The electron Born self-energy (eBse) model assumes a finite-sized electron of radius R_e = 1.9 x 10^-20m, determined from electron-positron collisions at LEP. The Born self-energy U_e^B, corresponding to the energy contained in the surrounding electric field, provides a quantitative description of Dark Energy (Astrophys Space Sci 365, 64 (2020); Phys Sci Forum 2, 9 (2021)). Specifically, this model explains (i) the magnitude of DE, (ii) the occurrence of a deceleration-acceleration transition at a redshift z ~ 0.8, and (iii) possesses an equation of state w = -1 (in Quantum Electrodynamics the electron is assumed to be a point particle (R_e = 0); thus, U_e^B ~ 1/R_e is divergent and is “renormalized away” by assuming that U_e^B is contained within the electron rest mass m_e). w = -1 implies that two electron Born masses m_e^B = U_e^B/c² will experience a gravitational repulsion, whereas m_e^B and an uncharged mass will experience the normal gravitational attraction. m_e^B (~ 40 m_p) is a Dark Matter candidate that provides a good description of the Grand Rotation Curves for the Milky Way and M31 galaxies out to distances of ~ 400 kpc (Sci Rep 14, 24090 (2024)) (the difference between DE and DM, in this model, is as follows: DE arises from the time-dependent creation of m_e^B in intergalactic space due to ionization of hydrogen, whereas DM is a time-independent effect arising from the presence of a halo of electrons, along with their associated m_e^B, that surrounds a galaxy). Early in the Universe’s expansion history, for electrons and positrons of finite size, a glass transition occurs at a maximum number density of ~ 1/(2R_e)³ corresponding to physical contact between particles. This glass transition possesses properties akin to Cosmic Inflation (Sci Rep 13, 21798 (2023)). A brief summary of the eBse model and its interconnections to DE, DM, and CI will be provided in this contribution.

The Cosmic Microwave Background (CMB) provides a precise snapshot of the early Universe and encodes detailed information about the fundamental parameters governing cosmological evolution. Conventional approaches to cosmological parameter inference rely on Bayesian sampling techniques combined with numerical Boltzmann solvers, which, while powerful, often obscure the underlying functional relationships between cosmological parameters and observable features of the CMB power spectrum.

In this work, we investigate symbolic regression as an interpretable machine-learning framework for cosmological parameter inference from CMB temperature and polarization power spectra. Using the PySR algorithm, we search for compact, closed-form analytic expressions that relate cosmological parameters to features of the CMB power spectrum, enabling transparent and physically interpretable mappings between theory and observation. Unlike black-box neural networks, symbolic regression yields explicit mathematical expressions that can be directly analyzed and compared with theoretical expectations.

We evaluate the accuracy, complexity, and stability of the recovered symbolic models across multiple cosmological parameters and benchmark their performance against expressions obtained using the AI Feynman algorithm. While AI Feynman performs effectively in low-dimensional settings, we find that its performance degrades as the dimensionality and complexity of the parameter space increase. In contrast, PySR demonstrates greater robustness and flexibility in higher-dimensional regimes relevant to realistic cosmological inference problems.

Our results show that symbolic regression can recover accurate and compact analytic relationships while providing direct physical insight into the structure of the CMB parameter space. This work highlights symbolic machine learning as a promising complementary approach to traditional inference methods and contributes toward more interpretable and physics-informed analyses of cosmological data.

We study the application of Lorentz kinematic transformations deformed by critical velocity to a continuity equation. This generates a source structure for the continuity equation that is indistinguishable from a Nernst–Planck equation. In this case, the fluid flow is the source of excited states. This makes the fluid a type of self-source, where the flow is a force that compensates for its crystallization into excited states. Therefore, we can understand that the kinematic transformation adds a stress term to the fluid dynamics, which can be understood as a sort of dark energy.

We studied the effects of the currents that arise. Specifically, the dissipative and convective currents, which play a role of self-induction and mutual induction, are capable of generating local phase transitions in the fluid.

This construction is a step toward building a theory of gravity based on a theory of two self-interacting fluids. In future work, we will clarify the role of vorticity, include viscosity effects, and relate this to Helmholtz–Hodge decomposition. We will also clarify the dynamic role of critical velocity as a fundamental state and its effect on the causal structure of the fluid, in addition to investigating a possible condition of non-integrability, which should severely affect the construction of the causal structure.

