How to find if and egg is not boiled before cracking it. If I have boiled several eggs and after that someone have mixed them with other not boiled eggs, how can I separate them. Of course I don't want to break the eggs.
What's with all those complicated answers? There's a very easy way to check, one that I always use when I don't know if an egg is boiled or not:
Simply put the egg on a flat surface and spin it fast. If it's boiled, it will continue spinning, otherwise it will stop in 1-2 seconds.
EDIT: As Peteris suggested in his comment, basically a boiled egg will behave as a solid object. So, try to spin your egg 5 full rotations in one push. If you can't make it, it's not boiled.
As a non cooked egg is fluid inside we can make use of the rotational energy stored there. Put an egg on your desk and rotate it fast (like a gyro). Then apruptly stop it with a finger, then release it again.
Case egg was cooked:
The egg will immediately stop spinning
Case egg was raw:
The fluid inside will continue rotation, hence making the egg start rotating again.
Option 1) Put the egg in water. A raw egg will have a tiny stream of air bubbles.
Option 2) Shine a strong flashlight through it. A raw egg will show light all the way through.
Option 3) Spin it on its end. The sloshy innards of a raw egg will cause it to wobble and a cooked egg will spin smoothly.
Shake it in your hand. If you hear it sloshing around inside, it's not boiled.
For the future, you may also wish to store your eggs in a vault, where pranksters can not access them.
Hold it up to a very bright light. If you can't see inside it's been cooked.
It's kind of difficult to make out with just the spinning thing unless you have something to compare with. A BETTER WAY : Give a good spin to the egg along the horizontal axis on a flat surface. If the egg orients itself along the vertical one during its motion, it qualifies as boiled. Simple.