Category Archives: Electromagnetism

The Physics of Nonphysical Systems

We just heard Steinn Sigurðsson complain that there’s no science in Harry Potter, and therefore the book title The Science of Harry Potter is a non-starter. Jennifer Ouellette then leaped to its defense:

I think in this instance, I’d conjure the spirit of Arthur C. Clarke: “Any sufficiently advanced technology is indistinguishable from magic.” :)

But then, that’s just the sort of viewpoint you’d expect from somone who wrote about the physics of the Buffyverse.

In a display of the kind of synchronicity one might expect whenever the system is large and the selection criteria are loose, Bee at Backreaction just pointed to a new paper on the arXiv, “Hollywood Blockbusters: Unlimited Fun but Limited Science Literacy” (9 July 2007). C.J. Efthimiou and R.A. Llewellyn declare their intentions as follows:

In this article, we examine specific scenes from popular action and sci-fi movies and show how they blatantly break the laws of physics, all in the name of entertainment, but coincidentally contributing to science illiteracy.

Movies under their microscope include Speed (1994), where projectile motion is thrown out the window; Spiderman (2002), which stretches Newton past the breaking point; Aeon Flux (2005), whose muscles really have to torque; The Core (2003), which just doesn’t float at all; Superman (1978), which ought to make a physicist’s head spin; X-Men: The Last Stand (2006), whose finale is cut loose from reality; and The Chronicles of Riddick (2004), which I haven’t seen.
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Shopping Cart EMP

It’s our weapon against the commercial machines:

Ever noticed a painted yellow line in the parking lot around many supermarkets and retail stores? The magic yellow line emits a signal that causes carts to stop dead in their tracks, preventing carts from leaving the parking lot.

Now you can build your own portable yellow line — with up to a 20 foot range. Need I say more? Hint: it works inside the store.

Somebody going by the handle “Orthonormal Basis of Evil” has posted instructions for building this device to the Web site Instructables. There are eleven steps between the first act of assembly and the assault upon retail America. Most interesting from a math-and-physics standpoint are isolating the locking signal, which requires a Fast Fourier Transform (FFT), and recreating the locking signal, which is a nice exercise in electromagnetism. Essentially, the lesson is that a current in a wire creates a magnetic field, varying the current creates a fluctuating field, and these fluctuations can propagate through space to carry energy and influence electric charges elsewhere, possibly inducing new electric currents following the lead of the first. Here, the transmitting wire is either buried beneath the parking lot or carried on the person, and the “elsewhere” being influenced is inside the locking apparatus of the shopping cart’s front wheel.

(I may be mistaken here, but I think this is actually a case of near-field induction, rather than the typical far-field plane waves one often studies.)

Installing the device on its human user is an exercise in cybernetics, which “Orthonormal Basis of Evil” has chosen to illustrate in a way a little different from the electromagnetism textbooks I grew up with:
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Michael Egnor and Spiritual Pay-Per-View

The weight of evidence, gathered over at least two and a half millennia, indicates that the mind is a product of the brain. Some people find this notion disquieting, and consequently they marshal various arguments to try and dispel the unpleasant conclusion. I haven’t done a quantitative study on which sophistries are the most common, but I have the strong impression that this one is widely used: the soul isn’t “in” the brain, the denier says, any more than television programs are “in” the TV antenna.

This argument would be a whole lot more convincing if damage to different parts of the brain didn’t have different effects, and if imaging of brain activity didn’t show that particular activities and even modes of thought manifest themselves in different, characteristic parts of the nervous system. We’d have to be tuned to a whole premium package of Soul TV channels, each received by its own wet antenna, and each broadcast by its own Ethereal Broadcasting Company — a whole industry of Spiritual Pay-per-View!

The latest devotee of this dubious proposition is — almost inevitably — Michael Egnor.
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Michael Egnor: 2400 Years Behind the Times

BPSDBI nearly sprayed my breakfast across my friend’s new flatscreen monitor when I saw the latest from Michael Egnor:

Clearly the brain, as a material substance, causes movement of the body, which is also a material substance. The links are nerves and muscles. But there is no material link between our ideas and our brains, because ideas aren’t material.

Mr. Spock, are your sensors detecting any signs of intelligent life?
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Dear Michael Shermer: Physics Matters

Dear Gentle Reader: if you have discovered this post by searching for a phrase like “positive thoughts more powerful than negative thoughts,” it is my duty to tell you that no, they aren’t.

