109

In a surprising finding, light can make water evaporate without heat (news.mit.edu)

submitted 11 months ago by m3t00@lemmy.world to c/science@lemmy.world

38 comments fedilink hide all child comments

all 40 comments

sorted by: hot top controversial new old

[-] Oszilloraptor@feddit.de 20 points 11 months ago

Uh, I'm surprised.

I learned this in school more than a decade ago.

Did my teacher accidentally lied the truth?

[-] rdyoung@lemmy.world 21 points 11 months ago

Light is energy. This isn't surprising to me at all.

[-] Lmaydev@programming.dev 30 points 11 months ago

The energy transfer to evaporate water is the heat. This is specifically without heat.

They proved more water was evaporated than the heat applied to the water.

The theory being the light knocks away water particles at the surface of the water without heating them.

[-] bouh@lemmy.world 11 points 11 months ago

So, in fact, water will evaporate without heat because of the lack of equilibrium between air and water, until the air is wet enough for the process to stop.

Discovering that light vaporise water is not the same as discovering that water vaporise itself without heat. It is an interesting discovery nonetheless.

[-] Lmaydev@programming.dev 7 points 11 months ago

Up to 3 times more water evaporated than heat energy the light could supply.

It's pretty massive if true.

[+] rdyoung@lemmy.world -12 points 11 months ago

That's literally not possible. It may be heat that we don't have sensitive enough equipment to detect but light is energy and it hitting the water will release heat.

[-] Lmaydev@programming.dev 8 points 11 months ago

I mean that's literally what this study has shown. So it is indeed completely possible.

[+] rdyoung@lemmy.world -22 points 11 months ago* (last edited 11 months ago)

I don't think you have the grasp on things that you think you do. I'm not in the mood nor do I have the time to have a beginners class on this so I suggest you do some reading on your own and learn how to analyze things and come to your own conclusions. Way way too many studies are straight up faked at worst, at best they are tweaked and results that say something different are thrown out or ignored.

By this logic, when we heat up food or drinks in the microwave we are not using heat at all. We are in fact generating heat as the water molecules are excited by the energy in the radio waves being transmitted towards whatever is in the microwave. For those who may not know, radio waves are just light we can't see because our eyes don't have whats needed to see them.

You know what. Ignore everything I said above and keep on keeping on. Stay ignorant and full of yourself. See how far that gets you in life.

[-] Jtotheb@lemmy.world 12 points 11 months ago

I hope you lack the time because you’re setting up your own study. This one was set up due to previous observations of rates of evaporation double or greater than those understood to be mathematically possible. Hell of an equipment error. It also observes a difference in the rate of evaporation under different colors of light, with the highest rate of evaporation occurring under green light, which you would probably also deem impossible, since color has nothing to do with it and green isn’t even the most energetic wavelength. An MIT professor, a postdoc, and four others hang their hat on these results, and the reality of this phenomenon. rdyoung disagrees with them in a comments section on an obscure forum. Which source might be more credible?

[+] rdyoung@lemmy.world -18 points 11 months ago

You also definitely don't understand what I or the study is saying. Not surprised here at all.

Again, as I said. Maybe we don't have the tech to read the miniscule amount of heat in a photon of light or the heat generated as the light excites the water molecules, that doesn't mean that heat wasn't a part of it.

Yet another one who has no idea or grasp of the concepts at play here.

Just like reddit, I thought a sub such as this would have a smarter community but once again you lot proved me wrong and showed me that no matter how dumb I think people can be, they can always surprise you with the idiocy.

I'll leave you with a quote from Harvey Danger.

Been around the world and found That only stupid people are breeding.

[-] Lmaydev@programming.dev 12 points 11 months ago

Just like Reddit you're being an absolute asshole for no reason.

[-] Mobiuthuselah@lemm.ee 9 points 11 months ago

Lighten up. This is no way to have a productive discussion. If you aren't in the mood, then maybe you shouldn't be commenting right now. Take a breather. We all have bad days. Hope you feel better.

[-] Jtotheb@lemmy.world 8 points 11 months ago* (last edited 11 months ago)

You replied to a fairly accurate summary of the postulated explanation of an observed phenomena by saying it’s literally impossible. Either the study is faking its* data, or the study has real data but you don’t like the way definitions are playing out here. You’re arguing for both, because it’s really important that this study is wrong, because you don’t like it. But it can’t be both. Let’s assume PNAS didn’t publish a completely fraudulent study about a made-up phenomenon.

The thermal heat that is being transferred is what causes evaporation. That’s the historical understanding. Yes? Energy in, energy out. 1:1 ratio, everything is conserved. But it’s evaporating twice as fast as that measured heat transfer explains. 1=2? That’s not right. Saying “it’s just more heat that you can’t measure” doesn’t make any sense, because you’re claiming that 1.0004 = 2. It’s a new process. Yeah, something happened on a molecular level and there was probably heat transfer. But on a completely different scale than the known process of evaporation through actual ‘macro’ heat transfer. So it’s not the fucking same.

Again, the green thing. If evaporation is caused only by previously understood processes of heat transfer—more energy is more heat transfer is more evaporation—then why does a less energetic green light produce more evaporation than a more energetic blue or violent light?

“The researchers tried to duplicate the observed evaporation rate with the same setup but using electricity to heat the material, and no light. Even though the thermal input was the same as in the other test, the amount of water that evaporated never exceeded the thermal limit. However, it did so when the simulated sunlight was on, confirming that light was the cause of the extra evaporation.”

Sorry to steal so much of your time, but if you’re not fucking what’s so damn important

[-] elbarto777@lemmy.world 1 points 11 months ago

Don't feed the troll.

[-] surewhynotlem@lemmy.world 4 points 11 months ago

First, being rude makes you look like you don't know what you're talking about. Condescension in technology and science is very 'last century'.

