Notes

Here’s a classic science experiment that is more than a hundred years old and is guaranteed to amaze your friends. The original demonstration used a hard-boiled egg and a glass milk bottle. Since old milk bottles are hard to come by, I'll be using the glass I have with me. so how does the squishy but solid get mysteriously pushed inside the bottle? The answer is all about air pressure When you first set the egg on the bottle, the air pressure inside the bottle matched the pressure outside, so nothing happened. When you dropped the burning piece of paper into the bottle, it caused the air inside to heat up and start to expand rapidly. That expanding air pushed the egg aside and escaped from the bottle. That's why you saw the egg vibrating at first. When the fire consumed all the oxygen inside then bottle, the flame went out and the remaining air in the bottle cooled down. The egg acted as a seal to prevent outside air from getting in the fill in the extra space. The result was an unbalanced force-the force of the air pushing on the egg from outside the bottle was greater than the force of the air pushing up on it from inside the bottle.

The reason air expands when heated is because the kinetic energy of the air increases and it's atoms and molecules move around more. this means that each atom will take up more space due to it's movement so the air would expand.

The way the egg is able to stay together and fit through the bottle is because the egg whites are made of water and proteins. Proteins are made of long chains of amino acids, but in an egg the chains are clumped tightly together into individual spheres. ("These are called globular proteins.") When the egg is heated, the proteins and water molecules begin the move faster. As they move and collide with each other, the individual protein chains start to unravel, eventually bonding loosely with other protein chains, forming network of protein with water trapped inside. The consistency has changed from runny egg white to a soft solid.

How to get the egg out again? You need to increase pressure inside the bottle. Turn the bottle upside down and tilt it until the small end of the egg is sitting in the mouth of the bottle. Now put you mouth close to the bottle and blow into it, forcing more air into the bottle will increase the amount of pressure inside. When you take your mouth away the egg should pop out.