Imagine: some poor soul needs to repaint a section of their wall. Blissfully, uknowingly, they pull out their cell phone and open "Color Grab (color detection)", a 4.5-star app with over a million downloads. They point their phone camera at the wall, and the app tells them it is "Galliano". Oh, yes, Galliano, they think, this must be the color of my wall.
This person is so, so wrong. The app is so, so wrong. Everything about this is so, so wrong. Let's talk about why.
In the simplest terms, light is a bazillion little very fast-moving squiggles (I will not elaborate) called photons. Each photon has its own number that we call energy. For example, a white LED lightbulb emits about ten billion billion photons per second. Each of these photons has a different energy, which we can measure in units of electron-volts (eV). Most of the photons the lightbulb emits have energies between 2eV and 3eV. Because there are so many photons squiggling around, we typically don't worry about the energy of each individual photon. Instead, we consider the spectrum of photon energies. For example, this is the energy spectrum of sunlight at Earth's surface:
[photo]