Getting jobs done with photons

Just a reminder—photons are the best description we have of what helps us see.

Radiations can both warm and illuminate: which depends on the frequency of the photon and on what kind of creature is doing the looking, or on the absorbing material.

Arrange it so that photons arrive and are absorbed, and there will be illuminating or warming. The greater the number of photons every second, or the higher the frequency, the greater the illuminating or warming.


Warming something is supplying power. More photons every second provides more power. But what's emitted and what's detected may not be the same—it depends on what's between source and detector.

The number of photons absorbed each second set the warming.


The brightness of a beam of a particular colour is set just by the photon count: put an absorber in the way to reduce the brightness. The power is the brightness of the beam.

But the colour of the beam can alter as well, and that also sets the warming.

Finally, just like seeing, the photons have to be absorbed to warm, and any material only absorb some frequencies. So how much the object is warmed also depends on what it is made of, and even whether it is polished, like a mirror, or not. It's complicated.