Detecting electromagnetic waves created by someone’s thoughts is one thing, but can one work backward to determine the neuronal currents that generated them—that is, can one actually read and interpret someone else’s thoughts? Yes. Prof. X and Saturn Girl presumably do it the same way that “reverse television” functions. Let me explain how this would work.
Television signals consist of electromagnetic waves sent out by a powerful transmitter that, upon striking a rooftop antenna, cause the charges to oscillate back and forth with a frequency and amplitude characteristic of the incident signal. The information encoded within the electromagnetic wave is then sent to the television set. (The following description applies to old style cathode ray tube television sets.) The heart of the set is the picture tube, which consists of a large glass surface onto which is evaporated a phosphorescent material that gives a brief flash of light when struck by an energetic electron. This glass face is one end of an irregularly shaped glass box. At the narrow end of the box is a wire, heated by an electrical current so that electrons are stripped from it. These now free electrons are then directed, by way of metal “steering” plates at suitable voltages, toward the other end of the picture tube—that is, the end having the large face coated with phosphorescent material. By choosing the right voltage on the steering metal plates, the electrons can be directed to strike a particular region of the screen. The interior of the television tube is evacuated, so as to reduce the number of stray air molecules that could cause unwanted scattering of the electron beam. Whenever the beam strikes the screen, depositing its kinetic energy into the phosphor material, it causes a flash of light to be emitted. The voltages applied to the steering plates are then adjusted, and the electron beam is now directed to another location on the screen, lighting another phosphor or leaving it dark if the beam is stopped. This continues until the electron beam has moved across the entire screen. A given array of lit and dark regions across the screen yields an image on the face of the television.
By slightly changing the image being projected onto the screen, the illusion of motion can be induced. If three different phosphors or colored filters emitting red, green, and blue light are used at the spot struck by three electron beams, then slight adjustments as to how much of each filter is illuminated in each location results in a color picture. The basic physics underlying television is that the information encoded in the electromagnetic wave contains a set of instructions for the magnitude and timing of the voltages to be applied to the steering plates.
The varying electron beam in the picture tube gives off its own set of electromagnetic waves, different from the waves that were received by the antenna, but related to the television image. A sensitive antenna placed near this monitor could detect these electromagnetic waves and, with the appropriate software, reconstruct the image that the electron current is intended to create. This “ reverse television” is a very inefficient way to have two sets showing the same image, but it would be one method by which a person could read the information projected onto a computer monitor without directly hacking into the computer.66 Or send information from one brain to another.
What about Prof. X using the power of his mutant mind to control the actions of someone else? Recent experiments suggest that this situation may not be so far-fetched. It has been demonstrated that not only can we detect the weak magnetic fields created by ionic currents in the brain, but that the reverse process is also possible. Neuroscientists have developed a research tool called transcranial magnetic stimulation (TMS). In this procedure, a randomly varying magnetic field is applied to a human test subject’s head, providing electrical stimulation to selected regions of the cerebral cortex. The subject’s reaction time and ability to initiate a voluntary hand movement are disrupted by the application of the external magnetic field.
The ability to control the actions of others, using just the power of one’s mind, is not limited to mutants and heroes from Saturn’s moon Titan. In fact, I have been known to demonstrate just such amazing mental powers. Often my lectures can induce my students to either exit the lecture hall at a great speed or to fall into a deep and profound slumber!
SECTION 3
MODERN PHYSICS
21
JOURNEY INTO THE MICROVERSE—ATOMIC PHYSICS
COMIC-BOOK READERS HAVE a reasonable expectation that the hero will triumph by the end of the story. The fun, therefore, lies in the challenges that must be overcome as each month’s tale races toward its conclusion. Not to put too fine a point on it, but the better the supervillain, the better the story—which is probably one reason the Fantastic Four was such a popular comic book in the early sixties. Certainly, the artwork by Jack Kirby was a major factor, as was Stan Lee’s plotting and characterization of the intrepid quartet. But if a superhero is only as good as his or her nemesis, then the Fantastic Four achieved greatness in issue # 5 (July 1962) when they became “Prisoners of Doctor Doom.”
Victor von Doom was a scientific genius, second only to Reed Richards, the leader of the Fantastic Four. Richards and von Doom attended the same college, both on “science scholarships” (in the fantasy world of comic books, institutions of higher learning compete for academic scholars the way our real-world universities vie for athletes). Von Doom was expelled when one of his “forbidden” scientific experiments went disastrously awry, blowing up the lab and scarring his face. Hiding his disfigurement behind a metal faceplate, he designed a high-tech suit of armor that rivaled Iron Man’s and began a long campaign of world conquest as Doctor Doom. Of course, not having finished his degree, von Doom is not really a doctor, and it is most likely his bitterness about his A.B.D.67 status, along with his desire to humiliate Reed Richards, that drives his evil ambitions. Unlike the villains in DC stories in the 1960s, who would inevitably be captured and turned over to the police at story’s end, the Fantastic Four never seemed to be able to battle Doctor Doom to better than a draw. Of course, because Doom was the dictatorial ruler of the small European nation of Latveria, it was always a bit vague as to who the proper authorities were that one could hand an evil head of state over to.
