Quantum electrodynamics (QED) is a quantum field theory that describes the interaction of light and matter. While QED primarily deals with the behavior of photons and electrons, it does not directly explain macroscopic phenomena like heat mirages. The phenomenon of a heat mirage is better understood through classical physics and the principles of optics.
A heat mirage is an optical illusion that occurs due to the bending of light as it passes through layers of air with different temperatures. When there is a significant temperature gradient in the air, such as above a hot surface on a sunny day, the light rays passing through the different air layers are refracted or bent at different angles. This bending of light causes the image of distant objects to appear distorted or displaced, creating the illusion of a mirage.
The key factors at play in the formation of a heat mirage are the temperature gradient and the variation in the refractive index of air with temperature. The refractive index of a medium determines how much light is bent when it enters the medium. In the case of a heat mirage, the air near the ground is hotter and has a lower density, leading to a lower refractive index compared to the cooler air above.
As light travels from the cooler air towards the hotter air near the ground, it encounters regions with gradually increasing temperatures. The change in refractive index at each layer causes the light to change direction continuously, creating a gradual bending or curving of the light rays. This bending results in the apparent displacement and distortion of the observed objects.
To summarize, the explanation of a heat mirage lies in classical optics and the principles of refraction rather than in quantum electrodynamics. While QED provides a fundamental understanding of the interaction between light and matter at the microscopic level, it does not directly address the macroscopic phenomenon of a heat mirage.