Fundamental Physical Theories Research Articles

The Observer Concept in Science as a Basis for Its Further Curricular Application Within the Discipline-Culture Paradigm

AbstractThis study considers the concept of observer-the fundamental concept axial for fundamental physical theories. The history of the observer concept in physics is reviewed and summarized. In the following, the observer concept is considered with regard to science education where scientific concepts should reflect their status in science. This parallelism between science and education is epistemological and dynamic. The examination of the school curriculum reveals invalid correspondence in the case of the observer. The curriculum often presents the observer when addressing the Galileo principle of relativity, while frequently missing relativity of motion in presenting natural phenomena. Multiple observers are avoided in dynamics where the modern epistemology—drawing on a “local observer”—introduces non-inertial observers (inertial forces) currently banned in school physics. The article refines the possible curricular changes with respect to dynamics and kinematics which emphasize multiple observers. The suggested curricular changes could provide science learners with a new perspective on physics knowledge within the paradigm of multiple observers—cultural content knowledge of the subject matter.

LiteBIRD and CMB-S4 sensitivities to reheating in plateau models of inflation

We study the sensitivity of LiteBIRD and CMB-S4 to the reheating temperature and the inflaton coupling in three types of plateau-potential models of inflation, namely mutated hilltop inflation, radion gauge inflation, and α-attractor T models. We first find relations between model parameters and CMB observables in all models. We then perform Monte Carlo Markov Chain based forecasts to quantify the information gain on the reheating temperature, the inflaton coupling, and the scale of inflation that can be achieved with LiteBIRD and CMB-S4, assuming a fiducial tensor-to-scalar ratio r̅ ∼ 0.02 and neglecting foreground contamination of the B-mode polarization spectrum. We compare the results of the forecasts to those obtained from a recently proposed simple analytic method. We find that both LiteBIRD and CMB-S4 can simultaneously constrain the scale of inflation and the reheating temperature in all three types of models. They can for the first time obtain both an upper and lower bound on the latter, comprising the first ever measurement of the big bang temperature. In the mutated hilltop inflation and radion gauge inflation models this can be translated into a measurement of the inflaton coupling in parts of the parameter space. Constraining this microphysical parameter will help to understand how these models of inflation may be embedded into a more fundamental theory of particle physics.

Fundamental physics studies in time domain and multi-messenger astronomy

The era of ime domain and multi-messenger astronomy is not only leading to the development of a much broader set of detectors and instruments for astrophysical observations, but is also providing the means for astronomy to tie directly to cutting-edge studies in physics. In this manner, fundamental physics (theory and experiment) coupled with a strong theoretical understanding of astrophysical phenomena (guided by high-performance computing simulations) can tie directly to the amazing new observations in astronomy. This paper discusses how physics, astrophysical models, and observations can not only help astronomy probe fundamental physics but guide the needs for next-generation astrophysical missions.

MORALITY AND RELIGION IN THE CONTEXT OF THE RELATIONAL PARADIGM: CONSEQUENCES FOR SOCIAL IDEOLOGY

It is shown that the problem of the source and essence of morality is most satisfactorily solved on the basis of the metaphysics of Platonism. Its concrete implementation in the form of a fundamental physical theory is the relational paradigm of theoretical physics. A number of consequences have been developed from the interpretation of morality as a transcendent connection of a person with the First Cause of being for religious philosophy and social ideology.

Quantum reference frames: derivation of perspective-dependent descriptions via a perspective-neutral structure

In standard quantum mechanics, reference frames are treated as abstract entities. We can think of them as idealized, infinite-mass subsystems which decouple from the rest of the system. In nature, however, all reference frames are realized through finite-mass systems that are subject to the laws of quantum mechanics and must be included in the dynamical evolution. A fundamental physical theory should take this fact seriously. In this paper, we further develop a symmetry-inspired approach to describe physics from the perspective of quantum reference frames. We find a unifying framework allowing us to systematically derive a broad class of perspective dependent descriptions and the transformations between them. Working with a translational-invariant toy model of three free particles, we discover that the introduction of relative coordinates leads to a Hamiltonian structure with two non-commuting constraints. This structure can be said to contain all observer-perspectives at once, while the redundancies prevent an immediate operational interpretation. We show that the operationally meaningful perspective dependent descriptions are given by Darboux coordinates on the constraint surface and that reference frame transformations correspond to reparametrizations of the constraint surface. We conclude by constructing a quantum perspective neutral structure, via which we can derive and change perspective dependent descriptions without referring to the classical theory. In addition to the physical findings, this work illuminates the interrelation of first and second class constrained systems and their respective quantization procedures.

