Searcharxiv⌕ Search

SEARCH · Searcharxiv

Results for “physics.pop-ph”

Search indexed arXiv papers on artificial intelligence, large language models, computer vision and robotics. Read source abstracts and follow links to arXiv.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35Linked to original sources
arXiv2023

The Draconic gearing of the Antikythera Mechanism: Assembling the Fragment D, its role and operation

The unplaced Fragment D of the Antikythera Mechanism with an unknown operation was a mystery ever since it was discovered. The gear r1, which was detected in Fragment D radiographies by C. Karakalos is preserved in excellent condition but this was not enough to directly relate it to the existing gear trains of the Mechanism. The suggestion that Fragment D could be a part of the hypothetical planet indication gearing is a hypothesis, in contradiction with the AMRP tomographies, and leads to mechanical malfunctions. The analysis of AMRP tomographies of Fragment D and its mechanical characteristics, revealed that it could be part of the Draconic gearing. Currently, the three lunar cycles Synodic, Sidereal and Anomalistic are represented on the Antikythera Mechanism. Although the Draconic cycle was well known during the Mechanism era as representing the critical fourth Lunar cycle, it seems that it is missing from the Antikythera Mechanism. The study of Fragment D was supported by our bronze reconstructions of the Fragment D, leading to the reconstruction of the Draconic gearing. These results are very important, because with the use of only one hypothetical,missing gear, the Draconic gearing is revealed on the Antikythera Mechanism. Fragment D(raconic) can be perfectly correlated with the Draconic cycle of the Antikythera Mechanism without mechanical problems and the four lunar cycles appear on the Mechanism. Based on the Draconic pointer, the eclipse events can be calculated and engraved on the Saros spiral cells.

physics.pop-ph↗
arXiv2021

Combined Airborne Wind and Photovoltaic Energy System for Martian Habitats

Generating renewable energy on Mars is technologically challenging. Firstly, because compared to Earth, key energy resources such as solar and wind are weak as a result of very low atmospheric pressure and low solar irradiation. Secondly, because of the harsh environmental conditions, the required high degree of automation and the exceptional effort and costs to transport material to the planet. Like on Earth, it is crucial to combine complementary resources for an effective renewable energy solution. In this work, we present the result of a design synthesis exercise, a 10 kW microgrid solution, based on a pumping kite power system and photovoltaic solar modules to power the construction as well as the subsequent use of a Mars habitat. To buffer unavoidable energy fluctuations and balance seasonal and diurnal resource variations, the two energy systems are combined with a compressed gas storage system and lithium-sulfur batteries. The airborne wind energy solution was selected because of its low weight-to-wing-surface-area ratio, compact packing volume and high capacity factor which enables it to endure strong dust storms in an airborne parking mode. The surface area of the membrane wing is 50 m2 and the mass of the entire system, including the kite control unit and ground station, is 290 kg. The performance of the microgrid is assessed by computational simulation using available resource data for a chosen deployment location on Mars. The projected costs of the system are 8.95 million Euro, excluding transportation to Mars.

astro-ph.IM↗
arXiv2021

The Drake Equation at 60: Reconsidered and Abandoned

Each of the individual factors of the Drake Equation is considered. Each in turn is either abandoned or redefined and finally reduced to a single new factor, fd, the fraction of technological life that is detectable by any means. However, neither the Drake Equation, nor its replacement, can actually solve for N. Only a vibrant SETI program and, ultimately, contact with an alien civilization might result in the determination of N.

physics.pop-ph↗
arXiv2021

But, how can the atom be so stable, Dr. Maxwell?

In the initial stages of its development, atomic theory had to bypass the laws of classical electromagnetism in an ad hoc manner in order to explain the stability of atoms. In quantum mechanics, however, the classical theory may find again some room even for a microscopic structure such as the atom. Provided, of course, that certain classical concepts are reexamined and suitably reinterpreted...

physics.pop-ph↗
arXiv2025

Thrust based on changes in angular momentum

A novel non-reactive thrust principle based on controlling the angular momentum of a material body is proposed. Theoretically, it is shown that asymmetric emission/absorption of low-energy particle fluxes with spin in a direction perpendicular to the motion enables the creation of a propulsion system whose energy efficiency exceeds that of a photon engine by several orders of magnitude near massive bodies. Using the example of a "dumbbell-flywheel" system dynamics in a central gravitational field, the possibility of controlling orbital parameters without propellant consumption is demonstrated. Experiments in a vacuum chamber revealed anomalies consistent with the hypothesis of spacetime spin polarization. The developed approach offers a mechanistic interpretation of wave-particle duality and suggests new pathways for unifying gravity with quantum mechanics. The obtained results open prospects for the development of next-generation propulsion systems.