More to the point, Doom’s pride was so great that he would rather face near-certain death than incarceration. Consequently, a typical battle with Doctor Doom would end with Doom being lost in space, or marooned in another dimension, or trapped in time—all fates he had intended for the Fantastic Four. At the climax of the aptly titled “The Return of Doctor Doom” in Fantastic Four # 10, Doom was struck by a reducing ray he had planned to use on the Fantastic Four. The story ended with Doom shrinking to noth ingness, but this would not be the last we would see of him. Six issues later in Fantastic Four # 16, the Fantastic Four journeyed to “The Micro-World of Doctor Doom,” where they learned that Doom had survived his shrinking ordeal. At some point in his reduction, Doom entered a “micro-world—a world that might fit on the head of a pin.” Later, in Fantastic Four # 76, Reed, Ben, and Johnny ventured into an entire microverse, that is, a universe (or at least a galaxy) of micro-worlds. The microverse was depicted as residing within a stain on a microscope slide in Reed Richards’ laboratory. This, at least, removed the need to explain the enormous coincidence in Fantastic Four # 16 of Doctor Doom and the FF standing exactly above one such micro-world just as they began to shrink.
If the micro-world that Doom encountered and subsequently conquered could indeed fit on the head of a pin, then its diameter at the equator is approximately 1 millimeter. For comparison, the Earth’s diameter is thirteen thousand kilometers. One kilometer is one million millimeters long, so the micro-world is thirteen billion times smaller than the Earth. Recall that in Chapter 5 we discussed the difficulties involved in reducing an object in size. The micro-world cannot be six billion times denser than our planet, unless it is composed of white-dwarf-star matter. The fact that Doctor Doom, the Fantastic Four, and the inhabitants of this micro-world are able to walk around normally suggests that this is not the case. Both Doctor Doom and Reed Richa
rds seem as smart on the micro-world as they do at their normal size, and the Thing is not any less strong, so it is unlikely that atoms are removed from them upon shrinking. We must therefore regretfully conclude that the micro-world of Doctor Doom is much like his other “master plans”—impressive in principle but lacking in execution.
If it’s that hard to construct a world to fit on the head of a pin, what are we to make of the Atom’s adventure with “The Deadly Diamonds of Doom” in Atom # 5? In this story, a diamond artifact found on Mount Pico in the Azure Islands is brought back to Ivy Town by an archeologist friend of Ray Palmer (alter ego of the Atom), whereupon a strange ray beam emanates from it, turning people and house cats into diamond statues. “Even though it appears solid” thinks Professor Palmer as he reaches for his size and weight controls, “there are vast gulfs of space between the atoms that comprise the diamond!”
True enough. Most of an atom is indeed empty space between the positively charged nucleus and the average location of the negatively charged electrons. As the Tiny Titan shrinks down to subatomic length scales, he discovers an entire other planet, inside an atom! I’m at a loss to suggest what this other planet could be composed of. It certainly can’t be made of atoms, since it is smaller than the electrons that reside in the diamond artifact. Certainly the discovery that there could be entire civilizations residing within the atoms of ordinary matter would garner Palmer a Nobel Prize, at the very least, along with worldwide fame and fortune. Such is the hallmark of this hero that he never even considers reporting this scientific discovery, nor any of the other micro-worlds he encounters in Atom # 4, # 19, the Justice League of America # 18, or Brave and the Bold # 53.
While comic-book claims that there are micro-worlds within atoms is pure fantasy, the region within an atom as elucidated by quantum mechanics is no less strange. Within the “empty spaces” inside an atom are the “ matter-waves” associated with an electron’s motion. These matter-waves are the key to understanding atomic physics.
WHAT DO YOU DO WHEN EVERYTHING YOU KNOW IS WRONG?
It is now time for us to delve into the world of atoms. Things will get physics-y here for a few pages, but bear with me. We’ll get back to comic books soon enough, but some background is needed in order to understand why at least some physicists take the notion of parallel universes and an infinite number of Earths seriously.
At the end of the nineteenth century, there was a growing body of experimental evidence that indicated that the physical principles described in the preceding chapters failed at explaining the behavior of atoms and light. For example, physicists were stymied trying to explain why hot things glowed. Place an iron poker in a roaring fireplace and, as it warms, it initially glows red and eventually gives off white light. Thanks to Maxwell’s theory of electromagnetism discussed in the previous chapter, physicists understood that the oscillating electric charges in each atom, shaking back and forth as the poker became hotter, emitted light, and that the faster the atoms shook back and forth, the higher the frequency would be of the resulting electromagnetic radiation. Back in the 1800s, scientists had devised very clever techniques for measuring both ultraviolet and infrared light, which are at the upper and lower ends of the visible electromagnetic spectrum, bracketing the narrow slice of light that our eyes can see. Consequently, they could accurately measure exactly how much light a hot object emitted at any given wavelength as its temperature was increased. They discovered two surprising things. First, the fraction of light emitted at a specific wavelength depends only on the temperature of the object, and not on any other characteristic. Regardless of an object’s material composition, shape, or size, the only thing that determined the spectrum of light emitted was its temperature. Second, the total amount of light emitted was not infinite and also depended only on the temperature. This second point was the first falling domino that ultimately led to the development of quantum mechanics.
