Latest Preprints

Timekeeping is often treated as a purely technological matter, delegated to clocks, computers, and the legal codes that regulate civil time. Yet the fundamental meanings of “day,” “noon,” and “the current time” are grounded in astronomy: Earth’s rotation, Earth’s orbital motion, and the geometric conventions of celestial coordinates. This article develops a unified set of lecture notes on three closely connected notions of time: sidereal time (star time), universal time (world time), and zone time (regional time). We begin by explaining why sidereal time is the natural clock for describing Earth’s rotation relative to the celestial sphere, and why its operational determination via meridian transits is both conceptually simple and historically central to astrometry. We then turn to solar time and the motivations for adopting mean solar time in civil life, highlighting the equation of time and the geometric and dynamical origins of seasonal variations between apparent and mean solar time. Next, we present the modern family of Universal Time realizations (UT0, UT1, and UT2), emphasizing the physical causes of irregularities in Earth rotation: tidal friction, long-term redistribution of mass, polar motion, and stochastic fluctuations. Finally, we discuss time zones and decree time as pragmatic social infrastructures that reconcile local astronomical time with the demands of transportation, administration, and energy policy. Throughout, we distinguish dynamical time from rotation-based time scales, and we clarify how contemporary atomic timekeeping reshaped the practical role of older astronomical scales. The result is a coherent framework that connects celestial geometry, Earth system physics, and civil conventions into a single account of “what time it is,” and why that question has multiple correct answers depending on context.

This paper presents a comprehensive history of the universe from the Big Bang to the present, with a special focus on the development of cosmology as a natural science. We examine the fundamental properties of the universe - its homogeneity, expansion, and space-time structure - and how these features were shaped by cosmic inflation. The paper discusses in detail the cosmological applications of general relativity, presenting solutions to the Friedmann-Einstein equations for different types of matter. Special attention is paid to the horizon problem and the inflationary model that solves it, which explains the observed symmetry and flat geometry of the universe. We analyze the cosmological role of different forms of matter - radiation, ordinary matter, and scalar fields - and show how these "types of matter" have replaced each other at different times in the history of the universe. The aim of the study is to present the results of today's precise cosmology, with a special emphasis on how cosmology has transformed from a speculative field into an exact natural science over the past two decades.

This paper presents a comprehensive history of the universe from the Big Bang to the present, with a special focus on the development of cosmology as a natural science. We examine the fundamental properties of the universe - its homogeneity, expansion, and space-time structure - and how these features were shaped by cosmic inflation. The paper discusses in detail the cosmological applications of general relativity, presenting solutions to the Friedmann-Einstein equations for different types of matter. Special attention is paid to the horizon problem and the inflationary model that solves it, which explains the observed symmetry and flat geometry of the universe. We analyze the cosmological role of different forms of matter - radiation, ordinary matter, and scalar fields - and show how these "types of matter" have replaced each other at different times in the history of the universe. The aim of the study is to present the results of today's precise cosmology, with a special emphasis on how cosmology has transformed from a speculative field into an exact natural science over the past two decades.

This paper presents a comprehensive history of the universe from the Big Bang to the present, with a special focus on the development of cosmology as a natural science. We examine the fundamental properties of the universe - its homogeneity, expansion, and space-time structure - and how these features were shaped by cosmic inflation. The paper discusses in detail the cosmological applications of general relativity, presenting solutions to the Friedmann-Einstein equations for different types of matter. Special attention is paid to the horizon problem and the inflationary model that solves it, which explains the observed symmetry and flat geometry of the universe. We analyze the cosmological role of different forms of matter - radiation, ordinary matter, and scalar fields - and show how these "types of matter" have replaced each other at different times in the history of the universe. The aim of the study is to present the results of today's precise cosmology, with a special emphasis on how cosmology has transformed from a speculative field into an exact natural science over the past two decades.

The concept of antigravity has fascinated humanity for centuries, from science fiction to practical applications. This paper analyzes the theoretical possibilities and practical limitations of antigravity effects through a comprehensive examination of the nature of gravity. Starting from the limitations of Newtonian gravity, we examine the mechanisms by which gravity can be counteracted or controlled within the framework of Einstein's general theory of relativity. We present various levitation and flight techniques, distinguishing them from true antigravity effects. We discuss in detail the special properties of the Higgs field, which according to general relativity can produce true antigravity effects. We demonstrate through the examples of cosmic inflation and domain walls that antigravity is a real physical phenomenon that has played an important role in the history of the universe. Although antigravity is theoretically possible, its practical application still faces significant challenges. The study highlights that while antigravity effects can occur under special circumstances, they cannot be applied to the realization of floating vehicles or means of transportation in the traditional sense.

This paper provides an overview of the concept of intelligence and the field of psychometrics from both a historical and quantitative perspective. Drawing on lecture material and expanded with mathematical formulations and R-based analytical scripts, we discuss the origins of intelligence testing, standardization, reliability and validity of psychometric instruments, and controversies surrounding the measurement and interpretation of intelligence. Real-world examples and illustrative data are used to clarify core concepts.

This article explores the fundamental relationship between genes, brain structure, and behavior in advanced cross-cultural psychology. We examine how modern neuroscience has established that the mind emerges from brain function, challenging traditional Cartesian dualism through evidence from brain imaging, lesion studies, and split-brain research. The discussion covers key anatomical features of the brain, including cortical organization and white matter pathways, and their functional significance. We analyze the historical development of neuroscientific understanding from Ramon y Cajal's pioneering neuronal illustrations to contemporary findings on localized brain functions. The article demonstrates how elementary processing units in the brain work through both serial and parallel mechanisms to generate complex behaviors. Additionally, we explore the genetic foundations of behavior, emphasizing that while genes influence neural architecture, environmental factors through epigenetic mechanisms also play crucial roles. Case studies including split-brain patients and real-time brain mapping during surgery illustrate the immediate relationship between neural activity and behavioral output. Finally, we examine circadian rhythm genes as an example of evolutionary conservation, showing how identical genetic mechanisms control sleep-wake cycles across species from bacteria to humans, highlighting both the biological unity of life and the specific adaptations that distinguish human cognition.

This comprehensive study examines the integration of machine learning technologies in contemporary healthcare environments.