Cosmic rays are high-energy particles from space, mostly protons and atomic nuclei, that strike Earth’s atmosphere and create showers of secondary particles. They are invisible, constant, and difficult to eliminate completely, which makes them a common source of background noise in sensitive measurements.
In cyber security and computing, cosmic rays matter because they can cause soft errors: temporary bit flips in memory, sensors, or storage controllers. A random particle strike can corrupt a calculation, crash a process, or subtly alter data without any malicious actor involved. Defenses include error-correcting memory, parity checks, redundant systems, checksum validation, and physical shielding. In ultra-sensitive experiments, like low-background detectors, the same particles can obscure the signal being measured, so teams place equipment underground or add shielding to reduce interference.