Using arguments based on fundamental principles, Freeman Dyson concluded that the individual measurement of the graviton is physically impossible. Considerable research has been dedicated to find the graviton through single-point detections, all of which supports Dyson's conclusion. The community of gravitational physicists still search for the graviton through means of single-point detections; however, there is a much greater possibility of successfully finding the graviton through bipartite detections. Our research follows up on the paper "Measurement-induced entanglement entropy of gravitational wave" by Preston Jones, Quentin G. Bailey, Andri Gretarsson, and Edward Poon in Physics Letters B and explores other possible methods of finding signatures of non-classicality in gravitational waves. The calculations performed to produce their Figure 2 are updated from Mathcad to Python to be more readily available for use in other measures of non-classicality. Bipartite detections allow for the observation of the measurement-induced entanglement entropy, which is a signature of non-classicality in gravitational waves. Bunching is another potential signature of non-classicality that can easily be observed in bosons with bipartite detections through Hanbury-Brown and Twiss experiments but is complicated by the optical equivalence theorem. However, bipartite detections also present the opportunity to observe anti-bunching, a purely quantum mechanical effect, which would prove that gravity is quantized. Bipartite detections are very likely the key to find the smoking gun for the quantization of gravity.

Current research into the quantization of gravity has focused primarily on single-point graviton detections. This approach neglects non-classical properties that arise from entanglement between gravitons whose arrivals are coincident at separate detector sites. In developing a bipartite quantum-mechanical framework for the detection of gravitational waves, a necessary step is to characterize detector efficiency for graviton particles. Utilizing the geodesic deviation equation, we construct a model of the detector's departure from free fall in flat spacetime. This model enables us to compute the mean graviton number registered by a single detector, providing a semi-classical measure of effective detector efficiency. We find that low detector efficiency results in resolvable measurement-induced entanglement in bipartite gravitational-wave detections. This work follows up on ``Measurement-induced entanglement entropy of gravitational wave detections'' (Physics Letters B, 2025) by Preston Jones, Quentin G. Bailey, Andri Gretarsson and Edward Poon, which states that low theoretical efficiencies present a challenge for detecting production-induced entanglement. In contrast, for bipartite detections of gravitational waves involving measurement-induced entanglement, the entanglement occurs at the time of measurement. Low detector efficiencies therefore become an asset for revealing non-classical signatures, since quantum effects are more prominent as a result of the reduced graviton number associated with low detector efficiency.

We investigate the generation and harvesting of entanglement between two identical, comoving Unruh–DeWitt detectors in cosmological de Sitter spacetime. Initially, the detectors are unentangled and interact locally with a complex scalar field, through which an effective coupling between them emerges. Our analysis considers two types of complex scalar fields, the conformally invariant field and the massless minimally coupled field, both of which exhibit distinct physical behaviours in curved spacetime. By tracing out the scalar-field degrees of freedom, we construct the reduced density matrix of the detector pair. The eigenvalues of this matrix encode the transition probabilities between the energy levels of the detectors and allow us to compute the negativity, which serves as a quantitative measure of the entanglement generated at late times.

We present a detailed comparison of the entanglement-harvesting capabilities of the two complex fields, highlighting both their similarities and their qualitative differences. To place our findings in context, we also contrast them with the well-studied case of a real scalar field. Our results show that complex fields and nonlinear couplings significantly enhance the robustness of entanglement harvesting, allowing entanglement to persist over a broader parameter range. This indicates that the structure of the underlying field theory plays a crucial role in determining the efficiency of entanglement generation in curved spacetime.

In this work, we investigate the localization properties of Elko spinor fields on the Bloch brane, a thick brane scenario generated by two interacting scalar fields and characterized by a rich internal structure. We begin by studying the dynamics of a free (massless) Elko field in the five-dimensional Bloch brane background and derive the corresponding Schrödinger-like equation governing the Kaluza–Klein modes. Our analysis shows that, due to the specific geometric features and the non-trivial warp factor of the Bloch brane, the zero mode of a free Elko field is not normalizable and therefore cannot be localized on the brane.

