James Kakalios is a funny leger aficionado . As a professor in the School of Physics and Astronomy at the University of Minnesota , he ’s been teaching the very popular course " Everything I involve to be intimate About Physics I Learned From Reading Comic Books" since 1988 . Today we ’re delirious to publish this excerpt from the fresh second edition of his book , The Physics of Superheroes . Enjoy !
Fresh Air Underwater?
The most striking ability of Aquaman , as well as that of Marvel Comics Prince Namor , the Sub - Mariner , and all the other denizens of comic Scripture ' many distinguishable underwater cities of Atlantis , is the ability to educe atomic number 8 directly underwater . Without this superpower , there does n’t seem to be much point to being a water - establish superhero . It turns out that this is the one special major power that requires the little miracle exception from the practice of law of nature . Why should n’t Aquaman breath through water — after all , we do !
Everyone knows that drowning results when the lung fill up up with water . What is less commonly greet is that normal breathing would be out of the question without a small amount of water in the lungs . Fresh air comes in through the nose , and travels down the bronchial subway , where it is warm up to the body ’s temperature and pre moistened . In fact , the air has to be at 100 percent proportional humidity as it go down the ever more fine branching tubes on its manner to the alveoli — small niggling spherical bud where the exchange of oxygen and carbon dioxide pass . These pockets are roughly 0.1 to 0.3 millimetre in diameter , smaller than the period at the terminal of this prison term . On the other side of the bulwark of the alveolar bud are the capillary — very narrow-minded descent vessels in which plasma and red blood cells flow to drop off carbon dioxide molecules and pick up atomic number 8 molecule on their room to the pump . The capillary are narrow for the same reason that the alveolar spheres are so small — to maximize the ratio of surface country to volume . Since the gas rally accept place only through the walls of the alveoli and the capillaries , the more Earth’s surface area there is , the more part there are for possible accelerator pedal diffusion to occur .
But even this very thin water layer in the air sac should be physically open of causing asphyxiation . The same physics responsible for shine dewdrops should grow sharp shortness of breath , or bad . The magnitude of surface tension in the water layer is sufficient to cause the low alveolar bud to come together up entirely , so that even bass breaths would not be enough to furnish the necessary pressure to drive the atomic number 8 atom into the blood stream . What save us from choking on an amount of water that could not in full fill a thimble ? liquid ecstasy !
control surface tension is the name give to the pull force-out that result from the attractive feature of molecules in the fluid ( let ’s say H2O ) to each other . Such an attractive force must of course exist — or else the atoms or atom in the liquid would fly aside from each other as they return to the evaporation United States Department of State . For most liquids , this force is a comparatively weak static cling ( call the van der Waals draw ) that arises from vacillate charge distributions in the mote . The strength ca n’t be too strong , for the water particle must be capable to move past each other and flow through hosiery or fill up the volume of a container in exactly the manner that a solid does n’t . We ’ll discuss van der Waals subsequently on , when we consider the physical science that enable gecko lizard and Spider - Man to climb up bulwark and across ceilings .
This tendency of water to curve is less charming when it force the walls of our alveoli to constrict , requiring utmost pressures to keep the gentle wind bud open . When faced with the problem of diminish the surface tenseness in alveolian urine in the developing of our physiology , rude extract pick out the same solution we employ when washing our wear . The cells in the alveolar wall generate a substance known as " pulmonary surface-active agent . “ The first full term just refers to the lungs , while a " surfactant" is a retentive , skinny molecule with different chemical groups at either end . Electrostatic interactions lead in one last of this mote being attracted to the charge distribution in piss atom , while the other goal is repelled by those same charges . If the long skinny molecule is moderately rigid , like a spine , then a large collection of such atom will orient themselves so that all of the regions that are fight off by water are pointing in one direction ( typically where there is a low concentration of water ) , while those ends that are attract to pee will offer into the fluid . The region where the surfactant molecules can satisfy both ends at the same meter is at the water - melodic line interface , with the piss - attracting death inserted into the water and the water - avoid goal protruding out into the air . In such a configuration , the surfactant intervene with the water - water soldering at the surface of the pee bed . This tighten the cohesive force between piddle atom that was the source of the surface tautness . Without pulmonary surface-active agent , the air sac — fundamentally breeze house of cards in water — are unable to effectively help natural gas exchange with the blood stream . These essential surfactants do not develop in the foetus until recently in its pregnancy , which is why premature babies may suffer from respiratory distress syndrome , an often - calamitous consideration prior to the evolution of effective artificial surfactants .
A moment ago I pertain to the reason why aerofoil tensity arising from even a thin layer of water in the lungs does not vote out us as " soap . “ While not technically correct , in that pulmonary surface-active agent are not soaps , the converse is true , in that soaps are surfactant , with urine - appeal and water - repelling chemical substance groups at either end of long skinny , chemical chain - like molecules . Soap help one sportsmanlike up by reducing the surface tension of piddle , so that it can make verbatim liaison with the dirt . That is , wetter make water wetter , and help us breathe slowly as well .
Excerpted fromThe Physics of Superheroes Spectacular Second Edition . Copyright ( c ) 2009 by James Kakalios . reprint by agreement with Gotham Books , a fellow member of Penguin Group ( USA ) , Inc.
