Be prepared for the experiment: you must have a bottle with a wide neck, a newspaper, matches, a hard-boiled egg.

At first, throw a burning newspaper in the bottle. When it is completely burned, seal the neck tightly (very tightly so the air cannot get it) with a hard egg without a shell — like a cork.

In a few minutes, you will see that egg starts to lengthen and retract inward until it drops to the bottom.

How did this happen? The egg is wider than the bottleneck, after all!

That’s how it happened. There was an air in the bottle that we heated up with a burning newspaper, the air expanded and most of it came out of the vessel. Then we plug the neck with an egg tightly. So the surrounding air is pressing on the egg from above, and discharged air from below enables an egg into the bottle. Outside air pushes the egg inside because external air pressure is higher than the discharged air pressure in the vessel.