I usually see myself as being pretty solid on my general science knowledge, but this one continues to stump me.
Light is photons, little particles that move through space… but then it’s also a wave, like the visible light portion of the electromagnetic spectrum? How can it be both? How would photons red shift over great distances? Do we just not know what light is, really?
In: 9
The best explanation I can think of is: light is a particle, but particles act like waves.
Particles (not just photons, but also bigger particles such as electrons, protons, whole atoms, and bigger things still) act like waves in the following senses:
* they can have interference patterns – such as in the double-slit experiment, which still shows an interference pattern even when you send the particles in one by one.
* they can have a well-defined wavelength, that depends on their mass and speed
* they don’t have a perfectly well-defined location
* their motion can be described by a kind of “wave equation”.
You might be thinking “hey, that baseball I threw didn’t act like a wave!” the thing is, the baseball is such a massive object that its wavelength is too tiny to detect anything wavelike about the way it moves. Waves with tiny wavelengths act like particles, after all: they travel in straight lines, reflect off things, get blocked by things, and so on.
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