Physics - Popular Physics Publications (50)

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Physics - Popular Physics Publications

This article discusses the relationship between emergence and reductionism from the perspective of a condensed matter physicist. Reductionism and emergence play an intertwined role in the everyday life of the physicist, yet we rarely stop to contemplate their relationship: indeed, the two are often regarded as conflicting world-views of science. I argue that in practice, they compliment one-another, forming an awkward alliance in a fashion envisioned by the Renaissance scientist, Francis Bacon. Read More


A physical model is developed, which suggests a pathway to determining the optimal release conditions for a basketball free throw. Theoretical framework is supported by Monte Carlo simulations and a series of free throws performed and analysed at Southbank International School. The model defines a smile-shaped success region in angle-velocity space where a free throw will score. Read More


Quarks can be represented on the faces of the 3x3 Rubik's cube with the help of a symbolic representation of quarks and anti-quarks, that was delevoped originally for a deck of elementary particle cards, called Quark Matter Card Game. Cubing the cards leads to a model of the nearly perfect fluid of Quark Matter on Rubik's cube, or Qbe, which can be utilized to provide hands-on experience with the high entropy density, overall color neutrality and net baryon free, nearly perfect fluid nature of Quark Matter. Read More


Energy has always been the driving force in the technological and economic development of societies. The consumption of a significant amount of energy is required to provide basic living conditions of developed countries (heating, transportation, lighting, etc.). Read More


We introduce The Fabric of the Universe, an art and science collaboration focused on exploring the cosmic web of dark matter with unconventional techniques and materials. We discuss two of our projects in detail. First, we describe a pipeline for translating three-dimensional density structures from N-body simulations into solid surfaces suitable for 3D printing, and present prints of a cosmological volume and of the infall region around a massive cluster halo. Read More


Quantum technologies can be presented to the public with or without introducing a strange trait of quantum theory responsible for their non-classical efficiency. Traditionally the message was centered on the superposition principle, while entanglement and properties such as contextuality have been gaining ground recently. A less theoretical approach is focused on simple protocols that enable technological applications. Read More


Regulations governing METI are weak or non-existent. Post-detection SETI protocols are non-binding and too general. Vastly increased SETI capabilities, Chinese involvement in the field, and an intensified effort by METI-ists to initiate radio transmissions to the stars are among reasons cited for urgency in addressing the question of appropriate regulations. Read More


Recently it was shown that certain fluid-mechanical 'pilot-wave' systems can strikingly mimic a range of quantum properties, including double-slit interference, quantization of angular momentum etc. How far does this analogy go? Could such systems also violate a Bell inequality, despite the fact they involve only local (sub-luminal) interactions ? Here the premises of the Bell inequality are re-investigated for particles accompanied by a pilot-wave, or more generally by a 'background' field. We find that two of these premises, namely outcome independence and measurement independence, are not generally valid when a resonant background is present. Read More


Additive manufacturing of polymer bonded magnets is a recently developed technique, for single-unit production, and for structures that have been impossible to manufacture previously. Also new possibilities to create a specific stray field around the magnet are triggered. The current work presents a method to 3D print polymer bonded magnets with a variable magnetic compound density distribution. Read More


The LIGO-VIRGO collaboration has detected directly on Earth the gravitational wave signals generated by the collision and the merger of two massive black holes at astronomical distance. This major discovery opens up the way to Gravitational Astronomy, which should revolutionize our comprehension of the structure of the Universe at large scales, with notably the mechanisms of formation of black holes and their role in the evolution of the Universe, the likely emergence of a multi-messenger astronomy joint with electromagnetic radiation, and a better appraisal of the status of general relativity with respect to other fundamental interactions. The theoretical and numerical works on the two-body problem in general relativity play a very important role when deciphering and interpreting the gravitational wave signals. Read More


We discuss an apparent information paradox that arises in a materialist's description of the Universe if we assume that the Universe is 100% quantum. We discuss possible ways out of the paradox, including that Laws of Nature are not purely deterministic, or that gravity is classical. Our observation of the paradox stems from an interdisciplinary thought process whereby the Universe can be viewed as a "quantum computer". Read More


The momentum conservation law is applied to analyse the dynamics of pulsejet engine in vertical motion in a uniform gravitational field in the absence of friction. The model predicts existence of a terminal speed given frequency of the short pulses. The conditions that the engine does not return to the starting position are identified. Read More


The distribution of scientific citations for publications selected with different rules (author, topic, institution, country, journal, etc.) collapse on a single curve if one plots the citations relative to their mean value. We find that the distribution of shares for the Facebook posts re-scale in the same manner to the very same curve with scientific citations. Read More


