thermodynamics (5)

Quantum Time...

 

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"Weird Time Tunnel." Image Source Below.

 

Topics: Quantum Computer, Quantum Mechanics, Thermodynamics

It's easy to take time's arrow for granted - but the gears of physics actually work just as smoothly in reverse. Maybe that time machine is possible after all?

An experiment from 2019 shows just how much wiggle room we can expect when it comes to distinguishing the past from the future, at least on a quantum scale. It might not allow us to relive the 1960s, but it could help us better understand why not.

Researchers from Russia and the US teamed up to find a way to break, or at least bend, one of physics' most fundamental laws of energy.

The second law of thermodynamics is less a hard rule and more of a guiding principle for the Universe. It says hot things get colder over time as energy transforms and spreads out from areas where it's most intense.

It's a principle that explains why your coffee won't stay hot in a cold room, why it's easier to scramble an egg than unscramble it, and why nobody will ever let you patent a perpetual motion machine.

Virtually every other rule in physics can be flipped and still make sense. For example, you could zoom in on a game of pool, and a single collision between any two balls won't look weird if you happened to see it in reverse.

On the other hand, if you watched balls roll out of pockets and reform the starting pyramid, it would be a sobering experience. That's the second law at work for you.

Electrons aren't like tiny billiard balls, they're more akin to information that occupies a space. Their details are defined by something called the Schrödinger equation, which represents the possibilities of an electron's characteristics as a wave of chance.

Physicists Have Reversed Time on The Smallest Scale Using a Quantum Computer
Mike McCrae, Science Alert

 

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Kondo Effect...

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Daniel Mazzone led the project to explore the mechanism that causes samarium sulphide to expand dramatically when cooled. Credit: Brookhaven National Laboratory

 

Topics: Materials Science, Quantum Mechanics, Research, Thermodynamics

Most metals expand when heated and contract when cooled. A few metals, however, do the opposite, exhibiting what’s known as negative thermal expansion (NTE). A team of researchers led by Ignace Jarrige and Daniel Mazzone of Brookhaven National Laboratory in the US has now found that in one such metal, yttrium-doped samarium sulphide (SmS), NTE is linked to a quantum many-body phenomenon called the Kondo effect. The work could make it possible to develop alloys in which positive and negative expansion cancel each other out, producing a composite material with a net-zero thermal expansion – a highly desirable trait for applications in aerospace and other areas of hi-tech manufacturing.

Even within the family of NTE materials, yttrium-doped SmS is an outlier, gradually expanding by up to 3% when cooled over a few hundred degrees. To better understand the mechanisms behind this “giant” NTE behavior, Mazzone and Jarrige employed X-ray diffraction and spectroscopy to investigate the material’s electronic properties.

The researchers carried out the first experiments at the Pair Distribution Function (PDF) beamline at Brookhaven’s National Synchrotron Light Source (II) (NSLS-II). They placed their SmS sample inside a liquid-helium cooled cryostat in the beam of the synchrotron X-rays and measured how the X-rays scattered off the electron clouds around the atomic ions. By tracking how these X-rays scatter, they identified the locations of the atoms in the crystal structure and the spacings between them.

“Our results show that, as the temperature drops, the atoms of this material move farther apart, causing the entire material to expand by up to 3% in volume,” says Milinda Abeykoon, the lead scientist on the PDF beamline.

Kondo effect induces giant negative thermal expansion, Belle Dumé, Physics World

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Angry Summers...

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Credit: David Gray Getty Images

 

Topics: Climate Change, Existentialism, Global Warming, Thermodynamics


In the U.S., it is post the winter solstice: tilted 23.5 degrees away from the sun, our days are shorter, nights are longer and we usually experience precipitation in the forms of rain and snow.

The southern hemisphere is tilted the same degrees TOWARDS the sun, thus it's their summer. A summer typically marked by tourism, lazy beaches, mixed drinks and one would assume selfies of once-in-a-lifetime experiences. This is what was the usual and typical.

No hellscape could be penned more bleak than what we're seeing now. A billion living creatures have died, and likely are headlong barreling to the endangered species list. The elderly, sick and disabled are cannon fodder. The prime minister, firmly in the pockets of big coal, is as much a climate change lunatic as our current lobotomized "leader."

