Alaimo: Invisible gremlins filling volleyballs

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Why is there air? This was the title of a 1965 Bill Cosby album and part of a very funny bit that Bill did. As Bill tells it, he had a girlfriend in college who, being very smart and a philosophy major, would go around the house asking questions like “Why is there air?” Bill laughs and says that any phys-ed major knows why there is air. It’s to fill up volleyballs and basketballs.
So then why is the sky blue? Science tells us that there are two reasons we see the sky as pale blue. The first reason has to do with the atmosphere. White light that comes from the sun is a mixture of all the colors of the rainbow. But the molecules in the air act like a prism and scatter the white light; colors with shorter wavelengths (blue, indigo, and violet) scatter more strongly than those with longer wavelengths (red, orange, and yellow) while the rest strike the ground, plants, etc. The second reason is that we have three kinds of color receptors in our eye — red, green and blue. When we look up, the scattered blue light hits blue receptor and tells us the sky is blue. Small amounts of scattered green and red light mix with the blue and change our perception of the sky to light blue.
Astronauts on the Moon (or in space) do not have the atmosphere to scatter the light so see the sun only as a very large and bright star against the dark night of space. Skies at dusk (on earth) often seem red because as the sunlight comes through so much more air from the side (as it were) and the blue waves have already “scattered” out, leaving the red, orange and yellow colors to hit our receptors. BTW. The common idea that Mars has red skies is wrong. The idea comes from the Viking (1977) and Pathfinder (1997) probes that took pictures through dust storms. When the weather is nice, Martian skies are blue like ours.
So the above explanations bring me to a very interesting intersection of science and philosophy. Science tell us that certain things are true — that the sky is blue because the molecules in the air have interaction with light waves. But philosophy tells us that this statement has two underlying assumptions that we never mention. The first is that there are, in fact, things called atoms and light waves composed of colors that (though we cannot directly experience them) really exist. We might call this the assumption of an underlying reality. The second thing that is assumed is that somehow one thing causes the other — causation.
What I am trying to get at here (and what I hope will give you something to think about this month) is what the Scottish philosopher David Hume was interested in over 200 years ago. This is the idea that we really have no way to directly perceive this thing called causation and only happen to see things happening one after the other. Even things that we always see happen one after the other. For instance, you drive your car and fill the gas tank. Science tells us that the gasoline runs through the engine, combines with oxygen, releases its stored energy in heat and motion, and then leaves carbon dioxide and water as by products. You know this is so because after you drive around for a while, the tank is empty and you have to refill it to go some more. But Hume suggests that it could just as well be true that invisible gremlins empty your tank periodically and the car moves by some other unexplained mechanism. But even Hume himself said that it was an ‘absurd proposition’ that something should happen without a cause. He only claimed that when we see two events, we do not have enough information to infer that the one causes the other. This skepticism of the underlying reality behind the everyday events in our lives is what makes the difference between the philosopher and the scientist (or the phys-ed student). And it is the intersection of the scientist and the philosopher that makes the world more understandable.
So as the year draws to a close and winter begins many of us celebrate the shortest day of the year (Solstice); the rededication of the Second Temple in Jerusalem (Hannakah); the birth of Jesus (Christmas); and/or family, community and culture (Kwanzaa). I find it interesting that just when the days seem less full of light and warmth these (and other end of year celebrations) all focus on hope for the future. It is comforting to me that whatever our different perceptions of the underlying reality, we seem to be able to agree on some things. Happy Festivus.

Dr. Joe Alaimo is the owner of Ouray Vet and partner of Trail Town Still. The savior of small animals, thirsty people everywhere and a fairly dangerous man with a garlic press.