Page 104 - The Creation Of The Universe

102 THE CREATION OF THE UNIVERSE

gen and release carbon dioxide into the blood, which conveys it back to
the lungs where it is expelled. The whole thing takes less than half a sec-
ond: "clean" oxygen comes in and "dirty" carbon dioxide goes out.
You might be wondering why there are so many (300 million) of those
little chambers in the lungs. They're there to maximize the surface area that
is exposed to the air. They're carefully folded up to occupy as little space
as possible; if they were unfolded, the result would be enough to cover a
tennis court.
There is another point here that we need to keep in mind. The cham-
bers of the lungs and the capillaries connecting to them are created so small
and perfectly in order to increase the rate at which oxygen and carbon
dioxide are exchanged. But that perfect structure depends on other factors:
the density, viscosity, and pressure of air must all be right in order for the
air to move properly in and out of our lungs.
At sea level, air pressure is 760 mm of mercury and its density is about
1 gram/liter. Again at sea level, its viscosity is nearly 50 times that of wa-
ter. You might think these numbers unimportant but they are vital for our
lives because, as Michael Denton notes:
The overall composition and general character of the atmos-
phere–its density, viscosity, and pressure, etc–must be very similar
to what it is, particularly for air-breathing organisms. 62
When we breathe, our lungs use energy to overcome a force called "air-
way resistance". This force is the result of the resistance of air to movement.
Owing to the physical properties of the atmosphere however, this resis-
tance is weak enough that our lungs can take air in and let it out with a
minimum expenditure of energy. If air resistance were higher, our lungs
would be forced to work harder to enable us to breathe. This can be ex-
plained by an example. It easy to draw water into the needle of an injec-
tor but drawing honey in is much more difficult. The reason is that honey
is denser than water and also more viscous.
If the density, viscosity, and pressure of air were higher, breathing
would be as difficult as drawing honey into a needle. Someone might say
"That's easy to fix. We'll just make the hole of the needle larger to increase
the rate of flow." But if we did that in the case of the capillaries in the