thermodynamics (11)

Fourth Signature...

10265218097?profile=RESIZE_710x

How can you tell if a material is a superconductor? Four classic signatures are illustrated here. Left to right: 1) It conducts electricity with no resistance when chilled below a certain temperature. 2) It expels magnetic fields, so a magnet placed on top of it will levitate. 3) Its heat capacity – the amount of heat needed to raise its temperature by a given amount – shows a distinctive anomaly as the material transitions to a superconducting state. 4) And at that same transition point, its electrons pair up and condense into a sort of electron soup that allows current to flow freely. Now experiments at SLAC and Stanford have captured this fourth signature in cuprates, which become superconducting at relatively high temperatures, and show that it occurs in two distinct steps and at very different temperatures. Knowing how that happens in fine detail suggests a new and very practical direction for research into these enigmatic materials. (Courtesy: Greg Stewart, SLAC National Accelerator Laboratory)

Topics: Condensed Matter Physics, Superconductor, Thermodynamics

Researchers in the US report that they have observed the so-called “fourth signature” of superconducting phase transitions in materials known as cuprates. The result, obtained via photoemission spectroscopy of a cuprate called Bi2212, could shed fresh light on how these materials, which conduct electricity without resistance at temperatures of 77 K or higher, transition into the superconducting state.

The superconducting transition occurs when a material loses all resistance to an electrical current below a certain critical temperature Tc. At this temperature, bulk materials exhibit four characteristic “signatures” – electrical, magnetic, thermodynamic, and spectroscopic – indicating that transition has occurred. The electrical signature is the development of zero resistance. The magnetic signature is the onset of the Meissner effect – that is, the material expels magnetic fields. And the thermodynamic signature is that the material’s heat capacity (the amount of heat required to increase its temperature by a given value) displays a distinctive anomaly.

Elusive superconducting-transition signature seen for the first time, Isabelle Dumé, Physics World

Read more…

Thermo Limits

10249327499?profile=RESIZE_584x

A radical reimagining of information processing could greatly reduce the energy use—as well as greenhouse gas emissions and waste heat—from computers. Credit: vchal/Getty Images

Topics: Climate Change, Computer Science, Electrical Engineering, Global Warming, Semiconductor Technology, Thermodynamics

In case you had not noticed, computers are hot—literally. A laptop can pump out thigh-baking heat, while data centers consume an estimated 200 terawatt-hours each year—comparable to the energy consumption of some medium-sized countries. The carbon footprint of information and communication technologies as a whole is close to that of fuel used in the aviation industry. And as computer circuitry gets ever smaller and more densely packed, it becomes more prone to melting from the energy it dissipates as heat.

Now physicist James Crutchfield of the University of California, Davis, and his graduate student Kyle Ray have proposed a new way to carry out computation that would dissipate only a small fraction of the heat produced by conventional circuits. In fact, their approach, described in a recent preprint paper, could bring heat dissipation below even the theoretical minimum that the laws of physics impose on today’s computers. That could greatly reduce the energy needed to both perform computations and keep circuitry cool. And it could all be done, the researchers say, using microelectronic devices that already exist.

In 1961 physicist Rolf Landauer of IBM’s Thomas J. Watson Research Center in Yorktown Heights, N.Y., showed that conventional computing incurs an unavoidable cost in energy dissipation—basically, in the generation of heat and entropy. That is because a conventional computer has to sometimes erase bits of information in its memory circuits in order to make space for more. Each time a single bit (with the value 1 or 0) is reset, a certain minimum amount of energy is dissipated—which Ray and Crutchfield have christened “the Landauer.” Its value depends on ambient temperature: in your living room, one Landauer would be around 10–21 joule. (For comparison, a lit candle emits on the order of 10 joules of energy per second.)

‘Momentum Computing’ Pushes Technology’s Thermodynamic Limits, Phillip Ball, Scientific American

Read more…

Time...

9817128673?profile=RESIZE_710x

GIF source: article link below

Topics: Applied Physics, Education, Research, Thermodynamics

Also note the Hyper Physics link on the Second Law of Thermodynamics, particularly "Time's Arrow."

"The two most powerful warriors are patience and time," Leo Tolstoy, War, and Peace

The short answer

We can measure time intervals — the duration between two events — most accurately with atomic clocks. These clocks produce electromagnetic radiation, such as microwaves, with a precise frequency that causes atoms in the clock to jump from one energy level to another. Cesium atoms make such quantum jumps by absorbing microwaves with a frequency of 9,192,631,770 cycles per second, which then defines the international scientific unit for time, the second.

The answer to how we measure time may seem obvious. We do so with clocks. However, when we say we’re measuring time, we are speaking loosely. Time has no physical properties to measure. What we are really measuring is time intervals, the duration separating two events.

Throughout history, people have recorded the passage of time in many ways, such as using sunrise and sunset and the phases of the moon. Clocks evolved from sundials and water wheels to more accurate pendulums and quartz crystals. Nowadays when we need to know the current time, we look at our wristwatch or the digital clock on our computer or phone. 

The digital clocks on our computers and phones get their time from atomic clocks, including the ones developed and operated by the National Institute of Standards and Technology (NIST).

How Do We Measure Time? NIST

Read more…

Quantum Exorcism...

9786514062?profile=RESIZE_584x

Figure 2. Maxwell’s demon is a hypothetical being that can observe individual molecules in a gas-filled box with a partition in the middle separating chambers A and B. If the demon sees a fast-moving gas molecule, it opens a trapdoor in the partition to let fast-moving molecules into chamber B while leaving slow-moving ones behind. Repeating that action would allow the buildup of a temperature difference between the two sides of the partition. A heat engine could use that temperature difference to perform work, which would contradict the second law of thermodynamics.

