Monday, 20 July 2009

Update on the Apocalypse

This update is just really to explain why I wrote the previous post (apart from the fact that I enjoy such little scratch calculations), about EMP attack concerns, how it fits in with my general theme of scepticism. It is in a new post as it got a bit long.

Dr Forstchen’s PhD is not in any science. He is a professor of history (lecturer as we might say in the UK, I don’t know if he is as senior as what we would call a professor) and an author. He has researched this topic for several years according to the potted biography in the article for his book “One Second After”. Apparently the book has been cited in US Congress as a realistic portrayal of the after-effects of an EMP weapon.

Yet not only do I think he got the magnitude of the effect wrong, in the article he makes basic errors, some of which I identify below.

This article is more hype than science, like most catastrophism including more popular recent themes like global warming and population catastrophe. It is a man who has no doubts, and I suspect has hunted out evidence for a catastrophe he knows is going to happen, rather than first questioning whether it could happen.

It took me maybe 20 minutes to come up with a realistic mean energy density in Dr Forstchen’s scenario, yet in his four years of research he appears not to have tried to find out how power is defined and measured, let alone checked that a nuclear detonation from a third-world bomb would have the energy to do the damage he claims.

He compares the production of EMP to a pebble rolling, hitting a larger one, in turn starting off larger ones to start an avalanche. That is a ridiculous analogy, even ignoring the fact that an avalanche is snow. If a pebble starts a rock fall or land slip the energy comes from the act of gravity on each rock, it is not all contained in the original pebble. No source of energy for the EMP other than the nuclear explosion is suggested.

He talks about “… power that could range up to hundreds of amps per square yard …” but not only are amps per square yard not a measure of power, it is a largely meaningless measure. It certainly will not tell you that damage will be caused to anything but sensitive, unshielded electronics. Even then a lot more needs explaining as to what medium these large currents are running in, because given the same EMP a much higher current will be produced in metal than in topsoil, let alone rock or concrete.

“a high tension wire miles long will absorb tens of thousands of amps”, but cables don’t absorb current, they transmit it. Again a meaningless statement.

“All electricity travels, of course, at the speed of light”, no it doesn’t. I remember at university calculating the speed of a wave in a co-axial cable. That did turn out to be c, the speed of light in free space. In other media it travels at different speeds, and speed can depend on frequency of AC, which an EMP would produce.

I am not sure how “hundreds of amps per square yard … will not affect you directly, at most you'll feel a slight tingling …”. Let us say a large person is facing the current direction, sectional area maybe a square yard. They have hundreds of amps flowing through them! I am not sure how the good professor ever thought that something that fried all electronics, even the shielded ones in a car or an electrical substation 1500 miles away, wouldn’t hurt at least some of the people 300 miles below, who were receiving 25 times the power.

“Commercial airliners today are all computer driven … When the pilot pulls back on the "stick" it is no longer connect by wires stretching all the way back to the tail and the elevator assembly. Instead, his motion is read by a computer which sends a signal to an electrical servo - motor in the tail, which then moves the tail” would surprise Boeing, and in fact all Boeing pilots, many of whom like the fact that they are not fly-by-wire. Of course no commercial airliner has controls connected by wire, or has for decades. This man is a pilot, and doesn’t know that?

By the way I reckon some aircraft might have a problem. However I have flown through storms, and been hit by lightning and not even known until the engineer identified the notch on the flap as lightning damage. Metal, as Dr Forstchen says, takes most of the current. The present generation of passenger aircraft are still primarily made of metal. That generally protects the electronics, and would certainly provide some cover from an EMP.

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