I just spotted (via Mind Hacks and my spiffy new RSS reader) Michael Shermer’s article in the June 2007 Scientific American,The (Other) Secret.” While I appreciate anything which applies the cluestick to pseudoscientific bunk, I’m afraid Shermer needs a bit of a refresher course himself. I quote from a little way into the column:

A pantheon of shiny, happy people assures viewers that The Secret is grounded in science: “It has been proven scientifically that a positive thought is hundreds of times more powerful than a negative thought.” No, it hasn’t. “Our physiology creates disease to give us feedback, to let us know we have an imbalanced perspective, and we’re not loving and we’re not grateful.” Those ungrateful cancer patients.

So far, pretty good. We continue:

“You’ve got enough power in your body to illuminate a whole city for nearly a week.” Sure, if you convert your body’s hydrogen into energy through nuclear fission. “Thoughts are sending out that magnetic signal that is drawing the parallel back to you.” But in magnets, opposites attract—positive is attracted to negative.

Aaagh! Double aaagh!
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Wired: Low Voltage

Wow, the hunt for extrasolar planets is really looking up:

NASA’s Terrestrial Planet Finder, or TPF, is already underway. The artist’s rendering shows a traditional telescope on the left — a visible-light chronograph — that will launch in 2016 and pick out likely candidates. An array of infrared telescopes (right) will launch four years later and look for life signatures.

So says a short in today’s Wired magazine by Bruce Gain and Kristen Philipkoski. Unfortunately, it looks like Wired is not fully plugged in. Keith Cowing of NASA Watch wrote well over a year ago,

According to NASA’s FY 2007 budget documentation “The Terrestrial Planet Finding project (TPF) has been deferred indefinitely.” In other words, it is dead. NASA is just afraid to say so.

As of 18 April 2007, the lack of funding means that TPF has no launch date. So, Wired notwithstanding, TPF is grounded. It just couldn’t get past the budgetary resistance.

Every once in a while I get the feeling that reporters can be real dim bulbs, you know?

(Via Steinn Sigurðsson.)

New Scientist, the EmDrive and the Wobosphere

shnood: (roughly) an imposter; a person oblivious to just how trivial or wrong his ideas are.

“Were there any interesting speakers at the conference?”
“No, just a bunch of shnoods.

“The magazine New Scientist loves to feature shnoods on the cover.”

Note: someone who’s utterly contemptible would not be a shnood, but rather a schmuck.

— Scott Aaronson (27 May 2006)

Those of you interested in the way the Wobosphere functions as a disputation arena (“We Can Fact-Check Yo’ Ass!”) may be interested in the following sordid tale of intrigue and skullduggery. I originally wrote most of this last October, in a lengthy comment on David Brin’s blog. The moral of the story, insofar as I can find one, is this: if you say that you can move your car forward by bouncing a soccer ball back and forth inside it fifty thousand times, you’ll get a quizzical look (at best). If you say the same thing but with “microwave photons” instead of soccer balls, you’re reporting on cutting-edge science!

Back in September, New Scientist magazine published an article on the “EmDrive”, a machine purportedly able to propel itself using microwaves bouncing inside a box. Those of us who remember the Dean drive and umpty-ump other wonder machines have no trouble recognizing this as the same old stuff: like all the wonder-powered spacedrives before it, it can only putter forward by violating the conservation of momentum. New Scientist‘s reportage provoked science-fiction writer Greg Egan to write an open letter saying he was “gobsmacked by the level of scientific illiteracy” the magazine showed.

So it goes, as they say on Tralfamadore. Claims of exotic spacedrives fuelled by violations of fundamental physics are, sadly but understandably, about twopence a dozen. The aspect of the affair which Egan found truly disturbing — indeed, reprehensible — was the way New Scientist glibly provided a “news” piece full of pseudoscientific gibberish purely to justify how the EmDrive might work. (Their argument really pushed the limits of the absurd, too: Einstein’s relativity has momentum conservation built into its mathematical structure, so you can’t use relativity jargon like “reference frames” to sidestep the conservation law.)

Egan posted his letter to the moderated Usenet group sci.physics.research, and the physicist John Baez put a copy on the blog he co-hosts, The n-Category Cafe. This spurred enough people to write New Scientist that the magazine opened a blog thread to discuss the issue, opening with a self-exusing note from the editor, Jeremy Webb. (Said note, as far as I can tell, satisfied nobody.)
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