Topics Science

Question Does water float? Since I came up with this question, it has created quite a lot of debate as it's not as simple as it at first appears. If water doesn't float, then what is the water on the surface moving on, surely it floats as one bit of water on the top can be moving in the opposite direction to the water lower down. However, maybe water is an entity in its own right - something can't float upon itself can it? Help! From Huw Roberts, Wales, UK.

Accepted:
November 18, 2005

Comments

Yes, some of it can, even in its liquid state--if it rises to the top of a volume of water and stays there, and if that's what you mean by "floating in water". Doesn't hotter water tend to do this? All bets are off if you require that at least part of a thing rise above the surface of the volume in order for it to "float in water".

I'm not moved much by the "entity in its own right" worry: some molecules, bits, portions or regions of water can float in others; and maybe some kinds of water float in others, just as some gases sink in others. This answer is particularly compelling once someone reminds us of the obvious...

In philosophy it's often a good idea to begin with a clear case where we are particularly confident about what the right answer is, then move to subtler cases. If the question is whether water ever floats, the clear case is ice.