Monday, April 8, 2013

Seeing air

Last night, I took the big kids to the swimming pool.  When I entered the swimming pool area, I saw something that looked wavy and shimmery.  It was water.  Some time later, on my daughter's advice, I submerged my head while wearing goggles and looked upward.  I saw something that looked wavy and shimmery.  By symmetry with my previous seeing, it had to be... air.

So air is visible, even in moderate quantities.  (Of course one could see air in sufficient quantities, because of how it would dim the light.)


Michael Gonzalez said...

It is a curious thing about how humans talk about the world, that we say things like "underwater" when we really mean "surrounded by water". Stephen Pinker identifies this with a certain "mental physics" that we all share, where we think of a dividing line at the surface of the water, and then anything under that line is "under" the water (despite really being "within" the water). I bring this up, because it seems to me that when you were submerged and looked up, you were still looking at water.

Michael Gonzalez said...

typo *"Steven" Pinker.

William said...

When in air,the surface of the interface with water is visible.

When in water, the surface of the interface with air is visible.

Alexander R Pruss said...

Yes, that's the question: when we look at a body of water, are we seeing the water - as common sense says - or are we seeing its interface with air.

Dagmara Lizlovs said...

When I was 15, I was in this snorkeling class. We would set up stuff at the bottom of the deep end in Crestwood High School's natatorium such as chairs and an under water radio. Then wearing our masks, snorkels and fins, we'd dive down 15 feet, sit in the chairs, this was best done with a heavy weight rubber brick which we held to help us get down faster and stay down, our bodies' buoyancy being a problem. Other problems include having to use some of the breath held for purging water out of one's mask, and that at about a depth of 8ft a valsalva maneuver is a good idea requiring still more of the breath being held. Then, we'd sit in the chairs, 15ft under water, stare up at the surface, and listen to music. Kind of cool looking up through the surface from the bottom!