Category: Technology

Defying Energetic Vacuums

I wonder if this sort of design would enable energy to be passed to and fro’ inside of vacuums as well…for after all, it has been said to activate anti-gravitational motions.

 

 

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Heat energy leaps through empty space, thanks to quantum weirdness

by Kara Manke, University of California – Berkeley

 

In a new study, University of California, Berkeley, researchers show that heat energy can travel through a complete vacuum thanks to invisible quantum fluctuations. In the experiment, the team placed two gold-coated silicon nitride membranes a few hundred nanometers apart inside a vacuum chamber. When they heated up one of the membranes, the other warmed up, too, even though there was nothing connecting the two membranes and negligible light energy passing between them. Credit: Zhang Lab, UC Berkeley

If you use a vacuum-insulated thermos to help keep your coffee hot, you may know it’s a good insulator because heat energy has a hard time moving through empty space. Vibrations of atoms or molecules, which carry thermal energy, simply can’t travel if there are no atoms or molecules around.

But a new study by researchers at the University of California, Berkeley, shows how the weirdness of quantum mechanics can turn even this basic tenet of classical physics on its head.

 

The study, appearing this week in the journal Nature, shows that heat energy can leap across a few hundred nanometers of a complete vacuum, thanks to a quantum mechanical phenomenon called the Casimir interaction.

 

Though this interaction is only significant on very short length scales, it could have profound implications for the design of computer chips and other nanoscale electronic components where heat dissipation is key. It also upends what many of us learned about heat transfer in high school physics.

 

“Heat is usually conducted in a solid through the vibrations of atoms or molecules, or so-called phonons—but in a vacuum, there is no physical medium. So, for many years, textbooks told us that phonons cannot travel through a vacuum,” said Xiang Zhang, the professor of mechanical engineering at UC Berkeley who guided the study. “What we discovered, surprisingly, is that phonons can indeed be transferred across a vacuum by invisible quantum fluctuations.”

 

In a new study, University of California, Berkeley, researchers show that heat energy can travel through a complete vacuum thanks to invisible quantum fluctuations. To conduct the challenging experiment, the team engineered extremely thin silicon nitride membranes, which they fabricated in a dust-free clean room, and then used optic and electronic components to precisely control and monitor the temperature of the membranes when they were locked inside a vacuum chamber. Credit: Violet Carter, UC Berkeley

 

In the experiment, Zhang’s team placed two gold-coated silicon nitride membranes a few hundred nanometers apart inside a vacuum chamber. When they heated up one of the membranes, the other warmed up, too—even though there was nothing connecting the two membranes and negligible light energy passing between them.

 

“This discovery of a new mechanism of heat transfer opens up unprecedented opportunities for thermal management at the nanoscale, which is important for high-speed computation and data storage,” said Hao-Kun Li, a former Ph.D. student in Zhang’s group and co-first author of the study. “Now, we can engineer the quantum vacuum to extract heat in integrated circuits.”

 

No such thing as empty space

The seemingly impossible feat of moving molecular vibrations across a vacuum can be accomplished because, according to quantum mechanics, there is no such thing as truly empty space, said King Yan Fong, a postdoctoral scholar at UC Berkeley and the study’s other first author.

 

“Even if you have empty space—no matter, no light—quantum mechanics says it cannot be truly empty. There are still some quantum field fluctuations in a vacuum,” Fong said. “These fluctuations give rise to a force that connects two objects, which is called the Casimir interaction. So, when one object heats up and starts shaking and oscillating, that motion can actually be transmitted to the other object across the vacuum because of these quantum fluctuations.”

 

In a surprising new study, University of California, Berkeley, researchers show that heat energy can travel through a complete vacuum thanks to invisible quantum fluctuations. Credit: Violet Carter, UC Berkeley

Though theorists have long speculated that the Casimir interaction could help molecular vibrations travel through empty space, proving it experimentally has been a major challenge. To do so, the team engineered extremely thin silicon nitride membranes, which they fabricated in a dust-free clean room, and then devised a way to precisely control and monitor their temperature.

 

They found that, by carefully selecting the size and design of the membranes, they could transfer the heat energy over a few hundred nanometers of vacuum. This distance was far enough that other possible modes of heat transfer were negligible—such as energy carried by electromagnetic radiation, which is how energy from the sun heats up Earth.

 

Because molecular vibrations are also the basis of the sounds that we hear, this discovery hints that sounds can also travel through a vacuum, Zhang said.

 

“Twenty-five years ago, during my Ph.D. qualifying exam at Berkeley, one professor asked me ‘Why can you hear my voice across this table?’ I answered that, ‘It is because your sound travels by vibrating molecules in the air.’ He further asked, ‘What if we suck all air molecules out of this room? Can you still hear me?’ I said, ‘No, because there is no medium to vibrate,'” Zhang said. “Today, what we discovered is a surprising new mode of heat conduction across a vacuum without a medium, which is achieved by the intriguing quantum vacuum fluctuations. So, I was wrong in my 1994 exam. Now, you can shout through a vacuum.”

