Advanced radiative cooling through meta-materials

[YNM]

15 minutes ago, p1t1o said:

Or more likely, its a discovery of some far more banal effect, and they've dressed it up in language to make it seem like they can break previously unassailable physics. 

On this point, I'd like to ask @K^2 :

Can visible wavelength transmit heat ? Or is it just IR ?

[Brotoro]

So... they are just making panels that are thin film interference filters with high transmission in the 8 to 13 micrometer band, and very low transmission (high reflectivity) in at the optical wavelengths where the Sun has its peak intensity?

[Xd the great]

15 hours ago, YNM said:

On this point, I'd like to ask @K^2 :

Can visible wavelength transmit heat ? Or is it just IR ?

Yes. When the photons we can see hit stuff, the stuff absorbs and reflects light of certain wavelength. So maybe IR. And the IR does its job.

Plus visible light is just hyper IR.

[TheDestroyer111]

The title of this video is a violation of the second law of thermodynamics. So to build this device, we would have to find an alternate universe.

[p1t1o]

12 minutes ago, TheDestroyer111 said:

The title of this video is a violation of the second law of thermodynamics. So to build this device, we would have to find an alternate universe.

This is one of the things which irks me, inventing made-up nonsensical headlines to get the heaving masses to read about some niche discovery they will never care about. What it does is erode the public confidence in real science since they are force-fed the manufactured impression that science never delivers.

And oh look! The reputation of science is at an all-time low today! Antivaxxers. Homeotherapy. The moon landing is a hoax. The Earth is flat. And all of this in the clear-as-day presence of obvious, visible, in-your-face physical evidence to the contrary. That is how powerful the anti-science drive is today.

Everytime some scientist (or possibly more accurately, journalist) promises a world-changing, physics re-modelling, mind shattering breakthrough and it turns out to be a transistor that runs 0.1K cooler, another thousand flat-earthers are born.

STOP IT

SERIOUSLY

As a scientist I will resist this from of dissemination automatically, hence my earlier rather negative review.

[magnemoe]

19 hours ago, p1t1o said:

This is one of the things which irks me, inventing made-up nonsensical headlines to get the heaving masses to read about some niche discovery they will never care about. What it does is erode the public confidence in real science since they are force-fed the manufactured impression that science never delivers.

And oh look! The reputation of science is at an all-time low today! Antivaxxers. Homeotherapy. The moon landing is a hoax. The Earth is flat. And all of this in the clear-as-day presence of obvious, visible, in-your-face physical evidence to the contrary. That is how powerful the anti-science drive is today.

Everytime some scientist (or possibly more accurately, journalist) promises a world-changing, physics re-modelling, mind shattering breakthrough and it turns out to be a transistor that runs 0.1K cooler, another thousand flat-earthers are born.

STOP IT

SERIOUSLY

As a scientist I will resist this from of dissemination automatically, hence my earlier rather negative review.

Most of this is because internet make it more visible and this also give more supporters, Antivaxxers and Homeotherapy is old, Flat earth is probably trolls with an few exceptions. 
But yes we also get lot more bad click-bait science news as we get more news, still remember the regular tabloid nourishment news on all the food who was bad for you making eat carrots or salat while it still healthy an joke. 

Honestly i don't really get how this work, I think its very reflective in all wavelengths outside an narrow gap there its very little radiation from other sources. 
But it will still get heated by the air unless insulated as in behind isolated glass 

[Streetwind]

Since my choice to link an easily digestible youtube video ruffled enough feathers to prompt two thread pages of mockery and dangerously high blood pressure, I apologize for jeopardizing everyone's health. Here is a proper article from the journal Nature from one and a half years ago that I found after thirty seconds on Google: https://www.nature.com/articles/ncomms13729

The specific experiment it describes isn't exactly the most real-world applicable, since it was intentionally designed to maximize the result in order to check if theoretical models of the maximum possible effect are sound. But the article does give a good overview of the physical principles involved.

