I'm just reading a book where a CME event is used as the premise (Going Home: Survivalist Series). I tend to agree that it is a bigger doomsday scenario than EMP, therefore a better premise for survivalist fiction than EMP.crazy2medic wrote:Always the subject is about a EMP attack, which would create some serious problems, it would be a minor issue compared to a CME (coronal mass ejection) a EMP would knock electronics as well as damage the electrical grid in a small area, a CME could bathe the planet in enough energy to fry every modern device and take down the electric grid in every country on the planet, effectively taking every modern country back to the 1880s, do some research into the Carrington Event, the last CME past us just outside the distance of the moon!
My undergraduate education was in Electrical Engineering, Physics, and Astrophysics. So I've put a little thought to the EMP theories out there. I have a sneaking suspicion that EMP doomsday scenarios are the conservative version of Global Warming. In other words, a reasonable hypothesis taken to an extreme for political reasons...
With nuclear blast caused EMP, as with Man Caused Global Warming, there are a slew of hypotheses out there ranging from non-event to the end of all human life. The truth is probably somewhere in between, with my view being somewhat closer to the non-event side of the scale. My proposition is that preparation for EMP event is only as important as any other preparation for nuclear attack. The best defense is to avoid the attack in the first place with missile defense, non-proliferation, anti-terrorist action, diplomacy, and perhaps in extreme cases pre-emptive strikes (conventional or otherwise).
My difficulty with the doomsday EMP scenarios is with the assumption of massive disruption of microelectronics, computers, etc. by EMP caused electrical induction. The theory (as I understand it) is that an electromagnetic pulse will induce a current in "exposed" conductors to such a large extent as to cause destruction of the circuit through excessive current. I think people who have some experience with electromagnetic and "radio" theory will find this scenario less plausible, at least on a massive scale.
I don't know exactly what proportion of thermonuclear blast energy takes place in the portion of the electromagnetic spectrum that induces current in electrical conductors, but for sure it is not 100% if even the majority. There is also, heat, light, UV, x-rays, and neutron radiation to mention a few. All of these attenuate as the cube of the distance from the blast unless focused by the ground or other objects in the case of a ground burst.
The EMP scenarios I have heard presume an air burst or near space exoatmospheric burst. In these scenarios the electromagnetic radiation will definitely attenuate exponentially (cubicly/exponent of 3) based on distance from the blast. In the case of light and heat...yes the atmosphere will block even more than in the "radio" spectrum. But the radio spectrum is significantly less energetic than x-rays, light, and heat anyway.
The length of the conductor involved primarily determines how much current is induced by a given frequency magnetic pulse. That is why transformers, motors, antennae, and other long conductors would be more vulnerable. Coils as in motors, generators, and transformers are mechanisms for fitting the longest conductors in the least amount of space. Therefore I DO see the electricity grid as being vulnerable to EMP, but to what extent, I do not know.
What about the multitude of conductors that lie far from the blast, or underground, or in buildings, or metal boxes. The long wavelengths that induce the biggest currents are the most attenuated by non conductive materials. Microelectronics have by definition very short lengths this would tend to limit the amount of current that could be generated in them. On the other hand, they are very small and can only sustain very low currents before being destroyed. However, SEMI-conductors of which transistors are created are just that, SEMI-conductors. They are ALSO good insulators when not "switched" to conductors by application of current to the control material. I'm not convinced that the vast majority of electronics that are not directly connected to the grid or antennae, would have a current induced in them large enough to destroy their function.
