Can you really "curl" curling stones?

Sorry but I would have to give this one to your friend, its actually fairly easy to control the "curl" on a curling stone, by rotating the handle one direction or the other the stone very drastically and visually has an arc while traveling down the Ice, this is caused by the front edge of the rock being on "fresher" pebble and it slightly melts the ice not giving the trailing edge as much traction and therefore the rock "picks-up" and travels in the direction that it is rotating, after about 15 minuets of being on the ice you will notice this, at the 1 year and above level of experience you can have very precise control of what way you want it to arc and at the pro level they can choose how much they want it to curl, like making it go straight til the last two feet and then bend across or making it go around and behind a different rock for protection. The Brooming pre melts the ice a little bit giving the front edge also a melted surface so it wont pick up and will there fore go straighter and have less curl.