 

Edited July 4, 2018 by Streetwind

[p1t1o]

1 hour ago, Streetwind said:

Since my choice to link an easily digestible youtube video ruffled enough feathers to prompt two thread pages of mockery and dangerously high blood pressure, I apologize for jeopardizing everyone's health. Here is a proper article from the journal Nature from one and a half years ago that I found after thirty seconds on Google: https://www.nature.com/articles/ncomms13729

The specific experiment it describes isn't exactly the most real-world applicable, since it was intentionally designed to maximize the result in order to check if theoretical models of the maximum possible effect are sound. But the article does give a good overview of the physical principles involved.

 

I apologise, Im not mad at you - all you did was tell us something you found interesting online - all of my ire is directed at the concept of poor science reporting.

Im definitely a bit jaded, after having seen approx 10,000 of these "shocking" and "mind blowing" (ugh) discoveries.

***

Thanks very much for posting the link to the paper, as you can see, it by itself would hardly get many clicks on tweettube or socialface because its not promising amazing things and doesnt contain any soundbites you can use to sound cool.

"However, the temperature reduction experimentally demonstrated, thus far, has been relatively modest." Doesnt make quite as good a headline does it.

The really irritating thing is that its actually quite an interesting paper, but dressing it up in fancy language does nothing for its credibility, especially when it fails to instantly deliver to the public.

It appears whoever annotated the youtube video is mostly to blame, mainly for silly language and not linking to the real paper (its 2018, this is the internet, and this is science, this is a big red flag). If I googled every youtube video that had a fantastic premise, I'd have to quit my job. But another minor apology is probably due as I am always saying things like "Just spend 5 seconds on google GAWD". Chalk it up to the aforementioned jading, but perhaps I should soften myself a bit.

***

From a skim of the paper the device seems to work by using a "selective emitter" to radiate specific wavelengths through an atmospheric "transparency window" at 8-13um.

They do actually achieve some quite striking results, though it should be noted that sunshields were used in all cases. This is cooling against ambient air temperature, not in direct sunlight.

It should also be noted that the paper never identifies the selective emitter, and metamaterials are only mentioned in one reference used to illustrate the long history of radiative cooling.

Does the youtuber have inside knowledge of the experimental setup? Or did they scan the article looking for buzzwords?

I dont know the answer to that but the mere fact that the question exists is what makes me mad.

***

Oh, and it should also be noted that this would have no use in space, as it is specifically designed to minimise the impact of an insulating atmosphere. 

 

Edited July 4, 2018 by p1t1o

[Streetwind]

9 minutes ago, p1t1o said:

Does the youtuber have inside knowledge of the experimental setup? Or did they scan the article looking for buzzwords?

...Erm? o_O

I'm honestly not sure if we're talking about the same youtube video, mind. But the one I linked in the first post is a recording from the April 2018 TED conference, on the official TED channel. The on-stage presenter is Aaswath Raman, from Standford University, one of the lead scientist of the group that is doing this research. You'll see him credited in the Nature article.

 

Edited July 4, 2018 by Streetwind

[p1t1o]

47 minutes ago, Streetwind said:

...Erm? o_O

I'm honestly not sure if we're talking about the same youtube video, mind. But the one I linked in the first post is a recording from the April 2018 TED conference, on the official TED channel. The on-stage presenter is Aaswath Raman, from Standford University, one of the lead scientist of the group that is doing this research. You'll see him credited in the Nature article.

 

Ok so he has inside knowledge  thats my bad. If Im honest I didnt pay too much attention to the video (see: "jaded" above). And to be even more honest Im probably not going to pay much attention to the next on either, good science comes out when it comes out.

They sure were keeping the characteristics of the emitter close to their chests in the paper, it was conspicuous in its absence. 

**edit**

On closer inspection, I probably should have paid more attention to the video, and I probably would have been less...mouthy...but I stand by all the points about scientific journalism. There's a lesson - if you feel yourself getting angry, stop talking/writing. You can always go back later.

 

Edited July 4, 2018 by p1t1o