CyberSec Research

As a famous landmark and feat of engineering, the Gateway Arch was a popular destination at the 2025 AAPT Winter Meeting in St. Louis. The visit to the observation deck of the Gateway Arch is unique, climbing the steps after exiting the small tram capsules and seeing a floor that continues to slope upward assures that you are in fact at the very top. Everyone in our group excitedly took pictures, pointing out local features like the Dred Scott Courthouse. There were many selfies at the pinnacle, and we discussed how to work them into future questions for our students. During our tram ride to the top observation deck of the arch, we lamented that we should have brought pendula to measure the acceleration due to gravity. You can take physics teachers out of the physics conference, but you apparently can't get us to stop talking about physics teaching. Recognizing that we had accelerometers on our phones we collected data on the descent. The authors wanted to collect more complete measurements and returned two days later to repeat the journey, the results of which we present here. For readers wishing to repeat with their students, or who want to apply more advanced data analysis techniques, the authors have made the raw data, our spreadsheets, and a teacher's guide available.

The Deep Space Network (DSN) is the primary means of commanding, tracking, and receiving data from all of NASA's deep space missions, as well as a number of deep space missions operated by other international space agencies. The current number of missions enabled by the DSN is approximately 40 missions, but there has been concern about the level of "over-subscription" of the DSN, namely that the number of missions currently using the DSN is larger than can be enabled reasonably. This manuscript assesses the maximum number of missions that could be enabled, based on recent performance and with the constraint that the total number of hours used per week does not exceed the available number of DSN antenna-hours. Three different models are considered, and the maximal number of missions that could be enabled ranges between approximately 40 missions and 70 missions, assuming that there continues to be approximately six Mars missions and that those Mars missions continue to make use of the DSN's multiple spacecraft per antenna (MSPA) capability. Crucially, the conclusion that an approximately 50% growth in the DSN mission suite rests on the assumption that the DSN antennas are "interchangeable," but they are not, with some spacecraft able to use only certain antennas. Efforts to make the DSN antennas more "interchangeable," primarily in their transmitter and receiver suites, would be an effective means of ensuring expanded capability. Additional findings from this work are that, while additional use of the MSPA capability might appear to be a promising means for increasing the mission suite, there appear to be no locations in the Solar System, other than Mars, for which it would be effective.

The energy transition is also about switching to electricity-based technologies such as heat pumps and electric mobility. They avoid heat as an intermediate step and are therefore much more efficient. This can significantly reduce the demand for primary energy in the future, which can then be fully covered by the expansion of renewable energies. Entropy and the maximum possible combustion temperature can be used to understand why combustion is so inefficient.

On 2032 December 22 the 60 m diameter asteroid 2024 YR4 has a 4% chance of impacting the Moon. Such an impact would release 6.5 MT TNT equivalent energy and produce a ~1 km diameter crater. We estimate that up to 10^8 kg of lunar material could be liberated in such an impact by exceeding lunar escape speed. Depending on the actual impact location on the Moon as much as 10% of this material may accrete to the Earth on timescales of a few days. The lunar ejecta-associated particle fluence at 0.1 - 10 mm sizes could produce upwards of years to of order a decade of equivalent background meteoroid impact exposure to satellites in near-Earth space late in 2032. Our results demonstrate that planetary defense considerations should be more broadly extended to cis-lunar space and not confined solely to near-Earth space.

The emerging cryptocurrency market presents unique challenges for investment due to its unregulated nature and inherent volatility. However, collective price movements can be explored to maximise profits with minimal risk using investment portfolios. In this paper, we develop a technical framework that utilises historical data on daily closing prices and integrates network analysis, price forecasting, and portfolio theory to identify cryptocurrencies for building profitable portfolios under uncertainty. Our method utilises the Louvain network community algorithm and consensus clustering to detect robust and temporally stable clusters of highly correlated cryptocurrencies, from which the chosen cryptocurrencies are selected. A price prediction step using the ARIMA model guarantees that the portfolio performs well for up to 14 days in the investment horizon. Empirical analysis over a 5-year period shows that despite the high volatility in the crypto market, hidden price patterns can be effectively utilised to generate consistently profitable, time-agnostic cryptocurrency portfolios.

We present SeePhys, a large-scale multimodal benchmark for LLM reasoning grounded in physics questions ranging from middle school to PhD qualifying exams. The benchmark covers 7 fundamental domains spanning the physics discipline, incorporating 21 categories of highly heterogeneous diagrams. In contrast to prior works where visual elements mainly serve auxiliary purposes, our benchmark features a substantial proportion of vision-essential problems (75%) that mandate visual information extraction for correct solutions. Through extensive evaluation, we observe that even the most advanced visual reasoning models (e.g., Gemini-2.5-pro and o4-mini) achieve sub-60% accuracy on our benchmark. These results reveal fundamental challenges in current large language models' visual understanding capabilities, particularly in: (i) establishing rigorous coupling between diagram interpretation and physics reasoning, and (ii) overcoming their persistent reliance on textual cues as cognitive shortcuts.