The very humble origins of the Cyberspace, and all the related developments that smoothly conspired and converged towards this concept, making its emergence possible, as the personal computer, TEX and LATEX, the Fax, the internet, the cellphone, and the World Wide Web, are discussed, always from a personal perspective. A separate, comprehensive explanation of the reasons for the appearance and subsequent evolution of each of these different phenomena, with explicit assessments and a future prospective of the main subject, is presented. Read More


In a recent paper in Scientific Reports, Burridge \& Linden misinterpret the Mpemba effect as a statement about the rate of cooling of liquid water, when it is in fact a statement about the rate of freezing of water. Debunking an obviously absurd claim about cooling, they miss the significant effect, its only quantitative experimental study and a theoretical argument that explains the effect and predicts that it occurs only for "hard" water (water with significant dissolved Mg and Ca bicarbonates). This prediction remains to be tested. Read More


This work relates to the famous experiments, performed in 1975 and 1979 by Werner et al., measuring neutron interference and neutron Sagnac effects in the earth's gravitational field. Employing the method of Stodolsky in its weak field approximation, explicit expressions are derived for the two phase shifts, which turn out to be in agreement with the experiments and with the previously obtained expressions derived from semi-classical arguments: these expressions are simply modified by relativistic correction factors. Read More


Over the past several years, the authors have served as teachers, qualified scientists, mentors, and/or parents on dozens of science projects. These projects ranged from elementary school projects that can be completed in a weekend to high school and college freshmen projects that take a semester or year to complete and yield published scholarly papers and/or compete at the highest national and international levels. This article describes what we have observed to be important to success. Read More


A recurring topic in interstellar exploration and the search for extraterrestrial intelligence (SETI) is the role of artificial intelligence. More precisely, these are programs or devices that are capable of performing cognitive tasks that have been previously associated with humans such as image recognition, reasoning, decision-making etc. Such systems are likely to play an important role in future deep space missions, notably interstellar exploration, where the spacecraft needs to act autonomously. Read More


The 2016 Physics Nobel Prize honors a variety of discoveries related to topological phases and phase transitions. Here we sketch two exciting facets: the groundbreaking works by John Kosterlitz and David Thouless on phase transitions of infinite order, and by Duncan Haldane on the energy gaps in quantum spin chains. These insights came as surprises in the 1970s and 1980s, respectively, and they have both initiated new fields of research in theoretical and experimental physics. Read More


In this article, halfway between popularized exposition and historical account, some key moments in the development of atomic theory in its beginnings are discussed. In particular, the events and the major discoveries that have highlighted the discrete structure of the atom's energy levels are presented in their logical and chronological sequence, starting from early studies on the decomposition of light by prisms until the quantum theory. --- In questo articolo, a met\`a strada tra l'esposizione divulgativa e il resoconto storico, vengono affrontati alcuni momenti significativi dello sviluppo della teoria atomica ai suoi primordi. Read More


The torque-free motion of rigid body in gravitational field is analyzed. The coin lands on a soft surface (such as the palm of the hand) that allows no bouncing. The model assumes the coin as a rigid body with constant angular momentum vector in the body frame, and no air resistance. Read More


Quark Wars is an all-new, adventure style game. We recommended playing it outdoors. Quark Wars is modeled upon the outdoor game called Hungarian Number War, with notable influence from Star Wars, the American epic space saga. Read More


Advances in robotics and additive manufacturing have become game-changing for the prospects of space industry. It has become feasible to bootstrap a self-sustaining, self-expanding industry at reasonably low cost. Simple modeling was developed to identify the main parameters of successful bootstrapping. Read More


Classes started in the newly established Physics Department of Calcutta University Science College in 1916. Raman, Bose and Saha were three young members of the small physics faculty consisting of barely half a dozen faculty members. Within about one decade, three extraordinary discoveries came from these young men---Saha ionization equation in 1920, Bose statistics in 1924, Raman effect in 1928. Read More


Are dreidels fair? In other words, does the average dreidel have an equal chance of turning up any one of its four sides? To explore this hypothesis, three different dreidels were each spun hundreds of times with the number of occurrences of each side recorded. It was found that all three dreidels tested -- a cheap plastic dreidel, an old wooden dreidel, and a dreidel that came embossed with a picture of Santa Claus -- were not fair. Statistically, for each dreidel, some sides came up significantly more often than others. Read More


Claude Francis Milliet Dechales described the Coriolis effect in his 1674 Cursus seu Mundus Mathematicus. Dechales discussed and illustrated the deflection of both falling bodies and of projectiles launched toward the poles that should occur on a rotating Earth. Interestingly, this was done as an argument against the Earth's rotation, the deflections not having been observed at the time. Read More


