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Comment by Dr. Krishna Kumari Challa on April 24, 2024 at 10:03am

researchers have proposed a physical mechanism that can explain the angle and polarization dependence of the effect, showing that the photons of light can impart a net force on water molecules at the water surface that is sufficient to knock them loose from the body of water. But they cannot yet account for the color dependence, which they say will require further study.

They have named this the photomolecular effect, by analogy with the photoelectric effect that was discovered by Heinrich Hertz in 1887 and finally explained by Albert Einstein in 1905. That effect was one of the first demonstrations that light also has particle characteristics, which had major implications in physics and led to a wide variety of applications, including LEDs. Just as the photoelectric effect liberates electrons from atoms in a material in response to being hit by a photon of light, the photomolecular effect shows that photons can liberate entire molecules from a liquid surface, the researchers say.

The finding of evaporation caused by light instead of heat provides new disruptive knowledge of light-water interaction.
It could help us gain new understanding of how sunlight interacts with cloud, fog, oceans, and other natural water bodies to affect weather and climate. It has significant potential practical applications such as high-performance water desalination driven by solar energy.
The finding may solve an 80-year-old mystery in climate science. Measurements of how clouds absorb sunlight have often shown that they are absorbing more sunlight than conventional physics dictates possible. The additional evaporation caused by this effect could account for the longstanding discrepancy, which has been a subject of dispute since such measurements are difficult to make.

Those experiments are based on satellite data and flight data. They fly an airplane on top of and below the clouds, and there are also data based on the ocean temperature and radiation balance. And they all conclude that there is more absorption by clouds than theory could calculate. However, due to the complexity of clouds and the difficulties of making such measurements, researchers have been debating whether such discrepancies are real or not. And what was discovered now suggests that hey, there's another mechanism for cloud absorption, which was not accounted for, and this mechanism might explain the discrepancies.
Part 3

Comment by Dr. Krishna Kumari Challa on April 24, 2024 at 9:59am

The new work builds on research reported* last year, which described this new "photomolecular effect" but only under very specialized conditions: on the surface of specially prepared hydrogels soaked with water. In the new study, the researchers demonstrate that the hydrogel is not necessary for the process; it occurs at any water surface exposed to light, whether it's a flat surface like a body of water or a curved surface like a droplet of cloud vapour.

Because the effect was so unexpected, the team worked to prove its existence with as many different lines of evidence as possible. In this study, they report 14 different kinds of tests and measurements they carried out to establish that water was indeed evaporating—that is, molecules of water were being knocked loose from the water's surface and wafted into the air—due to the light alone, not by heat, which was long assumed to be the only mechanism involved.

One key indicator, which showed up consistently in four different kinds of experiments under different conditions, was that as the water began to evaporate from a test container under visible light, the air temperature measured above the water's surface cooled down and then leveled off, showing that thermal energy was not the driving force behind the effect.

Other key indicators that showed up included the way the evaporation effect varied depending on the angle of the light, the exact color of the light, and its polarization. None of these varying characteristics should happen because at these wavelengths, water hardly absorbs light at all—and yet the researchers observed them.

The effect is strongest when light hits the water surface at an angle of 45 degrees. It is also strongest with a certain type of polarization, called transverse magnetic polarization. And it peaks in green light—which, oddly, is the color for which water is most transparent and thus interacts the least.

* Yaodong Tu et al, Plausible photomolecular effect leading to water evaporation exceeding the thermal limit, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2312751120

Part 2

Comment by Dr. Krishna Kumari Challa on April 24, 2024 at 9:56am

How light can vaporize water without the need for heat

It's the most fundamental of processes—the evaporation of water from the surfaces of oceans and lakes, the burning off of fog in the morning sun, and the drying of briny ponds that leaves solid salt behind. Evaporation is all around us, and humans have been observing it and making use of it for as long as we have existed.

And yet, it turns out, we've been missing a major part of the picture all along.

