Why does an egg take the same time to cook in water that is just barely boiling as vigorously?

You're right, it doesn't take longer for an egg to cook in barely boiling water than in vigorously boiling water.

The reason is that the temperature at which water boils is a constant (about 100°C or 212°F at standard atmospheric pressure).

Whether the water is barely simmering or bubbling furiously, it's still reaching that same temperature. The rate of heat transfer is different, but the final temperature is the same. Therefore, the cooking time for the egg will be essentially the same.

Here's the breakdown:

* Boiling Point: Water boils at a specific temperature, regardless of how much heat you apply.

* Heat Transfer: Vigorous boiling transfers heat faster than simmering, but the final temperature is the same.

* Egg Cooking: The egg cooks based on reaching a specific internal temperature, which is determined by the temperature of the water.

So, while vigorous boiling might make the egg cook *slightly* faster due to the more rapid heat transfer, the difference in time is usually negligible.