Analog Science Fiction and Fact 01/01/11

by Dell Magazines

  Now let’s assume the rod was approaching P, in motion along its long axis. Again we make our measurement at P at time t, at the instant the position of the rod is the same as in the static case. Now things are a bit different. As in the static case, the contribution from the back had to leave sooner than from the front to arrive at P at the same time. However, with the rod moving, the back end was not where it was in the static case, but farther away from P. Being farther away, the contribution is also smaller. So despite being the same charged rod in the same position in both cases, the motion affects what is measured at P. (The astute reader will have noticed that I ignored the magnetic field associated with moving charges. I ignored it, but I haven’t forgotten it.)

  To finish out this thought experiment, let’s assume the rod is uncharged, but simply massive, and ask what Newton’s gravity law tells us about the forces due to gravity at the point P. Well, it’s much simpler—it doesn’t matter one bit whether or not the rod is moving because Newtonian gravity is instantaneous: the field in both cases will be the same. However, even though the “speed of gravity” hasn’t been definitively measured (see here: http://wugrav.wustl.edu/people/CMW/SpeedofGravity.html), it is generally assumed that it propagates at the speed of light, and I would be shocked if it didn’t. If the speed of gravity is the same as the speed of light (or any other non-infinite speed), then matter in motion must behave at least somewhat analogously to charges in motion, and at minimum, retarded effects must be present.

  Dr. Oleg D. Jefimenko sent me a copy of his latest (and unfortunately, last) book at the very end of 2006, which he had signed and dated on December 28. I read it the first time shortly after it arrived, and knew that eventually I would write about it, either as a straight review or in the context of a larger issue. I didn’t want to discuss it immediately because I had talked quite a bit about Jefimenko in my January/February 2006 Alternate View, “Length Contraction.” A few years later I reread it thinking maybe it was time to write about some of Jefimenko’s recent work, but then the global warming stuff started heating up and I got distracted. I was also faced with the question of just how to approach it. I had already talked enough about retardation, and this book just represented the application of that concept to gravity. That makes almost the entire book an exercise in pure theoretical physics and heavy on the math (even though it’s just vector calculus in retarded form). Some of the implications of the math were fascinating and perfect for a science fiction venue, so I absolutely had to talk about those sometime. But I hoped to do so in the context of “here’s a result found in this book” as opposed to “here’s a book and this is one of the things you’ll find in it.”

  Then fate stepped in and forced the issue. I think Jefimenko’s work on gravity is important enough that it needs wide dissemination, so the sooner after his death I discuss it, the better one’s chances of obtaining his book. I don’t expect it to replace General Relativity; indeed, I think GR is already on the right track. But the fact is that if the speed of gravitational interactions is limited to the speed of light, then in the ordinary cases in which GR reduces to Newtonian gravity, it reduces to Jefimenko’s extension, not Newton’s original.

  Jefimenko’s book, with full title, is Gravitation and Cogravitation: Developing Newton’s Theory of Gravitation to Its Physical and Mathematical Conclusion (ISBN: 0-917406-00-1). It is a continuation of a project begun by Oliver Heaviside in a paper from 1893 called “A Gravitational and Electromagnetic Analogy.” You can find the paper online here at http://www.electretscientific.com/author/heavisid.html. This is an unedited version of the original, except that Jefimenko did us all the favor of having “converted some formulas and all vector equations appearing in the article to modern mathematical notation.”

