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Banjo timbre from string stretching and frequency modulation

The geometry of a floating bridge on a drumhead soundboard produces string stretching that is first order in the amplitude of the bridge motion. This stretching modulates the string tension and consequently modulates string frequencies at acoustic frequencies. Early work in electronic sound synthesis identified such modulation as a source of bell-like and metallic timbre. And increasing string stretching by adjusting banjo string-tailpiece-head geometry is known to enhance characteristic banjo tone. Hence, this mechanism is likely a significant source of the ring, ping, clang, and plunk common to the family of instruments that share floating- bridge/drumhead construction. Incorporating this mechanism into a full, realistic model calculation remains an open challenge.

physics.pop-ph↗

Symmetrien, Teilchen und Felder

Symmetries are playing a very prominent role in natural sciences. In mathematics as the language of physics, symmetries are treated within the framework of group theory, which provides the tools to classify natural laws and physical objects like elementary particles. The present work discusses aspects of relativistic quantum field theory as the mathematical theory of particle physics which are relevant for the modern description of elementary particles and their associated fields hitherto considered as fundamental building blocks of the theory. Due to the abstract nature of quantum field theory, these aspects can only be touched by their exemplification within a review.

physics.pop-ph↗

El boson de Higgs

The last particle that completes the Standard Model of Elementary Particles, the most sophisticated theory of nature in human history, was discovered in 2012. Although the present formulation of the theory comes from the 1960s and 70s, it incorporates all discoveries that thousands of scientists made about elementary particles and their interactions (except for gravity) since the 1700s. Even if briefly, here we review the development of the major concepts included in the theory and explain the relevance of the new particle and the mechanism for which F. Englert and P. Higgs received the Nobel Prize in Physics 2013

physics.pop-ph↗

Nightfall: Can Kalgash Exist

We investigate the imaginary world of Kalgash, a planetary system based on the novel "Nightfall" (Asimov & Silverberg, 1991). The system consists of a planet, a moon and an astonishing six suns. The six stars cause the wider universe to be invisible to the inhabitants of the planet. The author explores the consequences of an eclipse and the resulting darkness which the Kalgash people experience for the first time. Our task is to verify if this system is feasible, from the duration of the eclipse, the "invisibility" of the universe to the complex orbital dynamics.

physics.pop-ph↗

Foucault precession manifested in a simple system

This article aims to answer the question, "What is the simplest system that embodies the essence of Foucault's pendulum?" We study a very elementary idealized system that exhibits a precession behavior analogous to the classic pendulum. The system consists of a particle without inertial mass, constrained to an inclined plane that rotates about a vertical axis. Insights gained from this analysis are used to understand the rate of precession in a straightforward way.

physics.pop-ph↗

How they (should have) built the pyramids

A novel method is proposed for moving large, pyramid construction size, stone blocks. The method is inspired by a well known introductory physics homework problem, and is implemented by tying 12 identical rods of appropriately chosen radius to the faces of the block. The rods form the corners and new faces that transform the square prism into a dodecagon which can then be moved more easily by rolling than by dragging. Experimental results are presented and compared to independent work by another group which utilized wooden attachments providing a cylindrical shape. It is found that a small scale stone block converted to dodecagons can be moved across level open ground with a dynamic coefficient of friction of the order 0.2. For full scale pyramid blocks, the wooden rods would need to be posts of order 30 cm in diameter, similar in size to those used as masts on ships in the Nile.

physics.pop-ph↗

Astrosociology: Interviews about an infinite universe

If the universe is infinite now it has always been infinite. This is the opinion of many astronomers today as can be concluded from the following series of interviews, but the opinions differ much more than I had expected. Many astronomers do not have a clear opinion on this matter. Others have a clear opinion, but very different from the majority. Detailed arguments by two experts on general relativity are also included. Observations show that the universe is flat, i.e. the curvature is zero within the small uncertainty of measurements. This implies an infinite universe, though most probably we will never know that for certain. For comparison with the recent interviews, opinions during the past 2300 years since Aristotle about the universe being finite or infinite have been collected from literature, and it appears that the scientists often had quite definite opinions. \c{opyright} Anita Publications. All rights reserved.

physics.hist-ph↗

Recorded Accounts of Meteoritic Events in the Oral Traditions of Indigenous Australians

Descriptions of natural events, such as fireballs and meteorite impacts, are found within Indigenous Australian oral traditions. Studies of oral traditions demonstrate that they extend beyond the realm of myth and legend; they contain structured knowledge about the natural world (science) as well as historic accounts of natural events and geo-hazards. These traditions could lead to the discovery of meteorites and impact sites previously unknown to Western science. In addition to benefiting the scientific study of meteoritics, this study can help social scientists better understand the nature and longevity of oral traditions and further support the growing body of evidence that oral traditions contain historical accounts of natural events. In a previous study led by the author in 2009, no meteorite-related oral traditions were identified that led to the discovery of meteorites and/or impact craters. This paper challenges those initial findings.

physics.hist-ph↗

Using Modern Technologies to Capture and Share Indigenous Astronomical Knowledge

Indigenous Knowledge is important for Indigenous communities across the globe and for the advancement of our general scientific knowledge. In particular, Indigenous astronomical knowledge integrates many aspects of Indigenous Knowledge, including seasonal calendars, navigation, food economics, law, ceremony, and social structure. We aim to develop innovative ways of capturing, managing, and disseminating Indigenous astronomical knowledge for Indigenous communities and the general public for the future. Capturing, managing, and disseminating this knowledge in the digital environment poses a number of challenges, which we aim to address using a collaborative project involving experts in the higher education, library, and industry sectors. Using Microsoft's WorldWide Telescope and Rich Interactive Narratives technologies, we propose to develop software, media design, and archival management solutions to allow Indigenous communities to share their astronomical knowledge with the world on their terms and in a culturally sensitive manner.