The irreversibility of relativistic time-dilation

The fluctuation relations, which characterize irreversible processes in nature, are among the most important results in non-equilibrium physics. In short, these relations say that it is exponentially unlikely for us to observe a time-reversed process and, thus, establish the thermodynamic arrow of time pointing from low to high entropy. On the other hand, fundamental physical theories are invariant under time-reversal symmetry. Although in Newtonian and quantum physics the emergence of irreversible processes, as well as fluctuation relations, is relatively well understood, many problems arise when relativity enters the game. In this work, by considering a specific class of spacetimes, we explore the question of how the time-dilation effect enters into the fluctuation relations. We conclude that a positive entropy production emerges as a consequence of both the special relativistic and the gravitational (enclosed in the equivalence principle) time-dilation effects.

Quantum simulation of non-Born–Oppenheimer dynamics in molecular systems by path integrals

A numerical algorithm based on the probabilistic path integral approach for solving Schrödinger equation has been devised to treat molecular systems without Born–Oppenheimer approximation in the nonrelativistic limit at zero temperature as an alternative to conventional variational and perturbation methods. Using high-quality variational trial functions and path integral method based on generalized Feynman–Kac method, we have been able to calculate the non-Born–Oppenheimer energy for hydrogen molecule for the [Formula: see text] state and hydrogen molecular ion. Combining these values and the value for ionization potential for atomic hydrogen, the dissociation energy and ionization potential for hydrogen molecules have been determined to be 36 113.672(3)[Formula: see text]cm[Formula: see text] and 124 446.066(10)[Formula: see text]cm[Formula: see text], respectively. Our results favorably compare with other theoretical and experimental results and thus show the promise of being a nonperturbative alternative for testing fundamental physical theories.

Nonequilibrium phases of ultracold bosons with cavity-induced dynamic gauge fields

Gauge fields are a central concept in fundamental theories of physics, and responsible for mediating long-range interactions between elementary particles. Recently, it has been proposed that dynamical gauge fields can be naturally engineered by photons in composite, neutral quantum gas-cavity systems using suitable atom-photon interactions. Here we comprehensively investigate nonequilibrium dynamical phases appearing in a two-leg bosonic lattice model with leg-dependent, dynamical complex tunnelings mediated by cavity-assisted two-photon Raman processes. The system constitutes a minimal dynamical flux-lattice model. We study fixed points of the equations of motion and their stability, the resultant dynamical phase diagram, and the corresponding phase transitions and bifurcations. Notably, the phase diagram features a plethora of nonequilibrium dynamical phases including limit-cycle and chaotic phases. In the end, we relate regular periodic dynamics (i.e., limit-cycle phases) of the system to time crystals.

Probing time orientability of spacetime

In general relativity, cosmology and quantum field theory, spacetime is assumed to be an orientable manifold endowed with a Lorentz metric that makes it spatially and temporally orientable. The question as to whether the laws of physics require these orientability assumptions is ultimately of observational or experimental nature, or the answer might come from a fundamental theory of physics. The possibility that spacetime is time non-orientable lacks investigation, and so should not be dismissed straightaway. In this paper, we argue that it is possible to locally access a putative time non-orientability of Minkowski empty spacetime by physical effects involving quantum vacuum electromagnetic fluctuations. We set ourselves to study the influence of time non-orientability on the stochastic motions of a charged particle subject to these electromagnetic fluctuations in Minkowski spacetime equipped with a time non-orientable topology and with its time orientable counterpart. To this end, we introduce and derive analytic expressions for a statistical time orientability indicator. Then we show that it is possible to pinpoint the time non-orientable topology through an inversion pattern displayed by the corresponding orientability indicator, which is absent when the underlying manifold is time orientable.

Representation of the universe as dendrogramic hologram empowered with relational interpretation

This is a brief review on the basics of recently established Dendrogramic Holographic theory (DH-theory). This is the special model of the event-universe based on the clustering transformation of experimental data into dendrogram, a finite tree which branches encoding the events. These event-branches are coupled via the hierarchic interrelation determined by the dendrogram. Such relational universe differs from the universe with space-time mathematically described by the real numbers. Dendrogram is endowed with the common root ultrametric. Finite dendrograms correspond to the epistemic level of description; in the limit we obtain an infinite tree providing the ontic description. In the simplest model, the tree is homogeneous, p-adic tree. It can be endowed with the algebraic structure of the ring of p-adic integers. Hence, DH-theory is a part (but very special) of p-adic theoretical physics. In this paper we discuss the foundations of DH-theory and its applications to quantum-classical interrelation including the novel interpretation of the violations of the CHSH-inequality, to general relativity, and to emergence of quantum mechanics from the event-picture of the universe. Since both quantum theory and general relativity can be emergent from DH-theory, creation of the latter can be viewed as a step towards unification of these two fundamental physical theories.