We have been congratulated on the stage by a Nobel laureate (he was our curtain raiser), played our music in planetariums, museums, observatories throughout Spain and at the end of the meeting of the ESO telescopes time allocation committee, shocked audiences in rock concerts, written monthly on Musica Universalis, made the second concert in 3D in Spain after Kraftwerk and broadcasted it live in Radio 3, mixed our music with poetry read aloud by scientists, composed the soundtracks of CARMENES, QUIJOTE, ESTRACK and the Gaia first data release, made a videoclip on how computer simulates the formation of stars... Read More


This paper describes a system designed as part of an interactive VR opera, which immerses a real-time composer and an audience (via a network) in the historical location of Gobeklitepe, in southern Turkey during an imaginary scenario set in the Pre-Pottery Neolithic period (8500-5500 BCE), viewed by some to be the earliest example of a temple, or observatory. In this scene music is generated, where the harmonic material is determined based on observations of light variation from pulsating stars, that would have theoretically been overhead on the 1st of October 8000 BC at 23:00 and animal calls based on the reliefs in the temple. Based on the observations of the stars V465 Per, HD 217860, 16 Lac, BG CVn and KIC 6382916, frequency collections were derived and applied to the generation of musical sound and notation sequences within a custom VR environment using a novel method incorporating spectralist techniques. Read More


Whether the fate of our species can be forecast from its past has been the topic of considerable controversy. One refutation of the so-called Doomsday Argument is based on the premise that we are more likely to exist in a universe containing a greater number of observers. Here we present a Bayesian reformulation of the Doomsday Argument which is immune to this effect. Read More


A simple model is presented to explain the Higgs boson physics to the grand public. The model consists of a children ball pool representing a Universe filled with a certain amount of the Higgs field. The model is suitable for usage as a hands-on tool in scientific exhibits and provides a clear explanation of almost all the aspects of the physics of the Higgs field interaction with other particles. Read More


Summer 2015 marked the 100th anniversary of the excavation by J.W. Fewkes of the Sun Temple in Mesa Verde National Park, Colorado; an ancient ceremonial complex of unknown purpose, prominently located atop a mesa, constructed by the Pueblo Indians approximately 1000 years ago. Read More


We report an emergence of bifurcation in basketball, a single-particle system governed by Newtonian mechanics. When shooting the basketball, the obvious control parameters are the launch speed and the launch angle. We propose to use the three-dimensional velocity phase-space volume associated with the given launch parameters to quantify the difficulty of the shooting. Read More


The art of advertising one's scientific achievements, of which Galileo was an early master, is a trademark of successful modern science. Dedicated believers and mystics of science, such as Kepler, are less popular. Yet, an alleged rigorous rationalist like Wolfgang Pauli found in his later troubled life a kinship to Kepler's "archetypal ideas". Read More


Experiments are done by colliding a swinging bat with a stationary baseball or softball. Each collision was recorded with high-speed cameras, from which the post-impact speed, launch angle, and spin of the ball could be determined. Initial bat speeds were in the range 63-88 mph, producing launch angles in the range 0$^\circ$-30$^\circ$ and spins in the range 0-3500 rpm. Read More


We consider global catastrophic risks due to cosmic explosions (supernovae, magnetars and gamma-ray bursts) and possible mitigation strategies by humans and other hypothetical intelligent beings. While by their very nature these events are so huge to daunt conventional thinking on mitigation and response, we wish to argue that advanced technological civilizations would be able to develop efficient responses in the domain of astroengineering within their home planetary systems. In particular, we suggest that construction of shielding swarms of small objects/particles confined by electromagnetic fields could be one way of mitigating the risk of cosmic explosions and corresponding ionizing radiation surges. Read More


Sound measurements on a sequence of related, similar constructions with slightly different dimensions confirm a simple picture of the air modes of the internal resonator banjo's body. For the purpose of this study, the air modes are decoupled from the soundboard (i.e. Read More


We present a new teaching and outreach activity based around the construction of a three-dimensional chart of isotopes using LEGO$^{\circledR}$ bricks. The activity, \emph{Binding Blocks}, demonstrates nuclear and astrophysical processes through a seven-meter chart of all nuclear isotopes, built from over 26,000 LEGO$^{\circledR}$ bricks. It integrates A-level and GCSE curricula across areas of nuclear physics, astrophysics, and chemistry, including: nuclear decays (through the colours in the chart); nuclear binding energy (through tower heights); production of chemical elements in the cosmos; fusion processes in stars and fusion energy on Earth; as well as links to medical physics, particularly diagnostics and radiotherapy. Read More


