by jsendak | Sep 25, 2024 | GR & QC Articles
arXiv:2409.15403v1 Announce Type: new
Abstract: In the present Master’s thesis, I describe the research I conducted during my Master’s program on the topic of analogue gravity. This line of research was initiated by Bill Unruh, who established an analogy between hydrodynamic flow with a supersonic region and black holes. One possibility to exploit this hydrodynamics/gravity analogy is to create analogue black holes within Bose-Einstein condensates. At low temperatures, phonons-low energy excitations-behave like a massless scalar field in an emergent acoustic metric determined by the condensate. An acoustic black hole is created by transonic fluid, and quantum fluctuations at the acoustic horizon lead to thermal radiation of phonons, akin to Hawking radiation. This emission has been numerically simulated and experimentally verified in Bose-Einstein condensates. The goal of my Master’s thesis is to design a system in which an acoustic horizon is excited by a gravitational wave-like perturbation. The thesis is divided into two main parts: the first reviews essential topics of general relativity, quantum field theory in curved spacetimes and analogue gravity; while the second presents my results. Firstly, I propose a method to reproduce a gravitational wave perturbation on a flat background acoustic metric emergent from a Bose-Einstein condensate. Secondly, I demonstrate how to implement an impinging gravitational wave-like perturbation at an acoustic horizon. I then analyze how the horizon responds to this analogue gravitational wave and discuss the implications of my work, including potential studies on shear viscosity and entropy density of the perturbed acoustic horizon. Notably, these interesting research directions could be explored in experiments conducted with ultra-cold quantum gas platforms.
Introduction:
This article discusses the research conducted during a Master’s program on the topic of analogue gravity. The author explores the analogy between hydrodynamic flow with a supersonic region and black holes, and proposes the creation of analogue black holes within Bose-Einstein condensates. The thesis is divided into two main parts, with the first reviewing essential topics and the second presenting the author’s results.
Challenges and Opportunities:
Challenges:
- Reproducing a gravitational wave perturbation on a flat background acoustic metric from a Bose-Einstein condensate.
- Implementing an impinging gravitational wave-like perturbation at an acoustic horizon.
Opportunities:
- Studying shear viscosity and entropy density of the perturbed acoustic horizon.
- Exploring interesting research directions in experiments with ultra-cold quantum gas platforms.
Roadmap:
- Introduction: Overview of the research conducted on analogue gravity, hydrodynamic flow, and black holes.
- Review of Essential Topics:
- General relativity.
- Quantum field theory in curved spacetimes.
- Analogue gravity.
- Results:
- Method to reproduce a gravitational wave perturbation on a flat background acoustic metric.
- Implementation of an impinging gravitational wave-like perturbation at an acoustic horizon.
- Analysis of the horizon’s response to the analogue gravitational wave.
- Discussion of implications, including potential studies on shear viscosity and entropy density.
- Conclusion: Summary of the research conducted and the potential for further exploration in experiments with ultra-cold quantum gas platforms.
Conclusion:
The thesis presents research on the creation of analogue black holes within Bose-Einstein condensates by exploiting the analogy between hydrodynamic flow and black holes. The author proposes methods for reproducing gravitational wave perturbations and implementing them at acoustic horizons. The results open up opportunities for studying shear viscosity and entropy density of the perturbed horizon, as well as further experiments with ultra-cold quantum gas platforms.
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by jsendak | Jan 3, 2024 | GR & QC Articles
Utilizing the recently established connection between Palatini-like gravity
and linear Generalized Uncertainty Principle (GUP) models, we have formulated
an approach that facilitates the examination of Bose gases. Our primary focus
is on the ideal Bose-Einstein condensate and liquid helium, chosen as
illustrative examples to underscore the feasibility of tabletop experiments in
assessing gravity models. The non-interacting Bose-Einstein condensate imposes
constraints on linear GUP and Palatini $f(R)$ gravity (Eddington-inspired
Born-Infeld gravity) within the ranges of $-10^{12}lesssimsigmalesssim
3times 10^{24}{text{ s}}/{text{kg m}}$ and
$-10^{-1}lesssimbarbetalesssim 10^{11} text{ m}^2$
($-4times10^{-1}lesssimepsilonlesssim 4times 10^{11} text{ m}^2$),
respectively. In contrast, the properties of liquid helium suggest more
realistic bounds, specifically $-10^{23}lesssimsigmalesssim 10^{23}{text{
s}}/{text{kg m}}$ and $-10^{9}lesssimbarbetalesssim 10^{9} text{ m}^2$.
Additionally, we argue that the newly developed method employing Earth seismic
waves provides improved constraints for quantum and modified gravity by
approximately one order of magnitude.