  On his Electret Scientific Co. author webpage (http://www.electretscientific.com/author/author.html) Jefimenko described his current research interests this way: “I am also working on the generalization of Newton’s gravitational theory to time-dependent systems. By analyzing causal gravitational relations, I find that there is no objective reason for abandoning Newton’s force-field gravitational theory in favor of a metric gravitational theory… ” This is a significant claim, and whether or not it is correct, since we use Newton’s theory all the time, the least we should learn to do is apply it in a way that doesn’t treat gravity as instantaneous. He goes on to say: “I base such an expansion, or generalization, on the existence of the second gravitational force field, the ‘cogravitational, or Heaviside’s, field’ (except for a numerical factor, the cogravitational field is the same as the ‘gravimagnetic’ field of the general relativity theory). This field was first predicted by Oliver Heaviside in his 1893 article ‘A Gravitational and Electromagnetic Analogy.’ ”

  The “gravimagnetic” field is more often called the gravitomagnetic field. It is a force created by moving masses that acts only on other moving masses. I did a quick Google search on the term and it turned up a lot of crap, but this link yields a brief, accurate description: http://www.aip.org/pnu/1996/split/pnu295-2.htm. It says: “A gravitomagnetic field, according to the theory of general relativity, arises from moving matter (matter currents) just as an ordinary magnetic field arises from moving charges (electrical currents).” This is why I said above that I hadn’t forgotten that moving charges create magnetic fields—because moving masses also produce a force analogous to magnetism, in both GR and the generalized Newton’s theory. Wikipedia isn’t always a good source, but for a bit more information, this entry seems okay: http://en.wikipedia.org/wiki/Gravitomagnetism.

  Recall that Jefimenko said there’s “no objective reason for abandoning Newton’s forcefield gravitational theory in favor of a metric gravitational theory… ” If true then in principle experimental results will allow us to discriminate between the two theories, but I’m not holding my breath waiting for that to happen. It’s hard enough just trying to measure the gravitational constant “big G” to high accuracy. And the full theory of generalized gravity predicts several other forces besides the first two (for instance, the “gravikinetic” force, associated with accelerating masses) which makes it even more complicated than it looks at first glance. It will be awhile before we can make predictions numerically accurate enough to check one against the other. That having been said, perhaps we can look to the heavens and see if the generalized theory might explain some phenomena that we as yet don’t understand too well.

  As I skim through the pages I am once again astounded by the number of examples worked out for simple systems moving at ordinary velocities (much less than C), and the implications of them. For instance, the title of chapter 14 is “Torque Exerted by a Moving Mass on a Stationary Mass” and therein Jefimenko applies the generalized theory of gravitation to multiple examples of this phenomenon. Example 14-3, derives the torque for a point mass moving in a circular orbit, analogous to a planet revolving around a star. The result shows that a planet exerts a torque on the star, making it rotate faster in the same sense that the planet is revolving. Since a star is not solid, planets in her equatorial plane would cause the equatorial region to rotate faster than the polar regions. Jefimenko, having “looked to the heavens” before us thinks this effect may explain why the equator of our own Sun rotates faster than at the poles.

  Chapter 7 is called “Differential Equations for Gravitational and Cogravitational Fields; Electromagnetic Analogy.” This chapter shows how very similar the generalized theory of gravitation is to Maxwell’s electromagnetism. Jefimenko puts the value of this as simply as one can: “An important consequence of this similarity is that many methods and techniques originally developed for solving electromagnetic problems can be used for solving problems involving gravitational and cogravitational interactions.” It is not so simple as substituting one Greek letter for another, however. For instance, there is a gravitational induction analogous to electromagnetic induction, but is there anything analogous to assorted magnetic materials? Or dielectrics? Or even an
ordinary conductor, let alone a superconductor? Jefimenko is well aware of this and quite clear that we are speaking of an analog here.

  To even things out, we have chapter 19 called “Gravitation and Antigravitation.” Here we find “gravitational equations depicting ‘nonlinear’ gravitational effects (that) do not have their electromagnetic counterparts.” Unfortunately, though I could hack out a brief description of what’s in the chapter, I can’t do it and have it make sense to you without your first reading the previous 18 chapters. Suffice to say that the generalized theory of gravitation allows for the existence of stellar and intergalactic antigravitational mass configurations. This is not about ordinary matter being put into some magical shape that makes it repel other matter. Rather, it is that the net gravitational field in free (empty) space, like between galaxies, can be repulsive rather than attractive.

