Andrew Huberman· PhD
And the most important point to understand about water in its solid state is that unlike most substances when water is in its solid state, it is actually less dense than when it's in its liquid state. So just think about that. Most substances, like most metals, for instance, when they are in a solid state, they're more dense than when they're in a liquid state. So, for instance, if they're in a solid state, they will sink in a container filled with their liquid form, not water. Water is very interesting because as you cool water and water transitions from a liquid to a solid. It still binds. That is, it can form bonds between those different molecules of water, but the spacing between those H₂O , so again, those peace symbols with hands, so if you had a bunch of those, so if you had, you know, a thousand hands all making peace symbols, they can bond to one another. But when it's cold, those bonds are actually made further apart from one another. And as a consequence, ice, as we all know, floats in water. In other words, put very simply, water is unusual and special in that, in its solid form ice, it is actually less dense than when it's in its liquid form. And that's why ice floats in water.