physics.pop-ph↗

Complex Network Approach to Number Theory

In this short paper, following the most recent advances in complex network theory, a new approach to number theory with potential applications to other fields is proposed. The model by Garcia-Perez, Serrano and Boguna, introduces an algorithm which allows to create a bipartite graph of integers (with primes and composites) statistically very close to the real one. Since the algorithm is defined a priori, we can have a description of the simulated prime number distribution in terms of a known differential equation, which in general can be treated more easily. The so determined properties of the simulated distribution can give useful hints about the behavior of the real prime number distribution. In principle it could be also possible to demonstrate open questions in number theory, proven the total equivalence of the simulated and real distributions.

physics.soc-ph↗

A Distributed Magnetometer Network

Various possiblities for a distributed magnetometer network are considered. We discuss strategies such as croudsourcing smartphone magnetometer data, the use of trees as magnetometers, and performing interferometry using magnetometer arrays to synthesize the magnetometers into a large-scale low-frequency radio telescope. Geophysical and other applications of such a network are discussed.

physics.geo-ph↗

Quantum teleportation of multiple properties of a single quantum particle

Quantum teleportation provides a "disembodied" way to transfer quantum states from one object to another at a distant location, assisted by priorly shared entangled states and a classical communication channel. In addition to its fundamental interest, teleportation has been recognized as an important element in long-distance quantum communication, distributed quantum networks and measurement-based quantum computation. There have been numerous demonstrations of teleportation in different physical systems such as photons, atoms, ions, electrons, and superconducting circuits. Yet, all the previous experiments were limited to teleportation of one degree of freedom (DoF) only. However, a single quantum particle can naturally possess various DoFs -- internal and external -- and with coherent coupling among them. A fundamental open challenge is to simultaneously teleport multiple DoFs, which is necessary to fully describe a quantum particle, thereby truly teleporting it intactly. Here, we demonstrate the first teleportation of the composite quantum states of a single photon encoded in both the spin and orbital angular momentum. We develop a method to project and discriminate hyper-entangled Bell states exploiting probabilistic quantum non-demolition measurement, which can be extended to more DoFs. We verify the teleportation for both spin-orbit product states and hybrid entangled state, and achieve a teleportation fidelity ranging from 0.57 to 0.68, above the classical limit. Our work moves a step toward teleportation of more complex quantum systems, and demonstrates an enhanced capability for scalable quantum technologies.

quant-ph↗

Brane World

This article attempts to discuss some key aspects of the Brane World scenario in a popular fashion, without using any formulas.

physics.pop-ph↗

A Stability Formula for Plastic-Tipped Bullets Part 1: Motivation and Development of New Formula

Part 1 of this paper describes a modification of the original Miller twist rule for computing gyroscopic bullet stability that is better suited to plastic-tipped bullets. The original Miller twist rule assumes a bullet of constant density, but it also works well for conventional copper (or gilding metal) jacketed lead bullets because the density of copper and lead are sufficiently close. However, the original Miller twist rule significantly underestimates the gyroscopic stability of plastic-tipped bullets, because the density of plastic is much lower than the density of copper and lead. Here, a new amended formula is developed for the gyroscopic stability of plastic-tipped bullets by substituting the length of just the metal portion for the total length in the $(1 + L^2)$ term of the original Miller twist rule. Part 2 describes experimental testing of this new formula on three plastic-tipped bullets. The new formula is relatively accurate for plastic-tipped bullets whose metal portion has nearly uniform density, but underestimates the gyroscopic stability of bullets whose core is significantly less dense than the jacket.

physics.pop-ph↗

The Quantum Wavefunction

When most people think of physics, they think of what they learned in high school physics: that the world is fundamentally predictable. Given the position and velocity of a particle in space, it should be possible to predict its position at any moment in the future, right? Though this was thought to be true for thousands of years, recent developments in the field of physics have shown that this isn't actually true. Instead of being fundamentally predictable, the universe is fundamentally unpredictable. However, this doesn't seem to make sense. What happened to the centuries of physics developed by Newton, Bernoulli, and Lagrange? Well, as it turns out, they weren't actually wrong. Their equations were actually an approximation of a formula called the wavefunction, which is the "Newton's Laws" equivalent for modern physics. In this paper, we'll take a look at this peculiar wavefunction and why our intuition about the world is completely wrong.

physics.pop-ph↗

A Stability Formula for Plastic-Tipped Bullets Part 2: Experimental Testing

Part 1 of this paper describes a modification of the original Miller twist rule for computing gyroscopic bullet stability that is better suited to plastic-tipped bullets. The original Miller twist rule assumes a bullet of constant density, but it also works well for conventional copper (or gilding metal) jacketed lead bullets because the density of copper and lead are sufficiently close. However, the original Miller twist rule significantly underestimates the gyroscopic stability of plastic-tipped bullets, because the density of plastic is much lower than the density of copper and lead. Here, a new amended formula is developed for the gyroscopic stability of plastic-tipped bullets by substituting the length of just the metal portion for the total length in the (1 + L2) term of the original Miller twist rule. Part 2 describes experimental testing of this new formula on three plastic-tipped bullets. The new formula is relatively accurate for plastic-tipped bullets whose metal portion has nearly uniform density, but underestimates the gyroscopic stability of bullets whose core is significantly less dense than the jacket.

physics.pop-ph↗