To resolve this issue, we introduce a non-minimal coupling term into the five-dimensional Elko spinor field action. By considering different forms of coupling between the Elko field and the background scalar fields, we demonstrate that the inclusion of such a coupling significantly alters the effective potential of the system and allows for the localization of the Elko zero mode. We identify the explicit conditions under which a normalizable and physically acceptable zero mode can be trapped on the brane.

Furthermore, we examine how the internal structure of the Bloch brane influences the localization mechanism. Our results reveal that the brane’s internal layers play a crucial role in shaping the effective potential felt by the Elko field, thus affecting both the localization behavior and the profile of the zero mode. This study provides deeper insight into the realization of dark-matter-motivated Elko fields in thick brane models.

Background: The Event Horizon Telescope (EHT) provides unprecedented horizon-scale images of supermassive black holes, offering a unique testing ground for theories of gravity. The Nexus Paradigm (NP), a quantum gravity model, posits a quantized spacetime with a halved Schwarzschild radius and makes distinct predictions for observable features like the dark depression and emission ring.

Methods: We perform a rigorous Bayesian statistical analysis to test the NP against EHT observations of Sgr A* and M87*. Using Gaussian likelihoods and priors informed by mass–distance uncertainties, we compute the posterior distribution for the angular scale parameter Θ_g and assess the model's goodness of fit via the χ² statistic. We directly compare the NP to General Relativity (GR) using Bayes factors.

Results: The NP demonstrates remarkable agreement with the data, achieving a combined fit at a 4.37σ confidence level (99.997%). Predictions for the dark depression, emission ring, and base diameter all agree with observations at the <0.1σ level. In stark contrast, GR's prediction for the dark depression is inconsistent at the ~13σ level. The Bayes factor overwhelmingly favors the NP over GR, at approximately 10³⁶.

Conclusion: Our analysis provides strong statistical validation for the Nexus Paradigm as a viable quantum gravity framework. These results underscore the power of EHT observations to probe the quantum nature of spacetime and challenge classical gravitational models in the strong-field regime.

This talk lies at the interface between field theory and foundations of quantum mechanics. I will be speaking about a quintessential quantum mechanical phenomenon, entanglement, mostly in the context of quantum field theory in 1+1D. In this setting, I will introduce some of the most studied bipartite entanglement measures that are investigated in the context of many-body quantum physics: entanglement entropy, Rényi entropies, logarithmic negativity and symmetry-resolved measures. I will explain what the study of entanglement measures signifies within quantum field theory, especially how such measures are effective probes for a wide range of universal properties from identifying critical points and gapped phases to classifying quantum states according to area or volume laws, quantifying the speed of thermalization after a quantum quench, or identifying symmetries and their breaking. I will illustrate some of these points with results from my own work of the past 20 years, particularly the branch point twist field technique that I co-pioneered with J. L. Cardy and B. Doyon in our paper https://arxiv.org/abs/0706.3384. This method relates all measures of entanglement mentioned above to correlation functions of local fields and has enabled us to apply known techniques to compute correlators to the investigation of entanglement measures. Also see the recent review https://arxiv.org/abs/2403.06652.

Black holes, as characterized by the Hawking effect and Bekenstein-Hawking entropy, can be treated as a compact object carrying nontrivial quantum information obscured behind the event horizon. Thus, the black hole may convey and retract its quantum information to the nearby quantum probes via the surrounding mediator fields. In this paper, we investigate the effects of a quantum black hole on the reduced states of a pair of static qubit-type Unruh-DeWitt (UDW) detectors acting as a probe, using three complementary quantum information measures: concurrence characterizing entanglement harvesting, quantum discord, and Bell's nonlocality bound. This sheds light on the nature of the quantum state of the black holes. By treating the black hole as a tidally deformable thermal body under the quantum fluctuation of the mediator fields as observed in \cite{Goldberger:2019sya, goldberger2020virtual, biggs2024comparing}, we employ a post-Newtonian effective field theory (PN-EFT) to derive the reduced states of the UDW probes analytically. Based on this, we can easily obtain all three quantum information measures without encountering the complicated Matsubara sum of infinite thermal poles, as in the conventional approach based on quantum fields in curved spacetime. By tuning the relative strengths in the action of PN-EFT, we can extract the effects of the black hole on the entanglement, quantum correlation, and nonlocality bound of the UDW probe systems. Our PN-EFT approach can be extended to include the backreaction on the black holes in future studies by taking the higher-order PN corrections into account.