Analog Science Fiction And Fact - June 2014 (27 page)

If there is a war on science, I don't think popcorn science is its theater
³
.
Analog
sometimes prints science articles as companions to a story, as well as the Science-Behind-the-Story tie-ins on its website. Think of popcorn science as shuffling the pages of these together.

Popcorn science may cross blurry borders into heretical hinterlands, but that's not necessarily bad. As Arlan Andrews puts it, "Reality is a lot broader than we have been taught." If that were not true, there would be no such thing as discoveries, would there?

Personally, I consider popcorn science a guilty pleasure that lets me have my cake (science) and eat it (things blow up) with a slightly positive education value. More importantly, it may inspire the next wave of scientists who might actually have to stave off Doomsday.

1 How's that for a tri-oxymoron?

2 Penned into existence by none other than Abraham Lincoln—you can look that up on the Internet!

3 Is it really obligatory to note whether a pun is intended?

PAST MASTER OF ELECTROMAGNETISM

In an episode of the original
Star Trek
("The Ultimate Computer"), Captain Kirk quotes a line from a poem: "(A)ll I ask is a tall ship and a star to steer her by." It's from "Sea Fever" by John Masefield, first published in 1902. Kirk goes on to say, "You could feel the wind at your back in those days, the sounds of the sea beneath you." Now, I don't know about you, but something about that line and Kirk's comment sings to a longing in my soul. It is a longing born not out of my past or my memories— I have never sailed on a tall ship—but purely from my imagination.

That's probably for the best. For all I know, on a real sailing ship I might spend the entire time seasick, hanging over the rail and vomiting my guts out. I'm a fan of central heating, I appreciate modern plumbing, and for me nothing would kill the romance of the high seas more than the inevitable long hours of boredom on a merchant sailing vessel. Imagination lets us cherry pick the parts we find appealing, and if it didn't there'd be no such thing as fiction.

Wistful thoughts about imaginary maritime adventures have a wide appeal, but my guess is that most
Analog
readers have a few idiosyncratic interests, underrepresented in the general population. Technogeekazoid that I am, one interest that makes me pine for an imagined past is the experimental work done in electrical science back at the turn of the previous century, 1900 through WWI. That's the era of Tesla and Marconi and Edison, something of a subgenre in the Steampunk world, and I like that just fine. But what I'm talking about was largely confined to university labs, where battles were waged on benches with wound wire coils and magnets and primitive electronic test equipment, and dispatches from the front were limited to the physics journals of the day.

What prompted me to write this column was my stumbling upon an online article at
phys.org
called "Manipulating electron spin mechanically." The piece itself was no great shakes and described an experiment wherein electrons were prompted to flip their spins via high frequency mechanical vibrations rather than the usual magnetic fields. I was annoyed because it seemed clear to me that the author thought "mechanical means" were previously unheard of, and I happened to know of one discovered a century ago.

You've probably never heard of Samuel Jackson Barnett, or of the effect that bears his name. Wikipedia has only a few lines about him (14% of which inform us that when he died, it was a month after his wife did), but it does link to their "Barnett Effect" entry, which is also only a few lines. You may have heard of the Einstein-de Haas Effect (which in fairness should be called the Richardson Effect, after Owen Richardson who suggested it first in 1907), likely only because Einstein was associated with it (and this may be the only experiment Einstein himself participated in).

Take a cylinder of, say, iron, and suspend it on its long axis so it is free to rotate inside a coil of wire. Run current through the wire and this will put the iron cylinder in a magnetic field. The field will induce the spins of the electrons (because electrons are little magnets themselves) in the iron to line up. Since electrons have angular momentum, lining them up a bit with a magnet will cause the iron cylinder to rotate. That's the Einstein-de Haas Effect, first demonstrated in 1915. The Barnett Effect is the converse of this. Take that cylinder of iron and spin it on its axis, and it will spontaneously magnetize. The amount of magnetization depends on the rate of rotation and something called the gyromagnetic ratio, which varies from one substance to another and is just one of those values condensed matter physicists measure. Barnett demonstrated this effect in 1914.