The fact that the light from a hot object depends only on its temperature prevents us from getting something for nothing. If two objects made of different materials at the same temperature emitted different radiation spectra, there would be a way to have a net transfer of energy between them and hence useful work, without any heat flow. While this would be a convenient violation of the second law of thermodynamics, it turns out that this does not occur for just that reason. A practical benefit of the fact that the emitted light spectrum depends only on the temperature is that we can use the intensity of emitted light as a function of wavelength to determine the temperature of objects for which normal thermometers are useless. This is how the surface temperature of the sun (roughly 11,000 degrees Fahrenheit) and the background microwave radiation remnants of the Big Bang (3 degrees above absolute zero) are measured—through observations of the spectrum of light they produce.
The second discovery, that the energy emitted by a glowing object is not infinite, was not really a shock to physicists. What they found disturbing was that Maxwell’s electromagnetic theory predicted that the amount of light energy emitted should increase without limit! Calculations using Maxwell’s theory correctly predicted how much light would be emitted at low frequencies, in exact agreement with observations. As the frequency of light emitted by a hot object increased into the ultraviolet portion of the spectrum, the measured light intensity reached a peak, and at higher frequencies decreased again back to a low value, which is what one would expect from both conservation of energy and common sense. However, the curve calculated from Maxwell’s equations and thermodynamics indicated that the intensity would become infinitely high for light above the visible portion of the spectrum. This was labeled the “ultraviolet catastrophe,” though it was only a “catastrophe” for the theorists doing the calculations. Many scientists checked and rechecked the calculations, but they could find nothing wrong with the math. Apparently, there was something wrong—or rather, incomplete—with the physics.
Maxwell’s equations had worked so well in all other cases (they led to the invention of radio in 1895 and would eventually enable the development of television as well as all forms of wireless communication), that it was doubtful that there was something fatally wrong with them. Rather, scientists concluded that the problem must lie with applying Maxwell’s theory to the shaking atoms in a glowing object. Again, many tried to find an alternative approach, some different theory that could account for the observed spectrum of light emitted by a glowing object. Here is where the fact that the spectrum depends only on the temperature of the object becomes important. If the theory of electromagnetism could not account for the behavior of one or two exotic pieces of matter, well, that would be somewhat awkward, but not earthshaking. The inability to explain a property shared by all matter was downright embarrassing, and something had to be done.
In 1900 the theoretical physicist Max Planck, recognizing that desperate times called for desperate measures, did the only thing he could to explain the spectrum of light emitted by a glowing body: He cheated. He first determined the mathematical expression that corresponded to the experimentally obtained glow curve. Once he knew what formula he needed, he then set out to find a physical justification for it. After trying various schemes, the only solution he could come up with that gave him the needed glow-curve formula involved placing restrictions on the energy of the atoms that made up the glowing object. Planck essentially proposed that the electrons in any atom could only have specific energies. From the Latin word for “how much,” this theory was called “quantum physics.” The separation between adjacent energy levels was in practice very small. And I mean really small: If the energy of a well-hit tennis ball is 50 kg-meter2/sec2, then the separation between adjacent energy levels in an atom is less than a millionth trillionth of a kg-meter2/sec2. This should provide some perspective the next time you hear a commercial boasting that the latest innovation in an automobile design or a laundry detergent represents a “quantum leap.”
Planck had to introduce a new constant into his calculations,
an adjustable parameter that he labeled “h.” He assumed that any change in the energy of an atom could only take on values E = hf, or E = 2hf or E = 3hf, and so on, but nothing in between (so the atom could never have an energy change, say, of E = 1.6hf or 17.9hf), where f is the frequency characteristic to the specific atomic element. This is like saying that a pendulum can swing with a period of one second or ten seconds to complete a cycle, but that it was impossible to make the pendulum swing back and forth in five seconds. Planck himself thought this odd, but found it necessary in order to make his calculations come out right. He intended to let the value of h become zero once he obtained the correct expression for the spectrum for a glowing object. To his dismay, he discovered that when he did this, his mathematical expression went back to the infinite energy result from classical electromagnetism. The only way to avoid this nonsensical infinite result is to say something equally nonsensical (at least to scientists at the time), that the atoms cannot take on any energy value they want, but must always make changes in discrete steps of magnitude E = hf. Since h is very, very small (h = 660 trillion trillion trillionths of a kg-meter2/sec), we never notice this “graininess” of energy when we deal with large objects such as baseballs or moving automobiles. For the energy scale of an electron in an atom, it is quite significant and absolutely cannot be ignored.
The Physics of Superheroes: Spectacular Second Edition Page 27
