Im completely n00b in biology, just a question arised during the saturday night warmup and there is no better place to get answers :)
So, as probably most of you know, if you want to decide an egg is rotten/gone bad/addled you just put it in a bowl filled up with cold water and some salt. If the egg stays on the bottom of the bowl then it is good. If it os floating on the top of the water then it is rotten/addled.
I cannt imagine other then there is an air bubble in the rotten egg, thats why it is floating.
But how would that air bubble get in the egg?