should be prepared at different temperatures - black tea and fruit infusions with boiling water, green tea at 80 degrees centigrade, and so forth. Where/when was this established? How do we know it's optimal for each tea?
Likewise, durations to steep tea seem fairly well established. Is there any research on this? People seem a bit fuzzier on this than on temperatures, with some variation.
There's a lot of variance on the amount of tea leaves per litre of tea, varying between 2 grams per cup (8 grams per litre) and 15 grams per litre! Obviously, this depends on how finely cut the tea is, too. Is there any way I can determine this more objectively than just trying different amounts and tasting?
There seem to be several theories on how best to prepare iced tea. Some suggest using more tea and steeping for longer, some suggest preparing it cold, and so forth. Has anyone determined objectively which are better?


I realize this my come across as rather pedantic, but given the huge variation in preparation suggestions, I'm interested in trying to figure out which work best. Most of the questions above could be answered to some degree, too, with an explanation of what it is - chemically - that makes one batch of tea better or worse, providing a foundation for making these sort of decisions.
The making of tea is a balance between three factors that affect how the flavours of the leaves are infused into the water: time, temperature, and the ratio of leaf surface area to water.

Generally, more of any one of those parameters is balanced by less of the others.
The temperature,however, has a specific minimum requirement, below which certain things simply won't occur. This is why black tea must be made with the water starting at the boiling point, and not at 70 degrees.

As for precision, the problem is mostly defining the result, not the conditions. How do you define a good cup of tea in a way that is measurable and repeatable?

Practically speaking, I find that the different traditions in each tea-drinking culture are a very good starting point to work from. After that, you can adjust and experiment all you want. Remember that traditions can vary from "one for each cup and one for the pot" to the intricacies of a full Japanese tea ceremony.