The conversation between human and AI assistant.
Can a photon be at rest or does it have to travel at the speed of light?
Interesting. Can photons ever lose energy and change their wavelength?
Yes, photons can lose energy and change their wavelength through a process known as scattering, where they interact with matter and transfer some of their energy to it. This can happen, for example, when sunlight hits the Earth's atmosphere and causes the sky to appear blue.