The Physics of Superheroes: Spectacular Second Edition (33 page)

Or possibly even Peter Parker’s weight. Marvel’s writers have suggested that Spidey’s wall-crawling ability is electrostatic in nature—the 2002
Spider-Man
film included a scene showing scores of microscopic barbed fibers sprouting from Peter Parker’s fingers once he had gained his spider-powers. Turns out that both the comic and the movie are on to something. A report from the University of Manchester in England described the development of “gecko tape,” which consists of millions of tiny fibers (the length of each fiber is fifty times shorter than the width of a human hair) that can provide a strong enough attraction to support a Spider-Man action figure from one’s palm. A tape that makes use of the force arising from fluctuating charges can be, in principle, instantly used and reused, unlike a single-application adhesive that requires a curing time. The fibers on the tape must be very small in order to maximize the ratio of surface area to volume, since only the fluctuating excess charges on the surface of the fiber contribute to the attractive force. In order to provide enough force to support a grown person’s weight, the density of microfibers must be very high, to compensate for the extremely weak force of each fiber. Whether these engineering challenges can be resolved remains to be seen. But if “gecko tape” ever becomes as common as Velcro, I, for one, will never wait for the elevator again!

17

SUPERMAN SCHOOLS SPIDER-MAN—
ELECTRICAL CURRENTS

LET’S
NOW TAKE A CLOSER LOOK
at those electric bolts emanating from Electro’s hands. A large enough positive charge can pull electrons from very far away, even through miles of copper wire. The term for the pull exerted on electrons as they move through a wire is “voltage.” Electrons are negatively charged, so a positive voltage pulls them in one direction while a negative voltage repels the electrons in the opposite direction. The “current” expresses the number of electrons moving past a given point in the wire per second.

Imagine a garden hose connected to an outdoor faucet. In this case, the voltage plays the role of the water pressure that pushes the water through the hose. The amount of water that comes out the end in a given time period is the current. The resistance of the hose arises both from kinks in the line and small holes along its length, from which some water can escape before making it to the end. The more defects in the hose, the greater the water pressure needed to maintain the same water flow (current) from the end of the hose. However, a faucet in a sink can have water flowing without a hose connecting the faucet to the drain—similarly, an electrical current can be pushed by a large enough voltage even in the absence of a wire. This is what happens when a spark jumps from your fingertip to the doorknob or from a cloud to the ground during a lightning strike. The greater the distance, the bigger the force needed to pull the charges, as the Coulomb electrostatic-force expression decreases with the square of the separation of the charges. A long garden hose, with various imperfections and holes, will have more resistance to water flowing through it than a similar short segment of hose. This is why you don’t receive a static shock until your fingers are just about to touch the doorknob: Air is a pretty good electrical insulator, and it takes an electric field of more than 12,000 Volts per centimeter before the pull on the electrical charges is sufficient to make them jump the gap. When it does happen, it stings, and it’s why you most definitely do not want to be zapped by Electro’s massive discharges.

Alas, in
Amazing Spider-Man # 9
, where Spidey first tangles with Electro, the basic physics of electrical current flow is mangled. In one scene during their climatic battle, Spider-Man manages to deflect an electrical bolt that Electro has hurled at him by tossing a metal chair over Electro’s head. “Anyone with any knowledge of science knows that anything metal can act like a lightning rod,” Spider-Man lectures Electro, “as this steel chair is doing!” Actually, Spider-Man’s mistaken understanding of how lightning rods function suggests that his allegedly advanced knowledge of science isn’t all it’s cracked up to be. The electrical bolt is shown arcing away from Spider-Man and chasing after the soaring chair—even though the chair is not electrically connected to anything! Why would Electro’s lightning bolt be pulled toward the chair, metal or not, if once it reaches the chair there is nowhere for the electrical current to go?

When you turn on the water in the kitchen sink, the water flows from the tap to the drain, owing to the downward pull of gravity on the water. It’s not that water is attracted to drains—if one were to install a drain on the ceiling above the faucet, the water would not arc upward, compelled to flow into the drain at all costs. When dealing with electrical charges, what gravity is for the water flow, the voltage difference is for the electrical current.