Oh yes, endangered species are not important now, are they (even if its us)? The "Environmental Protection Agency" is oxymoron. Climate change is a Chinese hoax, and the Australians just need better "forest management" by sweeping as advised to California and (not-at-all) practiced by residents of Finland. If soon-to-be past is prologue, we can only expect a repeat performance in the northern hemisphere once we get past May, especially in states like Texas, where water rationing by zip code is more or less expected, and a spark on a curb scratched by the pipe of a pickup truck in high heat and drought can cause infernos.

Avarice and abject ignorance will kill us all.

Summer in Australia use to be something we yearned for: long, lazy days spent by the beach or pool, backyard barbecues, and games of cricket with family and friends. But recent summers have become a time of fear: Schools and workplaces are closed because of catastrophic fire danger, while we shelter in air-conditioned spaces to avoid dangerous heat waves and hazardous levels of smoke in the air. Campgrounds have been closed for the summer, and entire towns have been urged to evacuate ahead of “Code Red” fire weather. Welcome to our new climate.

Of course, unusually hot summers have happened in the past; so have bad bushfire seasons. But the link between the current extremes and anthropogenic climate change is scientifically indisputable.

The fires raging across the southern half of the Australian continent this year have so far burned through more than 5 million hectares. To put that in context, the catastrophic 2018 fire season in California saw nearly 740,000 hectares burned. The Australian fire season began this year in late August (before the end of our winter). Fires have so far claimed nine lives, including two firefighters, and destroyed around 1,000 homes. It is too early to tell what the toll on our wildlife has been, but early estimates suggest that around 500 million animals have died so far, including 30 percent of the koala population in their main habitat. And this is all before we have even reached January and February, when the fire season typically peaks in Australia.
 

 

Australia’s Angry Summer: This Is What Climate Change Looks Like
Nerilie Abram, Scientific American

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Internet Carnot...

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Credit: ALFRED T. PALMER/VICTOR TANGERMANN

 

Topics: Climate Change, Existentialism, Internet, Thermodynamics


The Carnot cycle is the only thermodynamic cycle that is reversible, because compression and expansion of the gas are isentropic (no heat flow), while heating and cooling are isothermal (T does not change, only P and V), meaning that no energy is lost into increasing the system's entropy. Quora

The world is modeled using "ideal" circumstances: the Ideal Gas Law also comes to mind. You obviously start with this, initially.

Then, you have to model based on the reality, the biology, chemistry and physics of the actual case at hand.

Basing a civilization on a non-renewable resource of dead dinosaurs is a recipe to become museum artifacts ourselves.

As far as environmental damage is concerned, our increasingly-online lives incur a massive toll.

If everything continues on its current course, then the internet is expected to generate about 20 percent of the world’s carbon emissions by 2030, according to The New Republic. That would make its environmental impact worse than any individual country on Earth, except for the U.S., China, or India.

In other words, our internet use is linked to a vicious cycle of environmental devastation, making it increasingly clear that something has to give.

 

In the Face of Climate Change, the Internet is Unsustainable, Dan Robitzski, Futurism

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Twisted Fridge...

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Fridge-freezer: twistocaloric cooling could be coming to a kitchen near you. (Courtesy: iStock/Allevinatis)

 

Topics: Applied Physics, Green Tech, Research, Thermodynamics


A new refrigeration technology based on the twisting and untwisting of fibers has been demonstrated by a team led by Zunfeng Liu at Nankai University in China and Ray Baughman at the University of Texas at Dallas in the US. As the demand for refrigeration expands worldwide, their work could lead to the development of new cooling systems that do not employ gases that are harmful to the environment.

The cooling system relies on the fact that some materials undergo significant changes in entropy when deformed. As far back as 1805 – when the concepts of thermodynamics were first being developed – it was known that ordinary rubber heats up when stretched and cools down when relaxed. In principle, such mechanocaloric materials could be used in place of the gases that change entropy when compressed and expanded in commercial refrigeration systems. Replacing gas-based systems is an important environmental goal because gaseous refrigerants tend to degrade the ozone layer and are powerful greenhouse gases.

In their experiments, Liu and Baughman’s team studied the cooling effects of twist and stretch changes in twisted, coiled and supercoiled fibers of natural rubber, nickel-titanium and polyethylene fishing line. In each material, they observed a surface cooling as high as 16.4 °C, 20.8 °C, and 5.1 °C respectively, which they achieved through techniques including simultaneous releases of twisting and stretching, and unraveling bundles of multiple wires.

 

Refrigerator works by twisting and untwisting fibers, Materials, Physics World

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