What The sign of the oven reads DO NOT OPEN OVEN DURING BAKING. disastrous and futile event is bound to happen if you do?

Opening the oven during baking can cause the cake or bread to fall, due to the rapid change in temperature. This is especially true for delicate baked goods, such as souffles and meringues. Additionally, opening the oven can allow heat to escape, which can prolong the baking time and cause the food to dry out.