physics.pop-ph↗
arXiv2021

Technoeconomic Analysis of Thermal Energy Grid Storage Using Graphite and Tin

Energy storage is needed to enable dispatchable renewable energy supply and thereby full decarbonization of the grid. However, this can only occur with drastic cost reductions compared to current battery technology, with predicted targets for the cost per unit energy (CPE) below $20/kWh. Notably, for full decarbonization, long duration storage up to 100 hrs will be needed at such low costs, and prior analyses have shown that in such high renewable penetration scenarios, CPE is more critical than other parameters such as round trip efficiency or cost per unit power when comparing the costs of different technologies. Here, we introduce an electricity storage concept that stores electricity as sensible heat in graphite storage blocks and uses multi-junction thermophotovoltaics (TPV) as a heat engine to convert it back to electricity on demand. This design is an outgrowth of the system proposed by Amy et al. in 2019, which has been modified here to use a solid graphite medium and molten tin as a heat transfer fluid rather than silicon as both. The reason for this is two-fold: (1) the CPE of graphite is almost 10X lower than that of silicon, which derives from the lower cost per unit mass (i.e., $0.5/kg vs. $1.5/kg) and the higher heat capacity per unit mass (2000 J/kg-K vs. 950 J/kg-K); and (2) the melting point tin and solubility of tin in graphite are much lower than that of silicon, which lessens the number of issues that have to overcome along the research and development pathway. The usage of graphite also eliminates the need for a second tank, but the main disadvantage of using a solid medium is that one cannot easily provide a steady discharge rate, as the power output from the storage will change with time, as the graphite cools during discharge. Thus, the objective of this work is to examine how these changes in the system design effect the overall technoeconomics.

physics.app-ph↗
arXiv2021

The spinor linkage -- a mechanical implementation of the plate trick

The plate trick or belt trick is a striking physical demonstration of properties of the double cover of the three-dimensional rotation group by the sphere of unit quaternions or spinors. The two ends of a flexible object are continuously rotated with respect to each other. Surprisingly, the object can be manipulated so as to avoid accumulating twists. We present a new mechanical linkage that implements this task. It consists of a sequence of rigid bodies connected by hinge joints, together with a purely mechanical control mechanism. It has one degree of freedom, and the motion is generated by simply turning a handle.

physics.pop-ph↗
arXiv2022

The Voronoi Diagram in Soccer: a theoretical study to measure dominance space

In this article, I argue that the concept of the standard Voronoi diagram is incorrect for the calculation of dominance area in soccer. The correct region that should replace the polygonal Voronoi region controlled by a player emerges naturally by studying the motion of the players. It turns out that the widely-used standard Voronoi diagram is true only when all 22 players have the same speed (with vanishing speed being a special case) and it should be replaced by other diagrams whose regions have more complicated boundaries. The unfortunate error happened when the mathematical concept of the Voronoi diagram that has an implicit vanishing speed for its points was transferred to soccer without looking at the kinematical issues involved in the game of soccer. For this reason, as a byproduct of this work, I argue for the promotion of "soccerdynamics", model building for soccer by looking at the underlying mechanisms and not just adopting mathematical ideas only for their appeal and beauty.

physics.soc-ph↗
arXiv2021

Limits of Detecting Extraterrestrial Civilizations

The search for extraterrestrial intelligence (SETI) is a scientific endeavor which struggles with unique issues -- a strong indeterminacy in what data to look for and when to do so. This has led to attempts at finding both fundamental limits of the communication between extraterrestrial intelligence and human civilizations, as well as benchmarks so as to predict what kinds of signals we might most expect. Previous work has been formulated in terms of the information-theoretic task of communication, but we instead argue it should be viewed as a detection problem, specifically one-shot (asymmetric) hypothesis testing. With this new interpretation, we develop fundamental limits as well as provide simple examples of how to use this framework to analyze and benchmark different possible signals from extraterrestrial civilizations. We show that electromagnetic signaling for detection requires much less power than for communication, that detection as a function of power can be non-linear, and that much of the analysis in this framework may be addressed using computationally efficient optimization problems, thereby demonstrating tools for further inquiry.

cs.IT↗
arXiv2021

Intelligent Responses to Our Technological Signals Will Not Arrive In Fewer Than Three Millennia

What is the chance we start a conversation with another civilization like our own? Our technological society produced signals that could be received by other extraterrestrial civilizations, within a sphere around us with a radius of $\sim 10^2$ light years. Given that, the Copernican principle provides a lower limit on the response time that we should expect from transmitters on Earth-like planets around Sun-like stars. If our civilization lives longer, the expected number of responses could increase. We explore the chance of detecting a response in the future, and show that a response should only be expected to arrive after a few millennia.

physics.pop-ph↗
arXiv2021

Can China's FAST telescope detect extraterrestrial von-Neumann probes?