Space exploration technology continues to expand humanity's reach beyond Earth, and even more ambitious efforts are striving to establish long-duration human settlements on Mars. The dependence of martian settlers on life-support infrastructure and on resupply missions from the host nation could create conditions for tyranny or lead to other extreme and uncontrollable situations, but such risks could be reduced by thinking about the possibilities for effective decision making on Mars before any settlement efforts actually occur. This paper examines the extent to which referendums could be used on Mars as a means of political decision-making and sovereignty adjudication. Our approach draws on three terrestrial case studies -- the Great Idaho Movement in the United States, the Catalan Independence Movement in Spain, and the Quebec Independence Movement in Canada -- as potential analogs for Mars governance. We recommend advance determination of the conditions under which a martian referendum would be recognized as a best practice for any agency seeking to establish a long-duration settlement on Mars. We suggest that referendums can reduce the likelihood of multiple authoritative political entities existing on Mars, which could provide a more procedural approach toward resolving governance issues between Earth and Mars. However, if Mars settlement is successful in establishing settlements on the scale of cities or larger, then other uniquely martian tools may evolve as a supplement or replacement to referendums.

The amazing quantum effect of `entanglement' was discovered in the 1935 thought experiment by Albert Einstein, Boris Podolsky and Nathan Rosen (`EPR'). The ensuing research opened up fundamental questions and led to experiments that proved that quantum theory cannot be completed by local hidden variables. Remarkably, EPR did not discuss how to create the entanglement in their thought experiment. Here I add this part. What is required in the original EPR thought experiment is a simple elastic particle collision, an unbalanced mass ratio of e.g. 1:3 and initial states that are position and momentum squeezed, respectively. In the limiting case of infinite squeeze factors, the measurement of the position or momentum of one particle allows an absolutely precise conclusion to be drawn about the value of the same quantity of the other particle. The EPR idea has never been tested in this way. I outline a way to do this.

Faz-se uma breve reconstru\c{c}\~ao hist\'orica de alguns pontos que, de algum modo, contribu\'iram para o trabalho seminal de Louis de Broglie. Em particular, enfatiza-se a relev\^ancia de sua tese de doutorado, principalmente por seu valor epistemol\'ogico, ao ampliar a crise que havia sido introduzida na descri\c{c}\~ao da radia\c{c}\~ao pelo \textit{quantum} de Planck, abrindo caminho para sua solu\c{c}\~ao. A brief historical reconstruction of some points that, in some way, contributed to Louis de Broglie's seminal work is made. In particular, the relevance of his doctoral thesis is emphasized, mainly for its epistemological value, in expanding the crisis that had been introduced in the description of radiation by Planck's quantum, paving the way for its solution.

This paper is a continuation of a series of works, devoted to various aspects of the 1908 Tunguska event. A large number of hypotheses about its causes have been put forward already. However, so far none of them has received convincing evidence. This is probably why new hypotheses appear almost every year, not only in the mass-media, but also in scientific literature. At the same time, any hypothesis should not contradict the known facts about the event. Unfortunately, the authors of new hypotheses, as well as the authors of popular science articles, often use data, many of which turned out to be not entirely accurate, or even incorrect. In this paper some of this data will be considered. Also the history of the Tunguska research is considered in this paper. Some other aspects of the 1908 Tunguska event are considered too.

Searching for extraterrestrial life and supporting human life in space are traditionally regarded as separate challenges. However, there are significant benefits to an approach that treats them as different aspects of the same essential inquiry: How can we conceptualize life beyond our home planet?

Black holes are the sources of the strongest gravitational fields that can be found today in the Universe and are ideal laboratories for testing Einstein's theory of General Relativity in the strong field regime. In this letter, I show that the possibility of an interstellar mission to send small spacecrafts to the nearest black hole, although very speculative and extremely challenging, is not completely unrealistic. Certainly we do not have the necessary technology today, but it may be available in the next 20-30 years. The mission may last 80-100 years, but we would be able to obtain very valuable information about black holes and General Relativity that could be unlikely obtained in other ways.

This paper offers educational insight into the Dirac equation, examining its historical context and contrasting it with the earlier Schr\"odinger and Klein-Gordon (KG) equations. The comparison highlights their Lorentz transformation symmetry and potential probabilistic interpretations. We explicitly solve the free-particle dynamics in Dirac's model, revealing the emergence of negative-energy solutions. This discussion examines the Dirac Sea Hypothesis and explores the solutions' inherent helicity. Additionally, we demonstrate how the Dirac equation accounts for spin and derive the Pauli equation in the non-relativistic limit. The Foldy-Wouthuysen transformation reveals how the equation incorporates spin-orbit interaction and other relativistic effects, ultimately leading to the fine structure of hydrogen. A section on relativistic covariant notation is included to emphasize the invariance of the Dirac equation, along with more refined formulations of both the KG and Dirac equations. Designed for undergraduate students interested in the Dirac equation, this resource provides a historical perspective without being purely theoretical. Our approach underscores the significance of a pedagogical method that combines historical and comparative elements to profoundly understand the role of the Dirac equation in modern physics.

