The evaporation of liquid water into steam or mist is one of the most extensively researched physical processes on Earth.
In a surprising turn of events, scientists at the Massachusetts Institute of Technology (MIT) believe they have discovered a completely new source of evaporation, with potential effects on liquid water that surpass even those of heat.
What could this source be? Light itself.
The researchers anticipate skepticism and opposition, which is why they are already collaborating with other experts to verify their findings and hypotheses.
If their claims prove accurate, this discovery will fundamentally alter the way climate scientists comprehend the water cycle.
Since ancient Greece times, philosophers and mathematicians have pondered the peculiar way tiny liquid droplets seem to float through the air as the Sun rises.
Modern experiments and calculations using the scientific method have revealed heat as a major player in this process.
However, high temperatures may not be the sole force propelling water molecules.
According to new experiments, light alone could have the power to dislodge water’s molecular structure.
This discovery solves a problem that mathematicians have grappled with for the past few years: the evaporation rate of water doesn’t always align with expectations. The amount of heat absorbed by water doesn’t account for all the liquid lost during evaporation experiments.
In a 2022 study, for example, scientists achieved an evaporation rate 278 percent higher than the thermal limit of liquid water.
The MIT researchers initially doubted these findings, but after conducting their own experiments, they realized another force must be at work. Further investigations revealed that a flow of photons generating light without heat can cause liquid water to evaporate in the laboratory.
This finding is fascinating because while liquid water is known for absorbing heat energy, it doesn’t typically absorb much light. Hence, when there is no silt and sufficient sunlight, the ocean floor remains visible from several meters above.
Although the evaporative effect has only been demonstrated in the lab using a hydrogel material saturated with water, the researchers believe a similar process may occur on the ocean’s surface, in clouds, or in fog.
Their experiments involved illuminating the hydrogel with various colored lights and measuring the amount of water lost by mass. The lights were shielded to prevent heat transmission, yet the researchers observed puffs of condensation emanating from the material.
For comparison purposes, the team then subjected the hydrogel to heat using electricity instead of light.
When subjected to heat alone, the amount of water evaporated never exceeded the thermal limit. However, when both heat and light were applied, the thermal limit was exceeded.
The MIT researchers have dubbed this phenomenon the ‘photomolecular effect’.
They propose that if light without heat can indeed trigger evaporation, desalination processes could become three or four times more efficient than they are currently.
“This could potentially revolutionize affordable desalination,” says mechanical engineering Gang Chen from MIT.
As with any significant scientific paradigm shift, this discovery will undoubtedly face intense scrutiny. Other teams are already contemplating their own attempts to reproduce the results.
Meanwhile, MIT has received numerous grants to investigate how the ‘photomolecular effect’ can enhance desalination systems and climate change modeling.
We may never see evaporation in the same light again.
Their study was published in the journal PNAS.
