Wednesday, April 9, 2008

Super good "Superheroes"

And what sparked your interest in science: Reading those hardcore texts on chemistry and physics or a multitude of comic books chockfull of superheroes with super powers fighting crime and evil scientists? Have you ever heard of Jim Kakalios? Probably not. Jim Kakalios teaches physics at the University of Minnesota. One semester, for a freshman class in physics, he offered a course called "Everything I Know About Science I Learned from Reading Comic Books"...Superheroes and physics. Needless to say, it was a very popular course pulling in students from a variety of areas different than physics. And, he went further and wrote a book called...guess what, The Physics of Superheroes.

In Paul Sorenson's article "Superhero science" Jim Kakalios said this:

"Take Superman," says Kakalios. "In his very first year, he could only leap, not fly. His skin was tough, he had great strength, all because [his home planet] Krypton had larger gravity than Earth." Using the hero's ability "to leap over tall buildings in a single bound" as a benchmark, the class calculated that Krypton's gravity would have to have been six to eight times that of Earth.

That means Krypton had to be either six times larger or six times denser than Earth. Assuming that normal matter on Krypton obeys the laws of physics, the planet could not be six times denser than Earth. "So Krypton had to be six times larger," explains Kakalios. "But any planet that much larger than Earth would have to be a gas giant like Jupiter. Because Krypton had a solid crust supporting buildings and cities, the only other explanation for its increased gravity would be a super-dense—and unstable—material like a neutron star in its core. And that would explain why Krypton exploded."

And this from Toni Feder's article "Teaching Physics with Superheroes" [2002 American Institute of Physics's Physics Today]:

How did Superman get to be so strong? What killed Spider-Man's girlfriend Gwen Stacy? How fast can the Flash run? Jim Kakalios, a condensed matter experimentalist and comics buff, analyzes questions like these from action comics to teach physics in a freshman seminar at the University of Minnesota-Twin Cities.

"Take Superman," says Kakalios. "What does it take to leap a tall building in a single bound?" To find out, Kakalios's students use Newton's laws of motion. "We calculate how much force is required," says Kakalios. That leads to the question, How did his legs get so strong? "Back in the 1930s," Kakalios says, "it was presumed that Superman was so strong because he was acclimated to Krypton's gravity." In the class, the gravitational force of Krypton--Superman's home planet--is calculated to be about 15 times that of Earth's. "We talk about Newton's law of gravity, and then we talk about how you would build such a planet, and not make it a gas giant. I bring in things from different parts of the physics curriculum, and show how interconnected everything is," says Kakalios. "It turns out that the only way we could figure out how to make such a planet, it would be very unstable--it would explode." It's an amusing twist, he adds, "that this is completely consistent with the comics."

Another example is the controversy over the death of Gwen Stacy, who was knocked off a bridge tower. Spider-Man may have been surprised to find her dead when he caught her in his web, but Kakalios's students weren't: By estimating the height of the bridge, Gwen's mass, and the time Spider-Man had to catch her, and then using conservation of momentum, says Kakalios, "it turns out the force has to be at least 10 Gs. If she experienced such a sudden jerk, it's not unreasonable that she would have broken her neck."

The Bernoulli principle, time travel, and the biological and physical feasibility and implications of shrinking to the size of an atom or growing into a giant are among the topics Kakalios's class tackles through comics. The comics don't get the science right all the time, says Kakalios, "but I am struck by how often they do." Over the years, he says, comics have kept up with the times: In the 1940s, a lot of superheroes gained their powers through some mystical artifact from the Far East; in the 1960s, they got them through radioactivity; and, since the 1990s, they get them through genetic engineering. A few years ago, adds Kakalios, results on entangled quantum states found their way into a comic book just months after they were published in Physical Review Letters.

"Interestingly," says Kakalios, "when I talk about comic-book examples, no one asks how they'll use it in real life. They never expected comics to be accurate. Once you show them it's relevant, and develop the physics, I put in real-world applications." For example, he continues, "once we've talked about the Spider-Man story line, and shown that it's conservation of momentum [that delivers the impact that kills Gwen], I bring in airbags. They increase the time to slow your head down. The force to your head can still knock you out, but it doesn't kill you."

It's a sneaky class, says Kakalios. "Basically, the course is really 'physics in the everyday world.' [Students] are so busy eating their superhero ice cream sundaes, they don't notice that I am feeding them their spinach."

Now what about Superman's outfit. Neither is it's origin definitive nor its composition. Superman in a late 1930/early 1940 comic strips vouched that the suit was "...constructed of a cloth I invented myself which is immune to the most powerful forces!" However, the chronicle is better explained and embellished in subsequent issues. But it was basically the product of the three blankets that wrapped Superman from the planet Krypton via the seamstress efforts of his mother Martha Kent. One comic issue hinted that both Superman and the materials accompanying him acquired the phenomenal qualities enroute. Nevertheless, the costume is impervious to atomic blasts, radiation, bullets, lightning, etc.--truly indestructible and protective. But, for some reason, the costume only functions within the Earth's environment...has problems when cavorting on planets that revolve around a red sun--go figure. The fabric cannot be cut, but I wonder if a laser could disintegrate or separate the Kryptonian fibers? The strength may well be explained by nanotechnology of super strong atoms bound together. Perhaps the fabric is lined with a few atoms thickness of lead for radiation protection. But wait...a new product of fantastic material characteristics--Zylon. Super strong fabric? Tarek Zohdi and George Johnson [UC Berkeley] have teamed with the Boeing company, the Federal Aviation Administration, and the Toyoba Corporation. The new product is supposed to be seven times stronger than Kevlar which is the material used for bullet proof vests. The copy states "...Zylon is woven from yarn consisting of 350 individual polymer microfibers. One square inch of the fabric contains more than 400,000 of those fibers."