In a series of painstakingly precise experiments, a team of researchers  has demonstrated that heat isn't alone in causing water to evaporate. Light, striking the water's surface where air and water meet, can break water molecules away and float them into the air, causing evaporation in the absence of any source of heat.

The astonishing new discovery could have a wide range of significant implications. It could help explain mysterious measurements over the years of how sunlight affects clouds, and therefore affect calculations of the effects of climate change on cloud cover and precipitation. It could also lead to new ways of designing industrial processes such as solar-powered desalination or drying of materials.

The findings, and the many different lines of evidence that demonstrate the reality of the phenomenon and the details of how it works, are described recently in the Proceedings of the National Academy of Sciences.

The authors say their study suggests that the effect should happen widely in nature—everywhere from clouds to fogs to the surfaces of oceans, soils, and plants—and that it could also lead to new practical applications, including in energy and clean water production.

Part 1

Comment by Dr. Krishna Kumari Challa on April 24, 2024 at 9:50am

Study suggests that living near green spaces reduces the risk of depression and anxiety

Over the past decades, a growing number of people have migrated to urban areas, while the size and population of rural areas have drastically declined. While parks and other green spaces are often viewed as beneficial for the well-being of those living in cities and urban regions, so far very few studies have explored the impact of these spaces on mental health.

Researchers recently carried out a study investigating the potential link between long-term exposure to green spaces in proximity of one's home and two of the most common mental health disorders: depression and anxiety. Their findings, published in Nature Mental Health, suggest that living close to parks and green areas can reduce the risk of becoming depressed and experiencing anxiety.

As part of their study, the researchers analyzed data gathered from 409,556 people and stored in the UK Biobank database. They specifically looked at the distance between participants and green areas, in conjunction with their self-reported well-being scores, as well as hospitalizations, hospital admissions, and deaths in their residential area.

The results of the analyses suggest that there is a link between prolonged proximity to residential green areas and the incidence of both depression and anxiety. Specifically, they suggest that living closer to parks and other green areas reduces the risk of experiencing both depression and anxiety.

Researchers draw the important conclusion that long-term exposure to residential greenness is associated with a decreased risk of incident depression and anxiety, and reduced air pollution in the greenest areas probably plays an important role in this trend. This  study thus implies that expanding urban green spaces could promote good mental health.

Jianing Wang et al, Long-term exposure to residential greenness and decreased risk of depression and anxiety, Nature Mental Health (2024). DOI: 10.1038/s44220-024-00227-z.

Comment by Dr. Krishna Kumari Challa on April 23, 2024 at 9:59am

Our current measurements of the visible universe, in other words, are insufficient to confirm which side the hidden sector fell on at the beginning—hot or cold.

Nath is quick to point out that, rather than a failing of the experiment, this is an example of the mathematical models outrunning our current experimental capabilities.

It's not that the difference between a hot or cold hidden sector has no bearing on the visible universe, but that we haven't performed experiments—yet—with high enough precision. Nath mentions the Webb Telescope as one example of the next generation of tools that will be able to make such precise observations.

The ultimate goal of all this modeling work is to make better predictions about the state of the universe, how it all functions and what we'll find when we look deeper and deeper into the night sky.

As our experiments gain more accuracy, the questions baked into Nath's models—was the hidden sector hot or cold?—will find their answers, and those clarified models will help predict the solutions to ever-deeper questions.
"What's the significance of this?" Nath asks. Human beings, he says, "want to find their place in the universe." And more than that, "they want to answer the question, why is there a universe?

"And we are exploring those issues. It is the ultimate quest of human beings."

Jinzheng Li et al, Big bang initial conditions and self-interacting hidden dark matter, Physical Review D (2023). DOI: 10.1103/PhysRevD.108.115008

Part 4

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Comment by Dr. Krishna Kumari Challa on April 23, 2024 at 9:59am

One major variable is the temperature of the hidden sector during the Big Bang.

The visible sector, we can be fairly certain, started out very hot at the moment of the Big Bang. As the universe cools, Nath says, "what we see is the remnant of that period of the universe."

