Why dou use so much water to boil noodles?

Pasta added to water before it starts to boil gets a heat start on mushiness. Pasta quickly begins to break down in tepid water as the starch dissolves. You need the intense heat of boiling water to "set" the outside of the pasta, which prevents the pasta from sticking together. That's why the fast boil is so important; the water temperature drops when you add the pasta, but if you have a fast boil, the water will still be hot enough for the pasta to cook properly. http://whatscookingamerica.net/Pasta_Rice_Main/pasta.htm