So there you have it: a mechanical method to manipulate electron spins (though not a spin-flipper) first found a hundred years ago.

I first heard of Barnett while working on the Marinov motor stuff (see my columns from February and April 1999 and June 2008), while interacting with others who played with magnets and wire in their home shops. A few years later, while consulting, I often combed through old physics journals looking for geeky stuff. A lot of Barnett's papers made the trek to the copy machine. I delighted in reading about what he and his contemporaries researched, and even more about
how
they did it. Oh, to inhabit those laboratories myself! I wish I'd read his papers a few years sooner. One thing that helped immeasurably in the Marinov motor work was my decision to suspend the armature from the ceiling and stop trying to support it from below. This went from being my
eureka!
moment to the "oh, duh" kind when I found out Barnett had relied on suspending similar dinguses a century before.

As I read through some of Barnett's papers (and as I reread them recently), I couldn't help but sympathize and identify with him as he dealt with some who disagreed with the results of his work. A fine scientist, he didn't object to being shown if he was mistaken. But I detected an all too familiar sense of weariness in his written tone as he replied to spurious complaints hatched from experiment-inexperienced minds.

You see, for a while Barnett was involved on one side of the "moving magnetic field lines" controversy as it applied to spinning magnets, and Earle Hesse Kennard on the other. (They were not the only ones.) Barnett was an experienced experimentalist when their disagreements began, and Kennard had yet to receive his doctorate in theoretical physics. (Kennard went on to enjoy a fairly distinguished career, good enough for
two
short paragraphs on Wikipedia.)

I need you to picture an ordinary bar magnet, north pole up. Now picture the magnetic field lines of the magnet, by convention emerging from the N pole and reentering at the S pole. Move the magnet from left to right. What do the field lines do? Historically, and certainly in Barnett's time, that the field lines move with the magnet has been the conventional understanding.

Now imagine a dozen or so bar magnets, attached and evenly spaced, all pointing north pole up, to the rim of a horizontal bicycle wheel, and let the wheel rotate. Again, these are just magnets moving along as in the first case, so there's every reason to think the field lines move with the individual magnets.

Finally, imagine cramming the entire region of the wheel from axis to rim with more magnets until you have the equivalent of a single short, cylindrical magnet, and let it spin. Do the field lines still move with the magnets (or composite magnet)? Barnett and others said yes. I say yes. Kennard and others said no, and it was this dispute among the leaders in the field of electromagnetism that is known as the moving magnetic field lines question.

As it turns out, it is not at all easy to design, let alone perform, an experimental test that will demonstrate once and for all whether or not the field lines move. Most methods tried relied on the fact that an electromotive force (EMF) is generated in a wire moving perpendicularly through a magnetic field, and likewise in a stationary wire when the field is moving. Unfortunately, with a spinning magnet the EMF produced is very weak to begin with, and when you add up all of the EMFs produced in each part of a closed circuit (that is, when you integrate around the closed circuit), you get a big fat zero. A lot of paper was stained with ink in the journals of that day, debating whether or not a particular experimental method predicted a net EMF of zero in both the moving and the stationary field line cases.

A full discussion of the moving lines controversy would fill a book (which I may write) and is outside the scope of this essay. But a specific example of the sort of weary reply Barnett would offer to Kennard that drew me to him is this one from
The Physical Review
back in 1913 (Vol. II, No. 4), in a piece called "On Electromagnetic Induction."

"The brief statement of fact, without reference to authority, in my first paper drew from Mr. Kennard the criticism to which he refers. He said that I had failed to give experimental proof of my statement. References to the experimental work having been given later, however, Mr. Kennard now objects to the experiments of Blondlot, Wilson, and myself on insulators on account of sliding contacts, stationary connecting wires, absence of a conducting screen, etc. These objections are entirely inconsequential and irrelevant and I shall not consider them further. No one will object to the repetition of any or all of these experiments, either modified or unmodified, by anyone who is sufficiently interested in them; but it is quite certain what the results will be."

