I have a plastic Gatorade type bottle that I reuse. Between uses, I fill it with hot water and shake, and then empty it. Once I empty it, if I put the lid on and wait, the bottle eventually deforms and sucks in on itself. Then when I remove the lid it returns to normal. Why does it deform? Is it the same reason my red plastic gasoline container deforms when its left out in the summer heat all day? Does hot air take up less volume than cool air?