What Is EMP?
- EMP stands for electromagnetic pulse, which is considered a short burst of electromagnetic radiation. This kind of burst can come from a variety of sources, including our own sun, but in this case we’re talking about a pulse from a nuclear detonation that occurs at an extremely high altitude.
- EMPs are rapid, invisible bursts of electromagnetic energy. They occur in nature, most frequently during lightning strikes, and can disrupt or destroy nearby electronics. However, nuclear EMPs can cover an entire continent and cripple tiny circuits inside modern electronics on a massive scale. The power grid, phone and internet lines, and other infrastructure that uses metal is also prone to effects that resemble those of a devastating geomagnetic storm.
When a nuclear explosion occurs in space above a target, three types of electromagnetic pulses follow: E1, E2, and E3. An E1 pulse involves high-energy gamma rays colliding with air molecules nearly 20 miles above, then raining down electrons that get pulled in by Earth’s natural magnetic field. An E2 pulse comes from high-energy neutrons that get fired in every direction, and an E3 pulse occurs due to the size of the nuclear fireball itself affecting the Earth’s magnetic field. As nuclear physicist Dr. Yousaf Butt explains, these pulses affect everything in line of sight of the nuclear blast. For example, a blast at 60 miles up can affect a 700-mile radius on Earth. However, there is a “safe space” that is unaffected by all three pulses almost directly below the blast thanks to the Earth’s magnetic field.
Why altitude is everything
Nuclear detonations that occur dozens or hundreds of miles above Earth could have devastating consequences compared to those that happen on the ground.
At a high elevation, gamma rays can more easily spread out, hitting many upper-atmosphere air molecules over a large area at once. The low density of air allows electrons to move more freely and maximize the intensity of an EMP.
What Can It Do?
EMP bombs do not cause casualties directly. The blast happens much too far away from people. Their power comes from interfering, disrupting, or damaging electronic equipment. That could mean power grids going down, cars and planes losing power, computer systems going berserk, and possibly even losing emergency backup power at facilities like hospitals. It sounds pretty scary, and EMP blasts are a significant threat, but the effects are largely untested and exaggerated through pop culture and inflammatory claims by politicians.