Topics: Chemistry, History, Materials Science, Quantum Mechanics, Thermodynamics

Thermodynamics is a strange theory. Although it is fundamental to our understanding of the world, it differs dramatically from other physical theories. For that reason, it has been termed the “village witch” of physics.1 Some of the many oddities of thermodynamics are the bizarre philosophical implications of classical statistical mechanics. Well before relativity theory and quantum mechanics brought the paradoxes of modern physics into the public eye, Ludwig Boltzmann, James Clerk Maxwell, and other pioneers of statistical mechanics wrestled with several thought experiments, or demons, that threatened to undermine thermodynamics.

Despite valiant efforts, Maxwell and Boltzmann were unable to completely vanquish the demons besetting the village witch of physics—largely because they were limited to the classical perspective. Today, experimental and theoretical developments in quantum foundations have granted present-day researchers and philosophers greater insights into thermodynamics and statistical mechanics. They allow us to perform a “quantum exorcism” on the demons haunting thermodynamics and banish them once and for all.

Loschmidt’s demon and time reversibility

Boltzmann, a founder of statistical mechanics and thermodynamics, was fascinated by one of the latter field’s seeming paradoxes: How does the irreversible behavior demonstrated by a system reaching thermodynamic equilibrium, such as a cup of coffee cooling down or a gas spreading out, arise from the underlying time-reversible classical mechanics?2 That equilibrating behavior only happens in one direction of time: If you watch a video of a wine glass smashing, you know immediately whether the video was in rewind or not. In contrast, the underlying classical or quantum mechanics are time-reversible: If you were to see a video of lots of billiard balls colliding, you wouldn’t necessarily know whether the video was in rewind or not. Throughout his career, Boltzmann pursued a range of strategies to explain irreversible equilibrating behavior from the underlying reversible dynamics. Boltzmann’s friend Josef Loschmidt famously objected to those attempts. He argued that the underlying classical mechanics allow for the possibility that the momenta are reversed, which would lead to the gas retracing its steps and “anti-equilibrating” to the earlier, lower-entropy state. Boltzmann challenged Loschmidt to try to reverse the momenta, but Loschmidt was unable to do so. Nevertheless, we can envision a demon that could. After all, it is just a matter of practical impossibility—not physical impossibility—that we can’t reach into a box of gas and reverse each molecule’s trajectory.

Technological developments since Loschmidt’s death in 1895 have expanded the horizons of what is practically possible (see figure 1). Although it seemed impossible during his lifetime, Loschmidt’s vision of reversing the momenta was realized by Erwin Hahn in 1950 in the spin-echo experiment, in which atomic spins that have dephased and become disordered are taken back to their earlier state by an RF pulse. If it is practically possible to reverse the momenta, what does that imply about equilibration? Is Loschmidt’s demon triumphant?

The demons haunting thermodynamics, Katie Robertson, Physics Today

Read more…

Breaking Physics...

 

Topics: Quantum Computer, Quantum Mechanics, Thermodynamics

In what could prove to be a momentous accomplishment for fundamental physics and quantum physics, scientists say they’ve finally figured out how to manufacture a scientific oddity called a time crystal.

Time crystals harness a quirk of physics in which they remain ever-changing yet dynamically stable. In other words, they don’t give off energy as they change conformation, making them an apparent violation of the natural law that all things gradually turn towards entropy and disorder.

Now, it seems like it’s possible for these things to exist, after all, Quanta Magazine reports. At least, that’s according to what a massive team of researchers from Stanford, Princeton, and elsewhere working with Google’s quantum computing labs claimed in preprint research shared online last week. Aside from being an incredible scientific discovery in abstract — time crystals represent a new, bizarre phase of matter — the discovery could have profound implications for the finicky world of quantum computing.

“The consequence is amazing: You evade the second law of thermodynamics,” study coauthor and Max Planck Institute for the Physics of Complex Systems director Roderich Moessner told Quanta.

Google Claims To Create Time Crystals Inside Quantum Computer, Dan Robitzski, Futurism

Read more…

Power Density...

9222023659?profile=RESIZE_710x

Optimal size: wind farm efficiency drops as installations become bigger. (Courtesy: iStock/ssuaphoto)

Topics: Alternate Energy, Climate Change, Existentialism, Global Warming, Green Tech, Thermodynamics

Optimizing the placement of turbines within a wind farm can significantly increase energy extraction – but only until the installation reaches a certain size, researchers in the US conclude. This is just one finding of a computational study on wind turbines’ effects on the airflow around them, and consequently the ability of nearby turbines – and even nearby wind farms – to extract energy from that airflow.

Wind power could supply more than a third of global energy by 2050, so the researchers hope their analysis will assist in better designs of wind farms.

It is well known that the efficiencies of turbines in a wind farm can be significantly lower than that of a single turbine on its own. While small wind farms can achieve a power density of over 10 W/m2, this can drop to a little as 1 W/m2 in very large installations The first law of thermodynamics dictates that turbines must reduce the energy of the wind that has passed through them. However, turbines also inject turbulence into the flow, which can make it more difficult for downstream turbines to extract energy.

“People were already aware of these issues,” says Enrico Antonini of the Carnegie Institution for Science in California, “but no one had ever defined what controls these numbers.”

Optimal size for wind farms is revealed by computational study, Tim Wogan, Physics World

Read more…

Quantum Time...

 

weird_time_tunnel_cover_1024.jpg
"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

 

Read more…

Kondo Effect...

227888.jpg
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

Read more…

Angry Summers...

6E29B90E-E7D9-46AF-9DC660AAA45BF510_source.jpg
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

Read more…

Internet Carnot...

Smokestacks.JPG
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

Read more…

Twisted Fridge...

Twisted-fridge.jpg
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

Read more…