water evaporates thanks to light, even without heat

2023-11-08 05:00:15

Evaporation, the ubiquitous phenomenon that sees water change from a liquid to a gas, is a process that we all learned regarding from a young age. We know that heat is the source of energy (In the common sense, energy refers to anything that allows us to carry out work, make energy, etc.) which allows water to evaporate, in particular thanks to to the sun (The Sun (Sol in Latin, Helios or Ήλιος in Greek) is the star…). However, a recent scientific discovery challenges this widely accepted idea. Researchers at the Massachusetts Institute of Technology (MIT) have revealed that light is all electromagnetic waves visible to the eye. ..), alone, can cause the evaporation of water, more effectively than heat (In common language, the words heat and temperature often have an equivalent meaning:…). This discovery, which pushes the limits of our understanding of natural phenomena, has major implications for various fields, ranging from climatology to desalination. water in particular. Evaporation is the process by which water molecules on the surface of a liquid absorb enough energy to transform into gas, thus creating vapor () water. Until now, it was widely accepted that this energy came mainly from heat, particularly solar heat. However, recent observations have left scientists perplexed. They noticed that in some experiments, water evaporated at a much higher rate than might be explained by quantity. .) of heat to which she was exposed. Sometimes the evaporation rate even exceeded twice the theoretical thermal limit.

To understand this phenomenon, MIT researchers conducted a series of experiments. They used a hydrogel material (a sponge-like material) to contain the water and exposed this hydrogel to different wavelengths of light. The results were astounding. Water was evaporating at rates much higher than the thermal limit should have allowed. Additionally, the evaporation rate appeared to vary across wavelengths, with peak efficiency at green light. This dependence on the color of light reinforced the idea that evaporation was not only linked to the heat.

The researchers called this phenomenon the “photomolecular effect”. They hypothesized that photons of light might “cleave” groups of water molecules near the surface of the liquid, causing evaporation. Although this discovery was made in the laboratory, scientists believe that it might also occur in nature, for example on the sea surface or in clouds.

Evaporation of water from a hydrogel

The implications of this discovery are vast. First, it might improve our understanding of natural processes, such as the formation of clouds and fog. Indeed, by integrating this photomolecular effect into climate models, it would be possible to obtain more precise forecasts. Furthermore, this discovery might revolutionize the water desalination industry. Currently, desalination typically involves converting sunlight into heat to cause water to evaporate. However, thanks to the photomolecular effect, it is possible to considerably increase the efficiency of this process. Researchers estimate that desalination yield might be tripled, or even quadrupled, using this method. This might potentially lead to more affordable and sustainable desalination solutions. The discovery that light affects the evaporation of water without heat is a major scientific breakthrough. It challenges our traditional knowledge of evaporation and opens new perspectives in areas ranging from climatology to water desalination. The MIT team plans to further their research on the subject in order to consider concrete applications.
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