Second, you're right. This article is a bad translation at best. If the light interacted with the water in any way that produced motion and caused evaporation, that motion IS heat.

They probably mean to say that they can evaporate water directly with light without having to use a heating element or something non-water to absorb the light. That's my best guess at translating a poorly written article at least.

[-] Jtotheb@lemmy.world 6 points 11 months ago* (last edited 11 months ago)

From the abstract: “We interpret these observations by introducing the hypothesis that photons in the visible spectrum can cleave water clusters off surfaces due to large electrical field gradients and quadrupole force on molecular clusters.”

The commenter’s interpretation of the summary was pretty close to the language Chen used.

To be clear, this article is written by an English native speaker who is summarizing a study written in English primarily by a man who’s been at U.S. universities for three decades. Unless you meant it was a bad summary, which I don’t think it was, but that’s opinion.

[-] Lmaydev@programming.dev 1 points 11 months ago

No they literally state more water was evaporated than heat energy from the light could do by up to 3 times.

[-] surewhynotlem@lemmy.world 0 points 11 months ago

That's assuming some definition of heat that requires light absorbtion. This is still heat, because all motion of atoms is heat.

[-] elbarto777@lemmy.world 0 points 11 months ago

Haha, what a nice trolling attempt!

[+] WoahWoah@lemmy.world 0 points 11 months ago* (last edited 11 months ago)

[deleted]

[-] rdyoung@lemmy.world 1 points 11 months ago* (last edited 11 months ago)

What exactly are you talking about? What in any of my comments here lead you to that assumption? Or were you so horned up to make that comment that you responded to the wrong person?

As for my marriage. Happier than you could ever hope to be and having more sex in a week than you probably have in a decade all while working a reasonable number of hours and taking time off whenever I feel like it (I am self employed). Also buying a house and 3+ acres. Take a ton of vacations, see ever concert we can fit in to our schedule and even some we shouldn't. For example, just saw Theory Of a Deadman, Saint Asonia and Skillet in Salem VA. Have Creed next summer, Hagar, Vai, etc next spring iirc among others.

If you had any working braincells you would cross reference my username here on other platforms. That would give you an idea of who I am, what I am and what the fuck is really going on here.

I don't actually want your answer here so I will be proactively blocking you.

[-] WoahWoah@lemmy.world 1 points 11 months ago* (last edited 11 months ago)

You had been really angry in your comments recently, but I'm sorry for offending you.

Since it seems to bother you so much, I'll delete the comment for you. I hope that helps.

Also, I wasn't one of the people arguing with you about the topic of the thread.

[-] PeachMan@lemmy.world 9 points 11 months ago

Yeah that's the part that confuses me....how does one transfer energy to something without generating any heat?

[-] JanoRis@lemmy.world 20 points 11 months ago

They explain that in the article. Light barely gets absorbed in water, which is why you can see several meters deep in water. Only the absorbed part can turn into heat.

They measured an effect that partly evaporates water more efficiently than the heat influx can. The theory mentioned in the article is, that light directly knocks out water molecules at the water/air surface boundary. The measured effect was the most effective with light of a green wavelength

[-] TheOneCurly@lemmy.theonecurly.page 4 points 11 months ago

Heat doesn't really exist at an individual particle level, it only describes the average kinetic energy of a large number of particles. "Normal" evaporation occurs because all the water molecules are jiggling around fast enough that sometimes some get knocked off at the top and fly away. The theory from this paper says that light can strike a single water molecule just right that it breaks off without help from the others.

Saying this is "without heat" means that the light isn't simply increasing the average kinetic energy at the top of the water and speeding up the rate of "normal" evaporation. They think it's specifically acting on a single molecule at a time.

[-] Jtotheb@lemmy.world 12 points 11 months ago

Okay, this study has absolutely fascinated me. Tried to find the full study but failed, but Gang Chen (MIT professor, primary author) has a 40 minute symposium about it. Piped bot incoming, hopefully: https://m.youtube.com/watch?v=B1PbNTYU0GQ

[-] steeznson@lemmy.world 6 points 11 months ago

Potentially the bot will struggle with a mobile link but depends on the regexes it is using. I'd be surprised if it didn't find it though!

[-] m3t00@lemmy.world 6 points 11 months ago

I like pounding YouTube on firefox with full ad-blocks engaged. hehe funny how nobody noticed. light is a range of frequencies so I'd expect best results at some harmonic frequencies.

[-] m3t00@lemmy.world 8 points 11 months ago

green is best

[-] m3t00@lemmy.world 2 points 11 months ago

seems like harmonic frequencies should be interesting. I'm forgetting some facts but how does microwave line up with green light. with respect to harmonics. thought MIT didn't use clickbait headlines. https://duckduckgo.com/?q=green+light+frequencies+chart+microwave+harmonic+series

ps. be nice

[-] Fedizen@lemmy.world 5 points 11 months ago

is this analogous to the photoelectric effect?

[-] m3t00@lemmy.world 3 points 11 months ago

photoelectric effect?

looks similar. pe frees electrons while this experiment frees h2o molecules. they didn't really speculate on the exact mechanism. only something to do with the gel medium

this post was submitted on 29 Nov 2023

109 points (95.8% liked)

science

14595 readers

81 users here now

just science related topics. please contribute

note: clickbait sources/headlines aren't liked generally. I've posted crap sources and later deleted or edit to improve after complaints. whoops, sry

Rule 1) Be kind.

lemmy.world rules: https://mastodon.world/about

I don't screen everything, lrn2scroll

founded 1 year ago

MODERATORS

m3t00@lemmy.world

Joleee@lemmy.world

laverabe@lemmy.world

DeadPand@midwest.social