MrSeb writes: "Up there with invisibility, teleportation, and being able to cancel mid-season TV breaks, x-ray vision is one of the most sought after superpowers — and that seems to be what a couple of researchers from MIT have managed to do. It isn’t quite x-ray vision — it uses microwaves instead — but MIT’s radar array, made by Gregory Charvat and John Peabody, can see through 8-inch concrete walls. Basically, it works just like a normal radar system: 44 antennae send out S-band microwaves (2-4GHz, about 10cm peak to peak). Most of these microwaves — 99.4% — bounce off the solid concrete wall. The 0.6% that make it through bounce off any objects on the other side, and then come back through the wall, losing another 99.4% of the waves. By the time the microwaves return to the array, the signal is just 0.0025% of its original strength. The reflected waves are then amplified, subtracted from the concrete wall's echo using an analog crystal filter, and then converted into moving blobs by a computer. The entire rig is about 8 feet wide, and it is designed to be mounted on a military truck for urban warfare — but it could revolutionize emergency response, too, with the ability to see through rubble and collapsed buildings for survivors." Link to Original Source
Computers are unreliable, but humans are even more unreliable.
Any system which depends on human reliability is unreliable.