Imagine a world in which, by using only light, one can vaporize water without the need for heat—quite like something out of science fiction, isn’t it? All of this is now true, thanks to a groundbreaking finding by Massachusetts Institute of Technology scientists. Lately, with a new phenomenon labeled the “photomolecular effect,” the implication has become that only by using light, water can evaporate. It changes everything we know about its behavior and those multiple interactions with light.
For decades, researchers have been working on an 80-year-old mystery involving clouds’ absorption of more sunlight than our current theories can explain. This puzzle has important implications for our climate models and weather predictions. With this new discovery, we finally have a clue. This makes for very new, disturbing knowledge of light-water interactions,” said Xiulin Ruan, a professor of mechanical engineering at Purdue University. who was not part of the work. The discovery’s potential implications are huge. At one level, it seems to potentially blow away the solar desalination systems and render the production of fresh water far more efficient than today’s methods. It could be game-changing technology for water-scarce regions. “I think this has a lot of applications,” said Gang Chen, one of the MIT professors who conducted the research. “We’re exploring all these different directions. “Of course, it also affects the basic science, like the effects of clouds on climate being the most uncertain aspect of climate models.”
A research team based at Yale University, publishing in the journal Proceedings of the National Academy of Sciences, let slip how their 14 tight experiments proved the obvious: photons from visible light could force the evaporation of water clusters into the air. This does not happen in a laboratory; it occurs on massive scales in nature itself, and this changes everything we think we know about the process of evaporation. “The observations in the manuscript point to a new physical mechanism that changes fundamentally the way we think about the kinetics of evaporation,” says Shannon Yee, associate professor of mechanical engineering at Georgia Tech who wasn’t involved in the study.
What does that really mean for us? In practical terms, it points the way to new technologies for energy and producing clean water. This might mean better solar panels, or possibly systems that could condense fresh water out of seawater using just power generated by sunlight. Even more broadly, this discovery promises to be one that might help improve the accuracy of climate models a sustained thorn so far—which most of the time points to models of cloud behavior. Accurate models are extremely important, not only to predict the change in climate accurately, but also to mitigate it.
It might also prove useful in meteorological and oceanographic advances, among others. For instance, an insight into what light does at the interface with bodies of water might help in better weather prediction and climate modeling. “Who would have thought that we are still learning about something as quotidian as water evaporating?” added Yee.
The path to this discovery was less than a straight line. Skepticism had to be overcome, findings had to be vetted through countless trials by a research team. It’s like many of these groundbreaking findings that come to light: it’s likely a bit of time will pass before the results can be accepted into the general scientific community. For now, however, the first reaction is excitement with great expectation of where this will lead. “We are working in all these different directions,” says Jessica Grebeldinger, an author in the research.
Much more than a simple scientific revelation, to be aware of the photomolecular effect is to be present at an unsealed portal to the future of humanity. From the supply of fresh water in arid regions and improvements in our climate models to new routes towards energy solutions, the potential that this discovery holds is immeasurable. And who knows maybe the next time you look up at a cloud you’ll forget that it’s a floating mass of water droplets and see there a mystery whose unraveling has only finally started.