At the start of this paper, Barnett said it would be his final reply, and you can see why. Kennard had originally accused him of making things up. Then, after references were provided, this kid
theorist
Kennard, unskilled in the craft himself, dumps on the experimental tricks of the trade in common usage by the boys who call the laboratory home. How annoyed
I
used to get when the armchair experimenter set would offer up criticisms to my Marinov motor work, which were "entirely inconsequential and irrelevant." Sam Barnett, I feel your pain.

It really is a shame Barnett has been largely forgotten. For reasons I do not fully understand, sometimes fields of research that once owned the mainstream end up as backwaters. Then people forget those valuable aspects and unsettled questions that put it in the mainstream in the first place.

There is a poignant passage relevant to this in another of Barnett's papers, this from the February 1937 edition of
The American Physics Teacher,
called "Models to Illustrate Gyromagnetic and Electron-Inertia Effects." Therein Barnett discusses experiments performed both by him and others, and also describes tabletop gyroscopic gizmos he employed to explain the nature of magnetic physics at the molecular scale to students. In the first paragraph he laments: "Although these experiments were first made and described over twenty years ago, most teachers of elementary physics in this country seem entirely unacquainted with them; and only a few of our elementary textbooks on physics... mention them."

Though he would live almost twenty more years and die at the age of 83 in 1956, his brand of physics, like the age of sailing ships, never came back into vogue. By then all the attention belonged to quantum mechanics and nuclear physics and relativity and research performed at large facilities by hundreds of people wearing rubber gloves.

As for me, and I'm sure Barnett felt the same, I prefer small labs and dirty fingers, quiet hours to toil in solitude,
and all I ask is a strong magnet and a line to suspend her by.

Next month, our double issue kicks off with an extra-length "Journeyman" tale that follows immediately on the heels of the one in this very issue. In "The Journeyman: Against the Green," Teodorq and his companion Sammi find their current lifestyle under threat, but might that threat also put them one step closer to fulfilling their oath to find the star men?

Then "Journeyman" author Michael F. Flynn doffs his "Science fiction writer" hat and dons one that boldly says "Statistician!" on the brim, when he brings us a larger-than-usual fact article about a subject relevant to every
other
fact article, "Spanking Bad Data Won't Make Them Behave."

In the rest of the issue: someone is hunting cyber-urchins in Juliette Wade's "Mind Locker"; Bill Johnson's "Code Blue Love" brings new meaning to the term "interior monolog"; a journalist is pressed to solve an unusual murder mystery in "Who Killed Bonnie's Brain?" by Dan Hatch; Paula S. Jordan lets us get up close and personal with an alien in "Voorh"; and Rajnar Vajra brings us a modern throwback to the Golden Age with "The Triple Sun."

We even manage to fit in a special feature on foreshadowing by Richard A. Lovett, as well as all our usual excellent columns, and plenty of short stories by exciting newcomers to
Analog
like Timons Esaias's "Sadness"; James K. Isaac's "Valued Employee"; R. Garrett Wilson's "Journeyer"; Eric Choi's "Crimson Sky"; Andrew Reid's "The Half-Toe Bar"; and Alvaro Zinos-Amaro's "Hot and Cold." See you next time!

All contents subject to change

Artificial intelligence (hereafter AI) has been a theme in philosophy and literature since long before science fiction existed. Legends of automatons appear in Greek mythology (the bronze giant Talos who defended the island of Crete, the moving statues of Daedalus), ancient Chinese myth (a life-size human figure made of leather and wood by Yan Shi), and Jewish legend (where King Solomon was said to have designed artificial birds and lions to attend upon him). Al Jazari's
Book of Knowledge of Ingenious Mechanical Devices,
c. 1200 CE, described a boat with four programmable artificial musicians. Leonardo da Vinci sketched a design for a mechanical knight around 1500 CE.