Electrical charge can’t flow if there is no place for it to go. Actually, this is true for our water analogy as well. Want to know how you can overturn a glass of water filled to the brim and manage to not spill a drop? Do it when the glass is underwater! If there is no place for the water in the glass to go, it will stay inside the container.
⁵⁷

The same is true for electricity. Regardless of the magnitude of the net electrical charge an object possesses, it will not discharge if every other object surrounding it has exactly the same charge. Technically, the voltage that pulls or pushes electrical charges around is a measure of the “potential difference,” defined as the difference in potential energy of a charge as it moves from one point to another. This is what makes Electro so dangerous (in addition to his daring fashion sense): He is able to control his potential difference relative to his surroundings at will, so he can decide when and where he will discharge the excess electrical charge he has stored up.

By applying a voltage across a conductor, I raise the potential energy of the electrons within the conductor, just as when lifting a brick over my head I raise its potential energy. The brick keeps this extra potential energy until I release it, at which point the potential energy is converted into kinetic energy and the brick speeds up as it falls. But this conversion cannot take place until I let go of the brick. Similarly, the electrons in a wire speed up and increase their kinetic energy in the form of an electrical current, in response to the voltage applied across the wire—but only if I close the switch in the circuit and the electrons have someplace to go. Just as the raised brick will keep its potential energy indefinitely until I drop it, the electrons cannot speed up in response to an applied voltage if the wire is not electrically connected to anything. Think again of a garden hose connected to a faucet. No matter how much I turn the faucet tap, absolutely no water will flow through the hose if it is completely sealed at the other end. Before any water can flow through the hose (a current) in response to the water pressure (voltage) at the faucet, I have to uncap the end of the hose so that the water can drain out. The technical way of expressing this is to say that in order for an electrical current to flow through a wire, it must be grounded.
⁵⁸
The Earth, or “ground,” is obviously a large object, with many electrical charges; consequently, it can take up extra electrons, or donate electrons to a wire without difficulty. This notion, that in order for a current to flow, it must have someplace of a lower voltage to go, is fairly reasonable, but Spider-Man seems to not have grasped it, while Superman, from his very first adventure, has demonstrated a solid understanding of electrical currents.

In Chapter 1 we mentioned the early exploits of the Man of Steel, as described in
Superman # 1,
before the world at large knew of his existence. In this story, Superman sought to learn the identity of the person bankrolling the Washington lobbyist who was bribing a senator with the goal of embroiling our country in the war in Europe. (Recall that this story occurred in 1939.) The secret employer of Alex Greer, “the slickest lobbyist in Washington,” turns out to be Emil Norville, the munitions magnate (war being good for business, from Norville’s point of view). For some reason, Greer initially refuses to divulge the name of his employer to this strange man wearing a blue-and-red long-underwear ensemble accessorized with a flowing red cape. In Chapter 1, I mentioned that Superman purposely falls from the top of a high building holding Greer, pretending that the fall will kill them both. Prior to this scene, in order to loosen Greer’s tongue, Superman picks him up like a sack of potatoes and leaps atop some high-tension lines, as illustrated in fig. 26. Greer protests that they’ll be electrocuted, but Superman finds the time to give the lobbyist a physics lesson. (Whether this lecture should be considered an additional part of Superman’s efforts to psychologically torment and elicit information from the lobbyist, I leave to the reader to decide.) “No, we won’t,” the Man of Steel explains, since after all, “birds sit on telephone wires and they aren’t electrocuted—not unless they touch a telephone pole and are grounded!”

Superman is exactly right. It is only when you touch a high-voltage wire and simultaneously grab the telephone pole (or touch another wire at a different voltage), and thereby provide a pathway for the current in the wire to flow to the lower voltage, that you have to worry. In this unfortunate situation, the flow of electrons (a current) passes through the conductor—namely, your body—connecting the two points.