Barren Worlds

Abstract This work explores issues with the eliminativist formulation of ontic structural realism. An ontology that totally eliminates objects is found lacking by arguing, first, that the theoretical frameworks used to support the best arguments against an object-oriented ontology (quantum mechanics, relativity theory, quantum field theory) can be seen in every case as physical models of empty worlds, and therefore do not represent all the information that comes from science, and in particular from fundamental physics, which also includes information about local interactions between objects. Secondly, by giving a critical assessment of the role of symmetries in these fundamental physical theories; and, lastly, by warning about unfounded metaphysical assumptions. An argument is made for a moderate form of structural realism instead, one in which objects play the fundamental role of representing symmetries and bearing their conserved charges, and of participating in the network of interactions observed in the world.

Hunting Quantum Gravity with Analogs: The Case of Graphene

Analogs of fundamental physical phenomena can be used in two ways. One way consists in reproducing specific aspects of the classical or quantum gravity of quantum fields in curved space or of other high-energy scenarios on lower-energy corresponding systems. The “reverse way” consists in building fundamental physical theories, for instance, quantum gravity models, inspired by the lower-energy corresponding systems. Here, we present the case of graphene and other Dirac materials.

TO THE METHOD OF STUDYING THE BASICS OF SPECIAL THEORY OF RELATIVITY

Special Theory of Relativity (STR) is a fundamental physical theory that underlies modern physics andhas enormous worldview potential. At the same time, in the process of teaching (studying) the elementsof STR in school and higher education institutions face a number of problems. These problems areprimarily related to the complex mathematical apparatus that describes it; consideration of imaginarymodel representations that do not really exist in nature; formation of the concept of “event” anddistinguishing under different initial conditions of the concepts of “relative”, “portable” and“absolute” movements, etc. In this regard, it is important to find ways to improve the methodology ofstudying the elements of STR, which is what this article is about.The article offers one of the tested options for studying the main provisions of the special theory ofrelativity in the general course of physics, which is taught in the programs of physical andmathematical specialties of pedagogical universities. The main approaches on which the proposedmethodology is based are the reference to the principle of conformity in the transformation of physicaltheories from their partial cases to more general ones. In this regard, the limits of application ofclassical Galilean-Newton mechanics in the plane of absolutization by this theory of categories of spaceand time, the simultaneity of events in a different frame of reference, the instantaneous transmission ofinteractions between bodies at a distance, etc. are analyzed.The physical meaning of Einstein’s postulates, which underlie the theory of relativity, regarding thespecial status of the speed of light propagation as a natural phenomenon is clarified. On the basis ofthese postulates, the formulas of the Lorentz coordinate and time transformations are deduced. Aconsistent, detailed derivation of the formula for the transition coefficient from the Galilean coordinateand time transformations (for the transition from one inertial frame of reference to another) to theLorentz coordinate and time transformations, which reflects their relativistic content, is given. Theestablishment of these formulas is based on the mathematical apparatus, which corresponds to the levelof school mathematical training of participants in the educational process. Based on the obtainedresults on the formulas of Lorentz transformations, the relativity of the concepts of “duration ofevents”, “time intervals”, “changes in size and shape of bodies”, etc. is demonstrated mathematically,if they are considered in reference systems that are in motion relative to each other.
 Keywords: classical mechanics; reference system; the principle of relativity; space-time invariant;coordinate and time conversion.

REVERSE-ENGINEERED DBI-ESSENCE FIELD IN THE RAINBOW GRAVITY

The current astrophysical data sets have implied that our universe has recently entered in an accelerated expansion phase. In literature, it is commonly thought that the late-time speedy enlargement behaviour is caused by mysterious dark contents (dark matter, dark energy and dark radiation) that cannot be observed directly. Although Einstein's General Theory of Relativity has provided very successful theoretical explanations and predictions, it cannot explain the aforementioned unusual nature of the cosmos. This situation has led scientists to try to create a new theoretical model for the nature of dark contents. The cosmological constant, scalar fields, unified energy densities, additional dimension idea and modified gravity theories are among the prominent point of views. In this research, mainly, the reverse-engineering method is taken into account in the rainbow gravity formalism for the DBI-essence scalar field dark energy model. As it is known, scalar field models can be introduced with the help of some fundamental physics theories, but these theories do not provide a direct way to write explicitly the self-interaction potentials that we encounter in scalar field models. Therefore, the reverse-engineering method used in this research takes significant role while writing the self-interaction potential of a scalar field model.

