Light and Chu theories
Chu’s statements are based on the optics, branch of physics whose main object of study is light. Light is a small fragment of the electromagnetic spectrum, characterized by its wavelengths (denoted magnitude λ) ranging between 400 and 700 nanometers.
The light is distinguished from other forms of electromagnetic waves because it is that which the human being can perceive through his eyes. Visual perception when the light that impacts a bjeto is reflected towards our eyes and affects the retinal sensory cells, which subsequently generate an electrical pulse that will be interpreted in the brain as an image. The perception of color, in particular, will depend on the wavelength of the light that affects the retina;Older waves are perceived as warm colors, such as red, orange and yellow, while lower waves are perceived as cold colors, within these are green, blue and violet. The main source of light on Earth is the sun, which emits white light. This is nothing more than multiple electromagnetic waves of different wavelengths moving simultaneously.
However, this light undergoes transformations when impacting a body. There are two transformations that are of special relevance to understand Chu’s claims, reflection and absorption. Reflection is the phenomenon that occurs when a wave affects a body and bounces from its surface, altering the wave displacement direction. Reflection, however, does not alter the wavelength, which means that, in the case of light, its color remains constant.
On the other hand, absorption is a specific phenomenon for electromagnetic waves. This consists of capturing electromagnetic radiation by a body. According to the principle of conservation of energy, the energy of the captured wave is subsequently transformed and irradiated as heat by the body that captured it. (West, S.F. ) 2 The black bodies, such as asphalt, absorb electromagnetic radiation of wavelengths between 400 and 700 nanometers, resulting in the fact that the totality of the energy of the incident light is transformed into heat.
White bodies, on the other hand, reflect electromagnetic radiation of wavelengths between 400 and 700 nanometers, resulting in a total reflection of light energy without producing heating in the body. Colorado bodies are a hybrid case: they reflect electromagnetic radiation of some wavelengths between 400 and 700 nanometers and absorb others;The color we perceive depends on what is reflected, while warming depends on what is absorbed. Knowing this, it is possible to understand the scientific bases of Chu’s statement.
The great ability to absorb black objects contributes to the increase in temperature worldwide and, additionally, promote the use of air conditioners and fans, increasing electricity consumption. If they were painted white, then sunlight would be reflected from their surfaces without increasing the temperature, a strategy that could be very useful to combat global warming and reduce electric consumption.