I was going back through the app that gave us the Wendy question, when I found this:
Eggs sink in water when they are fresh and float when expired
I also found this advice:
Fresh eggs will sink to the bottom of the bowl and lie on their sides. Slightly older eggs (about one week) will lie on the bottom but bob slightly. If the egg balances on its smallest end, with the large end reaching for the sky, it's probably around three weeks old. Eggs that float at the surface are bad and should not be consumed. source
Is any of this validated by scientific evidence, or is it just an old wives' tale?