Understanding quantum mechanics is inherently challenging due to its counterintuitive principles. Quantum Intuition XR is an interactive, extended reality (XR) experience designed to make quantum concepts tangible. Our system visualizes core principles of quantum computing, including qubits, superposition, entanglement, and measurement, through immersive interaction. Using a Mixed Reality headset, participants engage with floating qubits, manipulate their states via controllers, and observe entanglement dynamics through real-time audiovisual feedback. A key feature of our implementation is the mathematically accurate and dynamic representation of qubits, both individually and while interacting with each other. The visualization of the qubit states evolve -- rotate, shrink, grow, entangle -- depending on their actual quantum states, which depend on variables such as proximity to other qubits and user interaction. Preliminary expert interviews and demonstrations with quantum specialists indicate that the system accurately represents quantum phenomena, suggesting strong potential to educate and enhance quantum intuition for non-expert audiences. This approach bridges abstract quantum mechanics with embodied learning, offering an intuitive and accessible way for users to explore quantum phenomena. Future work will focus on expanding multi-user interactions and refining the fidelity of quantum state visualizations.

We assess how physically realistic the ''simulation hypothesis'' for this Universe is, based on physical constraints arising from the link between information and energy, and on known astrophysical constraints. We investigate three cases: the simulation of the entire visible Universe, the simulation of Earth only, or a low resolution simulation of Earth, compatible with high-energy neutrino observations. In all cases, the amounts of energy or power required by any version of the simulation hypothesis are entirely incompatible with physics, or (literally) astronomically large, even in the lowest resolution case. Only universes with very different physical properties can produce some version of this Universe as a simulation. On the other hand, our results show that it is just impossible that this Universe is simulated by a universe sharing the same properties, regardless of technological advancements of the far future.

In Szilard's engine, a demon measures a one-particle gas and applies feedback to extract work from thermal fluctuations, embodying Maxwell's notion that information reduces thermodynamic entropy - an apparent second-law violation. The Landauer-Bennett Thesis resolves this paradox by requiring the demon to record the measurement, which results in an entropy increase in the demon's memory. Eventually, the demon's memory needs to be erased. The erasure costs the same work as extracted previously, hence there is no violation of the second law. Though widely accepted, the fictitious memory invoked in the thesis has drawn multiple criticisms, with debates persisting over the demon's necessity. We show that the demon is the piston that partitions the space and drives the expansion. The final position of the piston after expansion records the particle's position pre-expansion: it is an ``information-bearing degree of freedom''. In this Piston-Demon Thesis, memory register and feedback (expansion) happen simultaneously. Our exposition identifies the mischievous demon as a physical degree of freedom, and greatly simplifies Szilard's engine. It also offers educators a tangible illustration of information-thermodynamics.

In the production of modern music, the musical characteristics of the guitar or keyboard amplifier play an integral role in the creative process. This article explores the physics of music with an emphasis on the role of distortion in the amplification. In particular, we derive and illustrate how a distorted amplifier creates new musical notes that are not played by the musician, greatly simplifying the playing technique. In providing a comprehensive understanding, we commence with a discussion of the physics of music, highlighting the harmonic series and its relation to pleasing harmonies. This is placed in the context of the standard music notation of intervals and their relation to note frequency ratios. We then discuss the problems of tuning an instrument and why the equal temperament of standard guitar tuners is incompatible with good sounding music when amplifier distortion is involved. Drawing on the basic trigonometric identities for angle sums and differences, we show how the nonlinear amplification of a distorted amplifier, generates new notes not played by the musician. Here the importance of setting your guitar tuner aside and using your ear to tune is emphasised. We close with a discussion of how humans decipher musical notes and why some highly distorted guitar chords give the impression of low notes that are not actually there. This article will be of assistance to students interested in the physics of music and lecturers seeking fascinating and relevant applications of mathematical trigonometric relations and physics to capture the attention of their students.

The spherical cow approximation is widely used in the literature, but is rarely justified. Here, I propose several schemes for extending the spherical cow approximation to a full multipole expansion, in which the spherical cow is simply the first term. This allows for the computation of bovine potentials and interactions beyond spherical symmetry, and also provides a scheme for defining the geometry of the cow itself at higher multipole moments. This is especially important for the treatment of physical processes that are suppressed by spherical symmetry, such as the spindown of a rotating cow due to the emission of gravitational waves. I demonstrate the computation of multipole coefficients for a benchmark cow, and illustrate the applicability of the multipolar cow to several important problems.