But by studying the evolution of the two sectors, Nath and his team could model both conditions—a hidden sector that started out hot, and another hidden sector that started out cold.

What they observed was surprising: Despite significant differences between the models, with major implications on what the universe looked like in early times, both the hot and cold models were consistent with the visible sector we can observe today.
part 3

Comment by Dr. Krishna Kumari Challa on April 23, 2024 at 9:58am

But we can't explain everything, the authors of this study contends. There are anomalies that don't seem to fit the so-called "Standard Model" of the universe.

That the visible and hidden sectors are mutually isolated is a misconception, they say, based on an assumption "that the visible and the hidden sectors evolved independently of each other." The new work wants to turn that assumption on its head.

In a paper published in Physical Review D, "Big Bang Initial Conditions and Self-Interacting Hidden Dark Matter, they want to ask what they call "the more important question: How do we know that they evolved independently?"

To test this assumption, Nath and his team "introduced some feeble interactions" between the two sectors into their models of the Big Bang. These meager interactions wouldn't be enough to affect the outcome of, say, particle accelerator experiments, "but we wanted to see what the effects would be on the visible sector as a whole," Nath says, "from the time of the Big Bang to the current time."
Even with minimal interactions between the two sectors, Nath and his team discovered that dark matter's influence on the visible matter we're made of could have a major impact on observable phenomena.

The Hubble expansion—which says, in the simplest terms, that galaxies are moving away from one another, and thus that the universe is expanding—for instance, contains a "quite serious" differential between what the Standard Model predicts and what has been observed. Nath's models partially account for this difference.

Comment by Dr. Krishna Kumari Challa on April 23, 2024 at 9:52am

New models of Big Bang show that visible universe and invisible dark matter co-evolved

Physicists have long theorized that our universe may not be limited to what we can see. By observing gravitational forces on other galaxies, they've hypothesized the existence of "dark matter," which would be invisible to conventional forms of observation.

95% of the universe is dark, is invisible to the eye. 

However, we know that the dark universe is there by its gravitational pull on stars. Other than its gravity, dark matter has never seemed to have much effect on the visible universe.

Yet the relationship between these visible and invisible domains, especially as the universe first formed, has remained an open question.

Now, physicists say that there is mounting evidence that these two supposedly distinct realms actually co-evolved.

Through a series of computer models, physicists have discovered that the visible and the hidden sectors, as they call them, likely co-evolved in the moments after the Big Bang, with profound repercussions for how the universe developed thereafter.

They say there was a time when some physicists effectively wrote off this hidden sector, as they can explain most of what happens within the visible—that is, if our models can accurately portray what we can see happening around us, why bother trying to measure something that has no discernible effect?

The question is, what's the influence of the hidden sector on the visible sector?"  "But what do we care? We can explain everything."

Part 1

Comment by Dr. Krishna Kumari Challa on April 23, 2024 at 9:27am

The researchers now plan to use their electron videography technique to study other types of membrane proteins and other classes of molecules and nanomaterials.

 John W. Smith et al, Electron videography of a lipid–protein tango, Science Advances (2024). DOI: 10.1126/sciadv.adk0217

Part 4

Comment by Dr. Krishna Kumari Challa on April 23, 2024 at 9:26am

The researchers achieved videography by combining a novel water-based transmission electron microscopy method with detailed, atom-level computational modeling. The water-based technique involves encapsulating nanometer-scale droplets in graphene so they can withstand the vacuum in which the microscope operates. Comparing the resulting video data to molecular models, which show how things should move based on the laws of physics, helps the researchers not only interpret but also validate their experimental data.
Currently, this is really the only experimental way to film this kind of motion over time. Life is in liquid, and it's in motion. Scientists 're trying to get to the finest details of that connection in an experimental way.
For the new study—the first published demonstration of the electron videography technique—the researchers examined nanoscale discs of lipid membranes and how they interacted with proteins normally found on the surface of or embedded in cell membranes.
Part 3

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