1. The problem statement, all variables and given/known data Maria has an empty bottle with a cork in her backpack. One cold winter day when she had been out skiing, she opened the backpack and she saw that the bottle had been crumpled together. What happened and why? 2. Relevant equations 3. The attempt at a solution My first thought was that the molecules in the bottle didn't get enough energy so they didn't exert a high pressure on the bottle so the pressure outside was bigger. But then I realized that the temperature outside the bottle and inside is the same so why didn't all the molecules in the atmosphere have a smaller pressure on the bottle?