  What might we see if we consulted the heavens about that possibility? Cosmic acceleration perhaps?

  Copyright © 2010 Jeffrey D. Kooistra

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  IN TIMES TO COME

  Our March issue features a mix of fiction and fact varied in all ways, from writers old and new, on scales from very large to very small, and in settings from very near to very far. Paul Carlson, who made his debut here a couple of years ago with “Shotgun Seat,” his quietly sneaky tale of robotic revolution, is back with a follow-on called “Rule Book” (but you don’t have to have read the earlier story to enjoy this one). John G. Hemry offers another of his unique variations on time travel; Bud Sparhawk covers everything (and I mean everything) in “Astronomic Distance, Geologic Time”; and Jerry Oltion looks at another way changes in how we live can permeate how we think, feel, and judge.

  Edward M. Lerner’s article “Say What? Language, Communication, and Science Fiction” we’re billing as a science fact article, and it is— but we could just as easily have called it a how-to for science fiction writers. It’s both, and whether you’re interested in language for its own sake, or for how you might use it (or be tripped up by it) in writing your own stories, I think you’ll find it fascinating.

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  THE REFERENCE LIBRARY

  Don Sakers

  Science fiction is unusual among the genres because it routinely appears in all different lengths. This isn’t quite the case with other types of fiction. It’s rare to see romance stories shorter than novella-length; historical fiction and thrillers almost exclusively appear in novel length or longer. Fantasy and mystery short stories do appear, but the dominant form in both genres is the series of novels. Only in science fiction do readers regularly find works of all lengths from the short-short all the way up to the novel series, and everything in between.

  I should pause here for some definitions. Most SF readers are accustomed to a division of short fiction by word counts, as codified in the rules for the Hugo and Nebula Awards. A short story is anything up to 7,500 words; 7,500 to 17,500 is a novelette; 17,500 to 40,000 is a novella; and anything over 40,000 words is a novel. This system, while useful and necessary for the fair administration of awards, leaves something to be desired from a literary criticism standpoint.

  In lit-crit circles, a primary distinction is made between the short story and the novel. A novel generally features many characters and multiple subplots, has a broad range in time and space, and explores the world (or worlds) and culture(s). A short story, by contrast, focuses on a small number of characters (generally three at most) and has at most one subplot, is sharply limited in time and space, and illuminates one aspect of a world or culture.

  A novelette is essentially a long short story, with the same focus and economy; a novella is a short novel, sharing the novel’s broad range only in fewer words.

  This whole scheme is complicated by the economics of publishing. Prior to the mid-1970s, it was uneconomical to publish science fiction books of much over 200 pages (about 60,000 to 70,000 words). Nowadays, the average novel runs between 300 and 400 pages (about 100,000 to 150,000 words) and 500+ pages is not unusual. In today’s terms, most of the classic works of the past—most of books of Poul Anderson, Isaac Asimov, Arthur C. Clarke, Gordon R. Dickson, Robert Heinlein, Ursula LeGuin, Anne McCaffrey, and a hundred others—would be considered novellas. At the time they were published, though, they were full-grown novels one and all.

  I need to make special mention of some length categories that aren’t covered above. If a short story is focused, then a “short-short” is a laser beam, usually clocking in at under 1,000 words and concentrating on one single event or idea: Analog’s “Probability Zero” stories are short-shorts. And the series is definitely a literary form in its own right—I covered the various kinds of series in the June 2010 issue.

  In the beginning, there were only novels. The first recognized short story writers were Edgar Allan Poe and Nathaniel Hawthorne in the 1840s, but short stories didn’t become commercially widespread until the arrival of the pulp magazines in the early 1900s. The ascendancy of Street & Smith Publications in the 1910s brought about the era of genre pulps: magazines dedicated to romance, mysteries, adventure, sports, westerns . . . and, of course, science fiction. (The magazine you’re reading is perhaps the last remaining vestige of that era, having started its life as the pulp Astounding Stories in 1930.) Even in those days, science fiction magazines regularly published novel-length works in serial form.

