Can I find out if an egg is good or bad by putting it in a bowl of water and seeing if it floats?

Don’t trust this method. Says Dr. Marcia Greenblum at the Egg Nutrition Center: “In fact, this test has no relationship to the freshness of shell eggs…a freshly laid egg and an older egg might react very similarly.” Food scientist Susan Brewer explains that this “test” is based on the fact that as eggs age, they produce carbon dioxide, which accumulates in the air sac at the large end of the egg. More gas = floating, but the difference in degree of floating between a good egg and a bad one is small. So, if you need a moment of silence for all the eggs this “test” provoked you to needlessly discard, feel free.
 
Source(s):
University of Nebraska - Lincoln
"Cook It Quick!"
 
Susan Brewer, Ph.D., University of Illinois, Department of Food Science and Human Nutrition