Sometimes even a skeptic like me feels like the universe is trying to tell him something. Today, it was telling me to write about electromagnetism. The subject has come up no fewer than 3 different times today. So today we're going to discuss a bit about electromagnetic radiation, and why it can be a bad thing.
Image: Artistic rendition of magnetic substorms, causing the aurora borealis.
Source: NASA, THEMIS program
Mythbusters on NPR
While catching up on the NPR program Science Friday from last week (one of the many physics podcasts to which I listen these days), I heard the host Ira Flatow interview the stars of Mythbusters. While they discussed many awesome things, one of those things was the myth about using cellphones on airplanes being dangerous, because it is believed the signals they transmit could mess with the functioning of the electrical systems within the plane.
The mythbusters weren't able to actually bust this myth in the air (stupid FAA regulations), but they were able to test it on a plane while it was still grounded. They found that using cellphones didn't interfere in any noticeable way with the electrical equipment on the plane. Studies performed by other organizations have shown sometimes that it does and sometimes that it doesn't, so it's all very questionable.
So that was incident number one ... which, it turned out, would be closely related to incident number two.
Pilots and Radiation
A friend of mine from high school contacted me to ask about a recent question she'd gotten on an examine to become a military pilot. The question was something along the lines of:
A pilot needs to be more concerned than the average non-flying person with which of the following:
alpha raysbeta raysgamma rayscosmic raysNow, let's first break each of these down.
An alpha ray consists of a bunch of alpha particles, which are basically helium nuclei that have had the electrons stripped off. So they're positively charged particles, and fairly massive ones as such things go - two protons and two neutrons.
A beta ray consists of a bunch of beta particles, which are just electrons (or maybe positrons).
A gamma ray consists of electromagnetic radiation, or photons, that have incredibly high energy.
And, finally, a cosmic ray is a stream of high energy particles (usually protons) that are coming from outer space. We are constantly bombarded by these particles, some of which make it through the atmosphere. They're passing through you regularly. In fact, you can even detect them at home, by building your own cosmic ray detector.
It turns out that the answer is cosmic rays. They're high energy and, the higher you go into the atmosphere, you're bombarded by more and more of them. (Although, in fairness, this is probably true for all four forms of radiation. The atmosphere protects us from a lot of radiation from outer space.) I can imagine that you wouldn't really want to run into any of these sorts of radiation, but certainly the cosmic rays would be the most energetic and, as such, probably the most likely to mess up your electrical equipment. Certainly much more dangerous than the cellphones tested on Mythbusters.
Speaking of Myths
And now we get to our third and most unorthodox entry into electromagnetic radiation: Dragons.
Specifically, I came across a posting on the website of science fiction publisher Tor Books, entitled "Here There Be Dragons (with EMP)." The post, as it turns out, is by author C. J. Hill, who has just penned a young adult fantasy novel, Slayers, which features dragons re-emerging from hibernation into the present world.
However, the truly devastating things about these dragons isn't fantasy at all, but rather based upon a scientific principle that could be dangerous to our very way of life ... the ability to generate an electromagnetic pulse. Here is Hill's description from the article:
EMP is a real phenomenon. I won't go into a technical explanation because it involves way more about electrons, gamma rays, and the magnetic field than you want to know. The brief summary is this: if an EMP of enough force happens, it will destroy electronics for miles and miles around. When the U.S. conducted a nuclear test 250 miles above the mid-Pacific Ocean, (called the Starfish Prime test) it caused electrical damage in Hawaii, which was nearly 900 miles away. It knocked out about 300 streetlights, set off numerous burglar alarms and damaged a telephone company microwave link.
If a strong EMP happens in the states, all manner of life could be affected. In the worst case scenario, no one would have power. Most cars wouldn't start. You wouldn't have ways to contact your friends or family because phone systems and the internet would be down. All the money you have in the bank? When the electronic financial records are destroyed, your money could disappear. Commerce would come to a screeching halt. Farmers wouldn't be able to use their machinery to harvest crops. Even things like city water pumps would be affected because they have electronic parts.
One of the things that would generate an EMP is a nuclear bomb, and in fact most apocalyptic films that involve nuclear bombs going off will show them shorting out electrical systems. (This is handled relatively well in the John Travolta/Christian Slater film Broken Arrow, though it's about the only thing handled well in that film.)
What happens in a EMP is that the electromagnetic fields begin fluctuating so rapidly that they cause major voltage surges within electronic systems, causing them to short out. It's often believed that the systems have to be running to be shorted out, but this isn't necessarily the case. While certainly it's easier to short out a system that already has current flowing through it, a powerful enough EMP could induce a high voltage in an inactive circuit and still short it out.
There are ways to shield against the EMPs, such as a Faraday cage - a wire mesh box conceived by Michael Faraday. The EMP causes a current in the wire of the Faraday cage, thus insulating the objects inside the box. This isn't a perfect fix, but it can afford some measures of protection.
Will Hill's protagonists have figured out how to protect their precious electronics??It's great to see a fantasy novel incorporating some real world science, and I hope it'll be handled realistically. If you've read the book, please comment and let us know!
But what is certain is that a cellphone can't create an EMP. Now, I suppose, the Mythbusters just have to get their hands on a dragon.
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