The physics of grounding is well understood a thousand years from now, as indicated in “The Secret Origin of Bouncing Boy” in
Adventure # 301
. Chuck Taine became a member of the teen superhero association the Legion of Super-Heroes when he accidentally drank a super-plastic serum and consequently gained the power of “super-bouncing.” Chuck was quite disappointed to be turned down for membership in the Legion, owing to the super-silliness of his power. Yet he made good use of his second chance to impress the Legion, when he managed to subdue a crook whose electrical gloves had stopped the Science Police and Saturn Girl of the Legion. Chuck knew that when he was bouncing and airborne, he could collide with the crook and not fear electrocution, as he was not grounded at the time. Perhaps it is not so surprising that this story correctly illustrates the principle of grounding, as it was written by Jerry Siegel, Superman’s co-creator.

Fig. 26.
A scene from
Superman # 1,
where the defender of truth, justice, and the American Way coerces information from a Washington lobbyist by giving him a “hands-on” demonstration of the principles of electrical grounding.

It seems that Superman could teach a thing or two about currents and grounding to Spider-Man. The “grounding goof-up” in
Amazing Spider-Man # 9
was not a solitary error, sadly, as
Amazing Spider-Man Annual # 1
(Feb. 1964) finds Spidey again facing off against Electro. This time, as an extra precaution, he
deliberately
attaches a wire to his ankle to ensure that he remains electrically grounded at all times! Promise me, Fearless Reader, that when next you fight a supervillain capable of hurling lethal lightning bolts at you, you will avoid a good, solid electrical connection to the ground!

The whole point of a lightning rod is not that it’s made of metal, but that the lightning will strike the tallest feature on the building (the rod), and the electrical current is then carried from the rod by way of a wire safely to ground, thereby avoiding igniting a fire on the roof of the building. Lightning rods can also carry away excess charges in the atmosphere, decreasing the voltage difference and reducing the likelihood that the building will be struck by lightning in the first place. The static shock between your fingertip and the metal doorknob occurs only when your finger is very close to the door, since the shorter the distance, the less resistance the arc has to overcome. Similarly, the lightning bolt is trying to minimize the distance and resistance on its way to electrical ground. This is why you don’t want to stand under a tree during a lightning storm, as you increase the chance that the lightning striking the tall tree will take a detour through your body—when alone in an empty field during a thunderstorm, one should lie flat on the ground in order to decrease the chance of being struck by lightning. If a building’s lightning rod is not connected to ground, any electrical current entering the rod will find a higher resistance pathway to ground, through the roof and building, with concomitant damage to the structure.

Just such damage will surely be Spider-Man’s fate when he intentionally connects himself to ground, thereby guaranteeing that all of Electro’s electrical energy will pass through his body on its way to a lower potential state. Spider-Man’s “spider-strength” will enable him to withstand some of the damage of the electrical strike, but grounding himself as he does makes the situation much worse than it needs to be.

It’s not clear which of Spider-Man’s co-creators, writer Stan Lee or artist Steve Ditko, should get the blame for these goofs. This ambiguity stems from the “Marvel method” of producing comic books in the 1960s. At Marvel’s Devilish Competitors (as Lee would jokingly refer to DC Comics), a comic-book writer would generate a full script that detailed not only the captions and dialogue and thought balloons in each panel, but also what the artwork in each panel should look like. An editor would then go over the script, making changes as needed, and pass it along to the artist, who would draw the comic story as described in the script. The artwork would then be inked, colored, and lettered, using the dialogue and captions in the script, and the writer would commonly not see the story again until it was available for sale on newsstands. This system works fine as long as one has enough writers and editors to cover the number of comics produced per month, but at Marvel in the early 1960s, the number of writers and editors was low—namely one: Stan Lee. Lee was both the editor and writer of (in 1965, to pick a particular year) the
Fantastic Four
;
Spider-Man
;
The X-Men
;
The Avengers
; Captain America and Iron Man stories (both in
Tales of Suspense
); Dr. Strange, solo Human Torch stories, and Nick Fury, Agent of S.H.I.E.L.D.
⁵⁹
(in
Strange Tales
); Giant Man, the Sub Mariner, and the Incredible Hulk (in
Tales to Astonish
);
Daredevil
; and
Sgt. Fury and His Howling Commandos
(a World War II comic). If the stories in the Marvel universe had a coherent structure and feel, this was no doubt due to the fact that there was a single creative voice guiding the varied comic books.