scott123 wrote:

> Eggs begin with a very tiny air pocket that grows over time. They crack
> because this air pocket expands when heated. The fresher the egg, the
> smaller the air pocket, the less tendency toward cracking. At the same
> time, though, the fresher the egg, the harder they are to peel.
>

This is not completely accurate. Egg shells are permeable to air, so as
the air exmands it passes thru the shell - this is why you see bubbles
rising from eggs in the hot water. The main reason eggs crack while
being boiled is that they are already cracked - small hairline cracks
that are not visible initially. Knocking around in too-rapidly boiling
water is another reason. Temperature shock is not involved. I remember
seeing Julia Child take eggs from an ice water bath directly to boiling
water with no cracking.

Peter