  World War II paper shortages damaged the pulps—competition from comic books, paperbacks, and television destroyed them. Writers in most other genres moved almost exclusively to novels—but science fiction magazines thrived, and writers continued producing short fiction. Books of short stories appeared, whether single-author collections or multi-author anthologies. Although the magazines faced difficulties (and still do), short fiction remained a perfectly viable length for science fiction . . . as it does even today.

  At the other end of the scale, science fiction novels expanded. The 1960s brought Heinlein’s Stranger in a Strange Land and Herbert’s Dune, both considered exceptionally long novels for the time. Trilogies and longer series proliferated. Science fiction settled into its current range across all lengths of fiction.

  The obvious question is why: what is it about science fiction that allows it to thrive at all lengths? One is tempted to credit tradition, the historical accident of the SF magazines’ survival and their continued outlet for short fiction—but that merely begs the question. Why did SF magazines survive, of all other genres?

  I believe that the true answer lies in the unique nature of science fiction. All fiction is entertainment, but SF aspires also to stimulate the intellect and provoke thought. In the postwar world, comics and television could supply entertainment, but not intelligent thought. Science fiction is, and always has been, primarily a literary form.

  Ideas come in all sizes, short and long, simple and complex, focused and broad. Concerned as it is with ideas, science fiction likewise fits a variety of lengths. That, I believe, is why you’ll find SF in every length from short-short to twenty-volume series.

  Warrior Wisewoman 3

  edited by Roby James

  Norilana, 306 pages, $12.95 (trade paperback)

  ISBN: 978-1-60762-061-7

  Series: Warrior Wisewoman 3

  Genre: Anthology

  I mentioned above that science fiction short stories continue to appear, and not just in the magazines. The anthology of original stories has been a mainstay of science fiction since Frederik Pohl edited the first volume of the Star Science Fiction series in 1953.

  For the third year in a row, editor Roby James has put together an anthology of science fiction stories that feature powerful and remarkable women. These stories are all quite definitely science fiction, and there’s something here to please every taste. Among the standouts ar
e Aimee C. Amodio’s “Tourist Trap,” which describes an alien world with a uniquely dangerous ecosystem; Al Onia’s “The Envoy,” featuring a peacekeeper whose methods are truly unexpected; and “Katyusha’s First Time Out,” a story of a teens rebellion against her mother set in a post-apocalyptic world. “Dark Mirrors” by John Walters turns military science fiction on its head, examining the choices that a woman of conscience must make in the face of war.

  In her introduction, editor James counters a widely-held misconception about the Warrior Wisewoman anthologies: she does not exclusively publish stories by women. In fact, this volume very nearly achieves gender parity: ten of the stories are by women, nine by men.

  If you like good short science fiction, you’ll definitely want to get a copy of Warrior Wisewoman 3.

  After the Sundial

  Vera Nazarian

  Norilana, 222 pages, $9.95 (trade paperback)

  ISBN: 978-1-60762-077-4

  Genre: Single-Author Collection

  Vera Nazarian has become primarily known as a publisher; she’s been making quite a name for herself with Norilana Books, one of the newest and most prolific small presses in SF/fantasy. But Nazarian is also a writer, and a darn good one. Best known for lyrical fantasy such as Lords of the Rainbow and Dreams of the Compass Rose, Nazarian also does science fiction, and After the Sundial is a collection of short stories, poems, and a novella. If there is a common thread among these pieces, it is that each of them deals with time in some fashion.

  “The Ballad of Universal Jack” tells the story of a space-station worker who makes a fundamental discovery about the power of words. In “Mount Dragon” a human helps an ancient intelligence achieve the goal it has forgotten, while “The Ice” concerns an exploration mission crashed on Titan.