[wolfekeeper (OP)]

So when you cook stuff, there's apparently, according to the cookbooks, many different ways to boil.

You can 'boil vigorously' or 'simmer' or 'boil vigorously uncovered' etc.

Given that they're all boiling, and presumably at 100 degrees centigrade does that actually make much difference to how things cook?

[damocles]

One possible factor might be the generation of mini shock-waves in vigourously boiling water, and whether or not cell walls get broken down, or whether they remain intact in simmering water. Certainly frankfurts remain intact when simmered, but split open when vigourously boiled (that is a large-scale effect -- not much to do with individual cells, long since departed in those notorious materials!).

There is a neat trick in making stewed fruit or jams, that uses osmotic pressure. If you stew first and add sugar after boiling for awhile, the fruit will all smash up because of the osmotic pressure of the cell contents bursting the cell walls. If you add sugar before stewing (boiling), the osmolality is balanced, and the fruit will remain intact. Some people prefer their rhubarb or jam fruits intact, others prefer them smashed.

[Joe L. Ogan]

It makes a lot of difference how one cooks things.  If you want to tenderize things cook at the lowest boiling tempture that you possibly can.  Thanks for comments, Joe L. Ogan

[Geezer]

I suppose more frantic boiling increases convection in the boiler so that the boilee heats a bit faster.

[damocles]

"boilee"? What an interesting word coinage Geezer! I wonder if that is where our antipodean "billy" comes from (or French "bouilli", a similar origin). -- (wildly off-topic) --

Further to previous comments, rice for English rice pudding or for Italian risotto must be boiled vigourously. It finishes up with a soft fluffy texture -- turns to mush if you over-cook it. Rice for Asian dishes is usually simmered gently. It is aesthetically important that the cooked rice remains in separate individual grains. Different varieties of rice are also involved, of course, but the general principle of simmer for retention of food identity and texture, or boil vigourously to break it up seems to apply in this case as well.

[Geezer]

I think "boilees" were fairly common in your part of World not too long ago.

[wolfekeeper (OP)]

I wonder if things would cook as well if we kept the food just below boiling, like 98 C, and then stirred it vigorously enough, or used ultrasonics to break it up or something.

It could be a lot more efficient because boiling is a horrendously inefficient way to do mechanical things.

[JP]

In home brewing beer, its standard practice to use a vigorous boil in order to drive off a lot of volatile compounds from the grain that you don't want in the finished beer.  One particular culprit is dimethyl sulfides: http://www.homebrewtalk.com/wiki/index.php/DMS.  I imagine in most cooking, though, this isn't an issue. 

[Geezer]

Of course, there is another dimension to consider. Is the lid on, off, or partially on?
 
Mrs G maintains the lid must be partially on when boiling spuds. Also, I think the lid is supposed to be off entirely when boiling pasta.

[CZARCAR]

ithinx pressure is a factor= hard boil evaporates faster but builds up presssure to do so? Pasta box sez simmer & stir often. 98*C + stirring ?