Measurement of the bound-electron g-factor difference in coupled ions

Quantum electrodynamics (QED) is one of the most fundamental theories of physics and has been shown to be in excellent agreement with experimental results1–5. In particular, measurements of the electron’s magnetic moment (or g factor) of highly charged ions in Penning traps provide a stringent probe for QED, which allows testing of the standard model in the strongest electromagnetic fields6. When studying the differences between isotopes, many common QED contributions cancel owing to the identical electron configuration, making it possible to resolve the intricate effects stemming from the nuclear differences. Experimentally, however, this quickly becomes limited, particularly by the precision of the ion masses or the magnetic field stability7. Here we report on a measurement technique that overcomes these limitations by co-trapping two highly charged ions and measuring the difference in their g factors directly. We apply a dual Ramsey-type measurement scheme with the ions locked on a common magnetron orbit8, separated by only a few hundred micrometres, to coherently extract the spin precession frequency difference. We have measured the isotopic shift of the bound-electron g factor of the isotopes 20Ne9+ and 22Ne9+ to 0.56-parts-per-trillion (5.6 × 10−13) precision relative to their g factors, an improvement of about two orders of magnitude compared with state-of-the-art techniques7. This resolves the QED contribution to the nuclear recoil, accurately validates the corresponding theory and offers an alternative approach to set constraints on new physics.

Foundations of Quantum Mechanics

Quantum mechanics is a mathematical formalism that models the dynamics of physical objects. It deals with the elementary constituents of matter (atoms, subatomic and elementary particles) and of radiation. It is very accurate in predicting observable physical phenomena, but has many puzzling properties. The foundations of quantum mechanics are a domain in which physics and philosophy concur in attempting to find a fundamental physical theory that explains the puzzling features of quantum mechanics, while remaining consistent with its mathematical formalism. Several theories have been proposed for different interpretations of quantum mechanics. However, there is no consensus regarding any of these theories.

Entanglement, Complexity, and Causal Asymmetry in Quantum Theories

It is often claimed that one cannot locate a notion of causation in fundamental physical theories. The reason most commonly given is that the dynamics of those theories do not support any distinction between the past and the future, and this vitiates any attempt to locate a notion of causal asymmetry -- and thus of causation -- in fundamental physical theories. I argue that this is incorrect: the ubiquitous generation of entanglement between quantum systems grounds a relevant asymmetry in the dynamical evolution of quantum systems. I show that by exploiting a connection between the amount of entanglement in a quantum state and the algorithmic complexity of that state, one can use recently developed tools for causal inference to identify a causal asymmetry -- and a notion of causation -- in the dynamical evolution of quantum systems. https://doi.org/10.1007/s10701-022-00562-0

Logical and historical review on theoretical physics

Since it started about three centuries ago, theoretical physics went through a huge advancement and, particularly in the last century, the development was material. Its application to engineering brought a massive revolution in the way we humanity live now. Its interpretation opened up astoundingly deep understanding of our universe. One important research activity for the future is to further develop our theories and to further deepen our understanding of the universe. However, as Tomonaga said, when we are in a phase of looking for new paradigm, it is important to understand how our current theory was developed. The purpose of this paper is to present a logical and historic study of the conceptual development of theoretical physics. As the field of theoretical physics is so vast, we cannot cover all theories we have now. We will focus on the most fundamental theories of physics. As this field of physics is as deep and intricate as pure mathematics, if not more, it will be helpful to compare our challenge with that pure mathematicians are facing in the field of the foundations of mathematics. Such common ground will inevitably lead us to deeper philosophical issues. After all what we call physics started with Newton who developed both calculus and dynamics. He called it not physics but natural philosophy. So, it is naturally expected that philosophy, mathematics and theoretical physics develop hand in hand. It has been about a century since these fields started to develop separately and it is about time to restart the original interaction between these three intrinsic intellectual activities. Certainly this will help our timely search for a new paradigm. We must move forward.

Current and Future Tests of General Relativity

General Relativity (GR) holds a special place amongst all fundamental theories of physics: on one hand, it is the theory of all gravitational phenomena; on the other hand, it is also a theory of spacetime [...]

Centering the Everett Interpretation

Abstract I propose an account of probability in the Everett interpretation of quantum mechanics. According to the account, probabilities are objective chances of centered propositions. As I show, the account solves a number of problems concerning the role of probability in the Everett interpretation. It also challenges an implicit assumption, concerning the aim and scope of fundamental physical theories, that is made throughout the philosophy of physics literature.