Conclusions:
The article concludes by stating that the recently established connection between Palatini-like gravity and linear Generalized Uncertainty Principle (GUP) models has allowed for the examination of Bose gases. The ideal Bose-Einstein condensate and liquid helium are used as examples to demonstrate the feasibility of conducting tabletop experiments to assess gravity models.
The non-interacting Bose-Einstein condensate sets constraints on linear GUP and Palatini $f(R)$ gravity, with specific ranges for the parameters $sigma$ and $barbeta$. On the other hand, properties of liquid helium provide more realistic bounds for these parameters.
Furthermore, the article suggests that using Earth seismic waves as a method can greatly improve constraints for quantum and modified gravity by approximately one order of magnitude.
Future Roadmap:
- Further exploration of the connection between Palatini-like gravity and linear GUP models to examine other interesting phenomena and systems.
- Conducting more tabletop experiments to validate and refine the constraints on gravity models using ideal Bose-Einstein condensate and liquid helium.
- Exploring other systems or materials that can provide even more realistic bounds for the parameters $sigma$ and $barbeta$.
- Continued research into the use of Earth seismic waves as a method to improve constraints for quantum and modified gravity.
- Collaboration with experts in the field to gather more data and insights for a comprehensive understanding of gravity models.
Potential Challenges:
- Obtaining accurate and precise measurements in tabletop experiments to validate the constraints on gravity models.
- Identifying suitable systems or materials that can provide more realistic bounds for the parameters $sigma$ and $barbeta$.
- Addressing any limitations or assumptions that may affect the applicability of the connection between Palatini-like gravity and linear GUP models.
- Overcoming technical challenges in utilizing Earth seismic waves as a method to improve constraints for quantum and modified gravity.
Opportunities on the Horizon:
- Potential advancements in technology and measurement techniques that can enhance the accuracy and precision of tabletop experiments.
- Discovery of new systems or materials that can provide even stronger constraints on gravity models.
- Further development of the connection between Palatini-like gravity and linear GUP models, leading to a deeper understanding of quantum and modified gravity.
- Possible collaborations and interdisciplinary research opportunities with experts in different fields to expand knowledge and capabilities in gravity modeling.
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by jsendak | Dec 29, 2023 | GR & QC Articles
The ultraviolet cutoff on a quantum field theory can be interpreted as a
condensate of the affine curvature such that while the maximum of the affine
action gives the power-law corrections, its minimum leads to the emergence of
gravity. This mechanism applies also to fundamental strings as their spinless
unstable ground levels can be represented by the scalar affine curvature such
that open strings (D-branes) decay to closed strings and closed strings to
finite minima with emergent gravity. Affine curvature is less sensitive to
massive string levels than the tachyon, and the field-theoretic and stringy
emergent gravities take the same form. It may be that affine condensation
provides an additional link between the string theory and the known physics at
low energies.
According to the article, the ultraviolet cutoff on a quantum field theory can be interpreted as a condensate of the affine curvature. The maximum of the affine action gives power-law corrections, while its minimum leads to the emergence of gravity. This mechanism can also be applied to fundamental strings, with their spinless unstable ground levels represented by the scalar affine curvature. Open strings (D-branes) decay to closed strings and closed strings eventually reach finite minima with emergent gravity.
The use of affine curvature is advantageous compared to the tachyon as it is less sensitive to massive string levels. Both field-theoretic and stringy emergent gravities exhibit the same form. It is possible that the condensation of affine curvature provides a link between string theory and known physics at low energies.
Future Roadmap
Potential Challenges
- Experimental Verification: The proposed mechanism of affine curvature leading to the emergence of gravity and linking string theory with known physics needs experimental verification. Conducting experiments to validate these concepts may pose significant challenges.
- Theoretical Complexity: Further research and mathematical developments are required to fully understand the implications of affine condensation and its role in linking fundamental strings and quantum field theories.
- Integration with Existing Theories: Integrating this new perspective with existing theories, such as general relativity, may present challenges as it would require reconciling different mathematical frameworks.
Potential Opportunities
- Unified Theory of Gravity: If experimental validation is achieved, the emergence of gravity through affine condensation could potentially lead to the development of a unified theory of gravity, merging quantum field theory and string theory.
- Advancements in Cosmology: Understanding the role of affine curvature in the emergence of gravity may provide new insights into cosmological phenomena, such as the expansion of the universe and the behavior of black holes.
- Technological Applications: Research on affine condensation and its connection to known physics could potentially lead to technological advancements in fields such as quantum computing or high-energy physics.
Conclusion
The concept of affine condensation and its implications for the emergence of gravity provide an intriguing avenue for further exploration. While there are challenges to overcome, such as experimental verification and integration with existing theories, the potential opportunities, including a unified theory of gravity and advancements in cosmology and technology, make this a promising area of research.
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