Previous work has presented both a theoretical foundation for designing terrain park jumps that control landing impact and computer software to accomplish this task. US ski resorts have been reluctant to adopt this more engineered approach to jump design, in part due to questions of feasibility. The present study demonstrates this feasibility. Read More


This is a chapter for an upcoming book, "Space, Time, and the Limits of Human Understanding", edited by Shyam Wuppuluri and Giancarlo Ghirardi. I first present the classical picture of flat space and ever-flowing time, as generally accepted until about 1900, discuss the challenges posed by modern physics and the adjustments required by special relativity, general relativity and quantum mechanics, and finally consider (and reject) a recent hypothesis that space-time is essentially discrete. Ultimately, none of the simple answers to "what is space-time?" stand up to reality. Read More


Some European scholars in the second half of 18th century discussed the myth of Atlantis taking into account the studies of the evolution of the Earth and of the beginning and diffusion of civilization, in particular the beginning of astronomy. Atlantis was considered the cradle of the civilization, and while J.S. Read More


It is unclear how frequently life and intelligence arise on planets. I consider a Bayesian prior for the probability P(ETI) that intelligence evolves at a suitable site, with weight distributed evenly over ln(1 - ln P(ETI)). This log log prior can handle a very wide range of P(ETI) values, from 1 to 10^(-10^122), while remaining responsive to evidence about extraterrestrial societies. Read More


In this paper we examine more deeply about the bending mechanism of rod-shaped fireworks which burned from the free end. We derived new analytic equations. Surprisingly, we obtained the bending patterns are similar to the cornu spiral. Read More


The philosopher Plato is remembered even today by scientists, and his writings are still inspiring the scientific research. In the present short note (intended essentially for public outreach) two examples are briefly illustrated: 1) the European space project that bears his name, dedicated to the discovery of exoplanets; 2) the discussion about platonism in contemporary physics. Read More


The national space programs have an historic opportunity to help solve the global-scale economic and environmental problems of Earth while becoming more effective at science through the use of space resources. Space programs will be more cost-effective when they work to establish a supply chain in space, mining and manufacturing then replicating the assets of the supply chain so it grows to larger capacity. This has become achievable because of advances in robotics and artificial intelligence. Read More


The concept of a space elevator dates back to Tsilokovsky, but they are not commonly considered in near-term plans for space exploration, perhaps because a terrestrial elevator would not be possible without considerable improvements in tether material. A Lunar Space Elevator (LSE), however, can be built with current technology using commercially available tether polymers. This paper considers missions leading to infrastructure capable of shortening the time, lowering the cost and enhancing the capabilities of robotic and human explorers. Read More


The Zoo solution to Fermi's Paradox proposes that extraterrestrial intelligences (ETIs) have agreed to not contact the Earth. The strength of this solution depends on the ability for ETIs to come to agreement, and establish/police treaties as part of a so-called "Galactic Club". These activities are principally limited by the causal connectivity of a civilisation to its neighbours at its inception, i. Read More


Suppose that advanced civilizations, separated by a cosmological distance and time, wish to maximize their access to cosmic resources by rapidly expanding into the universe. What sort of boundary forms between their expanding domains, and how does the presence of one limit the ambitions of another? We describe a general case for any expansion speed, separation distance, and time. We then specialize to the main question of interest. Read More


In earlier papers, techniques have been described using optical chronographs to determine free flight drag coefficients with an accuracy of 1-2%, accomplished by measuring near and far velocities of projectiles in flight over a known distance. Until recently, Doppler radar has been prohibitively expensive for many users. This paper reports results of exploring potential applications and accuracy using a recently available, inexpensive (< $600 US) amateur Doppler radar system to determine drag coefficients for projectiles of various sizes (4. Read More


Science has traditionally played an important role in sharing knowledge among people. Particle Physics, with its large experiments, has shown that one not only can share the knowledge among different cultures, but that one can also work together to achieve this knowledge. The present article gives a few examples where this has been possible among people that are sometimes in conflict situations. Read More


We are at a stage in our evolution where we do not yet know if we will ever communicate with intelligent beings that have evolved on other planets, yet we are intelligent and curious enough to wonder about this. We find ourselves wondering about this at the very beginning of a long era in which stellar luminosity warms many planets, and by our best models, continues to provide equally good opportunities for intelligent life to evolve. By simple Bayesian reasoning, if, as we believe, intelligent life forms have the same propensity to evolve later on other planets as we had to evolve on ours, it follows that they will likely not pass through a similar wondering stage in their evolution. Read More