Okay, a word or two about Superman's "X-Ray" vision--totally mysterious. The only thing stopping the process is lead, thus the villains are always trying to hide something nefarious behind a lead shield. [Such a feature could well turn Superman into a global pervert checking out women's underpanties and at the same time rendering them sterile.] X-rays do penetrate walls, but even with X-ray vision, Superman would never see what is behind them for two good reasons: X-rays do not reflect very good from objects the way light does for they usually go through until they are absorbed and you only see objects around you when they are illuminated by sunlight or by lamps. This notion of emanation of light [or Superman's "X-Ray" vision] from the eyes is as old as Plato and Euclid. Frankly, the attribution of true "X-Ray" vision for Superman may be a matter of definition and pure science fiction. Maybe Superman has the ability to see through opaque objects by another process unknown to us. "To see through" is the key phrase not really meaning "X-Rays"; that it was a conventional term at the time to associate x-ray characteristics to Superman. Nevertheless, it is cool stuff and I suppose the closest we have come to this phenomena is radar and thermography.

In a broad sense our comic book heroes are just a perpetuation of ancient myths like Hercules or the Golem...and the science is there too.

A recent article from Physics World discusses the possibility of Spiderman-like mobility.

"Physicist Models Spiderman Suit"


Hamish Johnston

August 29th, 2007

Geckos, spiders and the comic-book hero Spiderman seem to defy gravity by scurrying along smooth walls and ceilings. Now, a physicist in Italy claims that humans could soon do the same by donning a sticky "Spiderman suit" woven from carbon nanotubes. Nicola Pugno of the Politecnico di Torino in Italy has calculated that -- assuming the material could actually be made -- a person wearing the suit would be able to cling safely to smooth surfaces such as the side of a skyscraper (J. Phys.: Condens. Matter 19 395001).

The stickiness of geckos and spiders comes from thousands of tiny fibres on their feet that grab hold using a combination of three effects – capillary forces arising from a thin layer of liquid water between the fibres and the surface; van der Waals attraction between the fibres' molecules and those on the surface; and Velcro-like interlocking of the fibres with tiny structures on the surface. Unlike glue, these effects still allow the feet to easily detach from the surface and thus allow the creatures to walk, and they also seem to prevent the feet from accumulating dirt.

Pugno claims that gloves and boots for humans employing the same effects could be made by weaving millions of carbon nanotubes – which are each only about 10 nm thick – into threads about 1 cm thick. The thickness of the individual nanotubes and their spacing could be chosen to make the thread transparent to visible light, which Pugno claims would make them invisible.

The nanotubes at the end of a thread would be splayed in a fan-like structure, which would ensure that there were millions of contact points between the thread and a surface in order to maximize its stickiness. Pugno claims that a combination of capillary, van der Waals and mechanical forces would allow one such thread to support the weight of a man (70 kg) and that a pair of gloves covered in them could support over 1000 kg.

Pugno says that the material would be self-cleaning because carbon nanotubes are hydrophobic and therefore shed water, which takes dirt with it. Because adhesion involves million of tiny sticking points – each of which is relatively weak on its own – Pugno believes that the material could be peeled off the surface with a minimum of effort, provided the user was specially trained in the required hand motions.

Pugno even goes so far as to suggest that the material could be made into a sticky and invisible web that could be used to capture villains. Strains on the material caused by a struggling victim would change the material’s optical properties, rendering it visible to an aspiring Spiderman.

Although the idea of a Spiderman suit may seem far fetched, several research groups have already made sticky materials inspired by geckos – using polymer fibres rather than nanotubes. Also, researchers in the US have made fan-like structures from carbon nanotubes, which Pugno believes could be used in his suit.

The Physics of Superheroes


Jim Kakalios

ISBN: 1592401465

From Publishers Weekly:

"This terrific book demonstrates a number of important points. First, a subject that everyone "knows" is difficult and boring can, in the hands of a master teacher, be both exciting and fun. Second, it's a myth that only people particularly adept at mathematics can understand and enjoy physics. Third, superhero comic books have socially redeeming qualities. By combining his love for physics with his love of comic books, University of Minnesota physicist Kakalios has written a book for the general reader covering all of the basic points in a first-level college physics course and is difficult to put down. Among many other things, Kakalios uses the basic laws of physics to "prove" that gravity must have been 15 times greater on Krypton than on Earth; that Spiderman's girlfriend, Gwen Stacy, died because his webbing stopped her too abruptly after she plunged from the George Washington Bridge; and that when the Flash runs, he's surrounded by a pocket of air that enables him to breathe. Kakalios draws on the Atom, Iron Man, X-Men, the Ant-Man and the Hulk, among many others, to cover topics as diverse as electromagnetism, quantum mechanics, string theory and thermodynamics."

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