the.com/wavelength
the ruler the universe uses to measure light, sound, and whether two people click.
means The distance between two corresponding points of a wave — crest to crest or trough to trough — that determines a wave's color, pitch, or character.
from A transparent compound of "wave" and "length," assembled by 19th-century physicists as the wave theory of light and sound took hold and demanded a name for that crest-to-crest span. "Wave" traces back to Old English wafian, to move to and fro, while "length" comes from Old English lengþu, kin to "long." The figurative sense — being "on the same wavelength" as someone — is a 20th-century gift from radio, where two sets must tune to the same wavelength to hear each other at all.
- size range
- From kilometers-long radio to atom-tiny gamma rays
- color code
- Your eyes read wavelength as red through violet
- shorter punches harder
- Tiny wavelengths carry the biggest energy
- slang origin
- Radio operators tuned to the same broadcast frequency
- redshift
- Stretched wavelengths prove the universe keeps expanding
lyman alpha line — ultraviolet emission at 121.6 nm from hydrogen, key for studying early universe galaxies
balmer series h-alpha — red hydrogen line at 656 nm, used to measure stellar rotation and solar prominences