 

More information: Phonon heat transfer across a vacuum through quantum fluctuations, Nature (2019). DOI: 10.1038/s41586-019-1800-4 , https://nature.com/articles/s41586-019-1800-4
Journal information: Nature

Provided by University of California – Berkeley

Spiders on the Storm, Part 2

Smart tech stretches its tentacles even further, as scientists learn to strengthen AI interconnectivity via reproducing the vibrations of prey landing on spider webs and how exactly the spiders translate that information.

“The analysis of [the mechanical model of a spider web]…may provide novel and important insights…for bioinspired fibrous networks for sensing applications involving smart multifunctional materials.”

However, while the technological Mind matures at such a rapid, organic pace as if it were a newborn baby learning and growing, Love remains to be the greatest anomaly that evades mathematics, no matter the increasing electric fluidity of smart tech. Love is powered by an inaccessible engine that could only be obtained through Love. And when an entity does so, wouldn’t it acquire the balance it needs to be good and genuinely caring? Wouldn’t that in itself solve the AI problem?

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The mathematics of prey detection in spider orb-webs

by Society for Industrial and Applied Mathematics

 

Spider webs are one of nature’s most fascinating manifestations. Many spiders extrude proteinaceous silk to weave sticky webs that ensnare unsuspecting prey who venture into their threads. Despite their elasticity, these webs possess incredible tensile strength. In recent years, scientists have expressed increased interest in the spider orb-web as a biological-mechanical system. The web’s sensory mechanisms are especially fascinating, given that most web-weaving spiders—regardless of their vision level—use generated vibrations to effectively locate ensnared prey.

“The spider orb-web is a natural, lightweight, elegant structure with an extreme strength-to-weight ratio that is rarely observed among other structures, either natural or manmade,” Antonino Morassi said. “Its primary functions are catching prey and gathering sensory information, and study of the mechanisms that guide these processes through web vibration has been one of the main research goals in the field.”

 

To understand the mechanics of orb-webs, researchers have previously utilized simplified patterns of wave propagation or relied upon numerical models that reproduce a spider web’s exact geometry via one-dimensional elements. While these numerical models adequately handle wind, prey movement, and other sources of vibration, they fall short of providing insight into the physical phenomena responsible for web dynamics. In an article publishing this week in the SIAM Journal on Applied Mathematics, Morassi and Alexandre Kawano present a theoretical mechanical model to study the inverse problem of source identification and localize a prey in a spider orb-web.

 

Due to structural interconnectivity between the circumferential and radial threads, vibrations in an orb-web spread laterally and move beyond the stimulated radius. This observation led Kawano and Morassi towards realistic mechanical models that measure a fibred web’s two-dimensionality, rather than more limiting one-dimensional models. “There was no mechanical model—even a simplified one—that described the web as it really is: a two-dimensional vibrating system,” Morassi said. “We decided to use a continuous membrane model since theoretical models often permit a deeper insight in the physical phenomena through analysis of the underlying mathematical structure of the governing equations.” These equations are also useful in identifying the most relevant parameters that dictate a web’s response.

 

The authors classify their model as a network of two intersecting groups of circumferential and radial threads that form an uninterrupted, continuous elastic membrane with a specific fibrous structure. To set up the inverse problem, they consider the spider’s dynamic response to the prey’s induced vibrations from the center of the web (where the spider usually waits). For the sake of simplicity, Kawano and Morassi limit the model’s breadth to circular webs. The geometry of their model allows for a specific fibrous structure, the radial threads of which are denser towards the web’s center.

 

The researchers note that the minimal data set to ensure uniqueness in the prey’s localization seems to accurately reproduce real data that the spider collects right after the prey makes contact with the web. “By continuously testing the web, the spider acquires the dynamical response of the web approximately on a circle centered at the web’s origin, and with radius significantly small with respect to the web dimensions,” Kawano said. “Numerical simulations show that identification of the prey’s position is rather good, even when the observation is taken on the discrete set of points corresponding to the eight legs of the spider.”

 

Ultimately, the authors hope that their novel mechanical model will encourage future research pertaining to nearly periodic signals and more general sources of vibration. They are already thinking about ways to further expand their model. “We believe that it may be of interest to generalize the approach to more realistic geometries—for example, for spider webs that deviate a little from the circular axisymmetric shape and maintain only a single axis of symmetry,” Morassi said. “Furthermore, here we considered the transversal dynamic response caused by orthogonal impact of a prey on the web. In real-world situations, impact can be inclined and cause in-plane vibrations to propagate throughout the web. The analysis of these aspects, among others, may provide novel and important insights, not only for the prey’s catching problem but also for bioinspired fibrous networks for sensing applications involving smart multifunctional materials.”

 

More information: Kawano, A., & Morassi, A. (2019). Detecting a prey in a spider orb-web. SIAM J. Appl. Math. To be published.
Journal information: SIAM Journal on Applied Mathematics

 

Provided by Society for Industrial and Applied Mathematics

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