In the present paper we consider the Type-2.x and Type-3.x extraterrestrial von-Neumann probes and study the problem of their detectability by the world's largest radio telescope: the Five-hundred-meter Aperture Spherical Radio Telescope (FAST). For this purpose we estimate the radio spectral parameters and analyse the obtained results in the context of technical characteristics of FAST. As a result, it is shown that FAST can detect as galactic as well as extragalactic self-replicating probes with high precision.

physics.pop-ph↗
arXiv2021

An initial review of hypersonic vehicle accidents

Hypersonic flight, generally defined as the region in which the speed of a vehicle exceeds Mach 5 and in which thermal loads become dominant, has seen more attention over the past several decades due to the potential military applications of such vehicles. Vehicles capable of flight at these speeds, whilst seemingly a novel prospect, have been in development for more than 70 years. The nature of flight in this environment as well as the new challenges it introduces have led to relatively high failure rates. This paper presents a review of hypersonic vehicle flights that have resulted in failure from conception to modern day with the purpose of identifying trends to aid and guide the development of future vehicles. The collected data is used to formulate a failure taxonomy to accurately identify and classify past hypersonic vehicle failures as well as potential future ones. The trends and features of the categorical data collected are explored using an ex-post facto study.

physics.soc-ph↗
arXiv2021

Feasibility Study For Hydrogen Producing Colony on Mars

A technologically mature colony on Mars can produce and deliver at least 1 million tons of liquid hydrogen per year to one or more propellant depots at Low Earth Orbit (LEO). Production of 1 $kg$ of hydrogen at Marian colony and its delivery to LEO requires an energy expenditure of 1.4 $GJ$ on Mars. LEO propellant depot contains hydrogen produced on Mars and oxygen produced on the Moon or near-Earth asteroids. This propellant is used to deliver payload from LEO to many destinations in the Solar System including Mars. Delivery of 1 $kg$ payload from LEO to Mars requires an energy expenditure of 3.5 $GJ$ on Mars, Moon, and near-Earth asteroids. The use of liquid hydrogen produced on Mars to deliver astronauts and payload to Mars ensures exponential bootstrap growth of the Martian colony. Martian Colony and delivery of millions of tons of liquid hydrogen to LEO is the key to Colonization of Solar System. %% Martian Colony starts transporting liquid hydrogen to LEO only after it grows to significant size. It should contain about 20 million tons of steel and 3 million tons of plastic in structures and material as well as several thousand astronauts. Prior to that time, LEO hydrogen deposit will be supplied by hydrogen from Lunar poles.

physics.pop-ph↗
arXiv2023

The Search for Deliberate Interstellar SETI Signals May Be Futile

For more than 60 years, the predominant SETI search paradigm has entailed the observation of stars in an effort to detect alien electromagnetic signals that deliberately target Earth. However, this strategy is fraught with challenges when examined from ETs perspective. Astronomical, physiological, psychological, and intellectual problems are enumerated. Consequently, ET is likely to attempt a different strategy in order to best establish communications. It will send physical AI robotic probes that would be linked together by a vast interstellar network of communications nodes. This strategy would solve most or all problems associated with interstellar signaling.

physics.pop-ph↗
arXiv2021

Guided Self Replicating Factory for Colonization of Solar System

In this work we present the concept of guided self-replicating factory (GSFR). This factory would be established as a colony on the Moon, Mercury, Mars, or Asteroid Belt. GSFR would grow by using in situ materials in order to manufacture machines. The time it takes for GSFR to double it's mass and electric power output is called a doubling period. After about 50 doubling periods, GSFR would become a Dyson Sphere civilization, which can house $10^{16}$ people, $10^{19}\ tons$ of structure and machinery and have a gross electric power of $3 \cdot 10^{24}\ W$. GSRF would contain four parts. Electric power station would generate electricity for all other parts. Material production system would gather ores or native metals and produce metals, plastic, and propellant. Material shaping and assembly system would shape metal and plastic into details. These details would be assembled into machines. These machines would be added to all four parts of GSFR. Space transportation system would use fuel manufactured in situ manufactured in situ in order to facilitate transportation of machinery and astronauts from Lower Earth Orbit (LEO) to the colony. During later stages, space transportation system would also use spaceships fully or partially manufactured from space colony material.

physics.pop-ph↗