Posted on 07/28/2023 10:44:15 AM PDT by Red Badger
Researchers have developed a device that can disrupt the relationship between the absorption and emission efficiencies of an object, essentially violating Kirchhoff’s law of thermal radiation. This law, in place for over 150 years, states that an object’s ability to absorb and emit energy is equal at each wavelength and angle of incidence. This breakthrough could significantly impact sustainable energy harvesting systems and certain types of camouflage technology. (Artist’s concept.)
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Scientists have developed a device that can break the principles of Kirchhoff’s law of thermal radiation, disrupting the traditional relationship between absorption and emission efficiencies in an object. This novel approach could enhance the efficiency of energy-harvesting systems and affect camouflage technologies.
If you take an object and set it out in the sun, it will begin to warm up. This is because it is absorbing energy from the sun’s rays and converting that energy to heat. If you leave that object outside it will continue getting warmer, but only to a point. A sunbather lying on a beach won’t catch fire, after all.
As objects (or people) absorb energy (light from the sun), they also emit energy (infrared radiation, or heat). This is something you may have experienced while walking past a block wall on a summer afternoon and feeling heat emanating from it.
Understanding Kirchhoff’s Law The connection between an object’s ability to absorb and emit energy in the form of electromagnetic radiation—its absorptive and emissive efficiencies—has long been explained by something known as Kirchhoff’s law of thermal radiation. The law, a concept devised by Gustav Kirchhoff in 1860, which states absorptive and emissive efficiencies are equal at each wavelength and angle of incidence. (A more in-depth explanation of Kirchhoff’s law can be found here.)
Breaking Kirchhoff’s Law A new device developed in the lab of Harry Atwater, the Howard Hughes Professor of Applied Physics and Materials Science, breaks that normally tight relationship between the absorbed and emitted efficiencies of an object. The invention may also have important implications for sustainable energy harvesting systems and the development of certain kinds of camouflage.
“Kirchhoff’s law has been upheld for more than 150 years, and while theoretical proposals for its violation have been advanced before, this is the first experimental proof that this law can be broken,” says Atwater.
Looking Into the Future of Energy Absorption Electrical engineering graduate student Komron Shayegan, lead author of the new research, further explains:
“The equality dictated by Kirchhoff’s law has been a guiding principle in the design of devices that absorb and emit energy in the form of radiation, because by designing around and measuring the absorptive properties of a material, we get the emissive properties for free. However, there has been a recent shift when designing emitters/absorbers, namely that we are trying to move beyond having a simple one-to-one equality between the emissivity and absorptivity of a body. “One motivation behind decoupling the two is in energy-harvesting systems. For example, if an energy-harvesting object, like a photovoltaic (solar panel), is re-emitting some of its absorbed energy back toward the energy source (the Sun) as heat, that energy is lost to human purposes. In theory, if the photovoltaic— or other energy-harvesting object —were to re-emit absorbed radiation away from the source and toward yet another energy-harvesting object, one could reach higher energy conversion efficiencies.
“Our study shows that it is possible to break the equality of Kirchhoff’s law of thermal radiation with a device placed in a moderate magnetic field. The device itself combines a material that has a strong magnetic-field response with a patterned structure that enhances absorption and emission in infrared wavelengths. What is particularly exciting is that we can observe the effect by simply heating the device above room-temperature and directly comparing the emissive efficiency to the absorptive efficiency.”
The paper describing the work, “Direct Observation of Kirchhoff Thermal Radiation Law Violation,” appears in the July 24 issue of the journal Nature Photonics.
Reference: “Direct observation of the violation of Kirchhoff’s law of thermal radiation” by Komron J. Shayegan, Souvik Biswas, Bo Zhao, Shanhui Fan and Harry A. Atwater, 24 July 2023, Nature Photonics. DOI: 10.1038/s41566-023-01261-6
Co-authors are Souvik Biswas, formerly of Caltech and now at Stanford University; Bo Zhao of the University of Houston; Shanhui Fan of Stanford University; and Harry Atwater, who is also the Otis Booth Leadership Chair of the Division of Engineering and Applied Science and director of the Liquid Sunlight Alliance.
Funding for the research was provided by the Defense Advanced Research Projects Agency.
You can efficiently break the law harvesting electricity beneath cross-country electrical wires, using a metal roof on a shed…
Outlaw ping!..................
Using this one weird trick?
Until you get caught...................
If true, is a breakthrough with vast implications.
I just plug an extension cord into my neighbor’s outdoor plug.
I think John Galt should sequester this machine.
This doesn’t break the laws of thermodynamics............
If anything breaks a physical law, the law was wrong.
Does the electric utility own the land where those high energy lines and towers lie or do they merely have right-a-ways? How much energy can be scavenged from them by landowners or transient campers? enough to do anything with? I do recall seeing people waving fluorescent light bulb rods while standing under them and seeing them light up somewhat. Related, I presume?
Dumb statement by the writer: Whether we've discovered something or not, Physics either exists or it doesn't. The isn't any physical property or behavior that suddenly appears and starts obeying new rules.
I’m no physicist, duh, but it sounds like thermal radiation is just waste radiation from heat when it is in excess of what can be used and these scientists have managed to figure out how to keep it from being wasted, resulting in a reduction or prevention of thermal radiation. It could be useful for maybe making cars more efficient, if it can be adapted.
It doesn’t sound like they broke any laws to me.
Kind of..................
Which is why the WOKE cultists will never allow it to be used.
Must have "equality".
Especially if the magnetic field can be produced with permanent magnets, rather than electromagnets that require energy.
You mean scientists have reversed engineered some alien tech.
Star Trek really was true science fiction, the old ones. Sure, Kirk shagged his way through the universe and it was entertaining, BUT:
Communicators, i.e. cell and or phones that can communicate from earth to space like Iridium.
Touchscreens, tablets, Flat Panel TVs, Virtual Reality, tractor beams (optical tweezers using lasers really exist today on a microscopic level), AI, speech recognition, lasers, holograms...
You need to realize, something as simple as a self opening door using IR barriers, motion detectors or other means while already invented were not common in 1966 when the show first aired.
Today the old shows seem corny, but it really was true science fiction with Roddenberry doing his homework on what future tech might bring us.
Sadly, what he didn’t foresee is how friggin androgenous we would become in the future, you surely won’t see a LT Ohura showing her legs today anywhere, and half the men out there don’t deserve to have testicles.
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