Tag

String Theory

All articles tagged with #string theory

physics2 months ago•8 min saved

Bootstrapping String Theory: From Minimal Constraints to a Unique High-Energy Description

A bootstrap analysis shows that, under ultrasoft high-energy behavior and the assumption that Regge zeros are the only zeros, the 4- and 5-point scattering amplitudes for identical scalars are uniquely fixed to the string-theory form, implying string dynamics may emerge from fundamental consistency principles rather than being assumed a priori. Built on Lorentz invariance, crossing symmetry, positivity, and analyticity, the result supports string universality but depends on whether these inputs can be independently justified or if other assumptions yield the same outcome.

via American Physical Society|

#bootstrap #high-energy-physics #physics

science2 months ago•11 min saved

Hidden Dimension May Unify Dark Energy and Dark Matter

New observations hint that dark energy may not be constant and could interact with dark matter. Building on DESI results that dark energy evolves over time, theorists are testing models where the energy density of dark energy and the mass of dark matter change in tandem, potentially via a dark, micron-scale dimension suggested by string theory. In this picture, gravitons could leak into the dark dimension, producing dark gravitons that drive the coupling between the two dark components and possibly helping to resolve the Hubble tension. While intriguing and partially compatible with data, these ideas remain theoretical and require further observational tests.

via Quanta Magazine|

#cosmology #dark-dimension #dark-energy

science3 months ago•8 min saved

Bootstrap Findings Hint at String Theory from First Principles

Caltech and NYU researchers show that two basic high-energy scattering assumptions—ultrasoftness that tames infinities and minimal zeros—lead to the defining features of string theory, including its infinite tower of particles, without assuming strings from the start. While not experimental proof, the work demonstrates that string-like behavior can emerge from simple principles, reviving the bootstrap approach to quantum gravity.

via Caltech|

#bootstrap #quantum-gravity #scattering-amplitudes

science4 months ago•100 min saved

Nobel Physicist warns humanity may not live to see a Theory of Everything

Live Science entrevistates Nobel laureate David Gross about the quest to unite gravity with the other fundamental forces, the challenges of testing a Theory of Everything, and his sobering view that humanity may not survive long enough to witness it due to the ongoing nuclear-arms risk and the accelerating potential of AI-enabled weapons, calling for renewed diplomacy to reduce existential threats.

via Live Science|

#asymptotic-freedom #existential-risk #nuclear-weapons

science4 months ago•13 min saved

What 'Real' Means for the Multiverse, According to an Astrophysicist

The piece argues that the 'reality' of a multiverse hinges on definition: while quantum mechanics’ many-worlds view and string theory’s landscape offer frameworks in which multiple universes could exist, there is no direct evidence for other universes. Indirect hints might come from how these theories predict physics at tiny scales or high-energy experiments, but proving a multiverse remains elusive.

via The Conversation|

#cosmology #multiverse #quantum-mechanics

science5 months ago•14 min saved

Bootstrapping String Theory: New Results Refresh the Debate

The article surveys string theory’s status: critics call it untestable amid a vast landscape of possible configurations, but recent bootstrapping work shows the Veneziano amplitude can emerge as a unique outcome under certain high-energy assumptions, reviving the question of whether string theory is the sole correct description of quantum gravity. While mathematically intriguing, these results are debated and lack experimental confirmation, leaving the theory’s ultimate status unresolved.

via Quanta Magazine|

#bootstrapping #quantum-gravity #science

science7 months ago•9 min saved

String Theory Constructs a Concrete de Sitter Universe with Dark Energy

Bruno Bento and Miguel Montero propose an explicit de Sitter solution in string theory by compactifying extra dimensions on a six-dimensional flat manifold and balancing a Casimir-like effect with flux, producing a small positive dark energy around 10^-15 in Planck units. While a significant step toward matching string theory to our universe and building on Eva Silverstein's ideas, the solution remains five-dimensional and dynamically unstable: the dark energy is expected to weaken over a Hubble time, and researchers still aim to obtain a fully four-dimensional model.

via Quanta Magazine|

#casimir-effect #compactification #dark-energy

science1 year ago•13 min saved

Unveiling Scalar Fields: The Hidden Force in Physics

Scalar fields, fundamental in theoretical physics, represent the simplest type of field, providing a single value at each point in space and time, such as height above sea level. In contrast, vector fields include direction, essential for describing forces and motion. More complex phenomena, like spacetime curvature in Einstein's theory of relativity, require tensor fields. Scalar fields are crucial in both classical and quantum physics, but string theory's challenge lies in reconciling its extra scalar components with the observed tensor nature of spacetime.

via Big Think|

#einstein #scalar-fields #science

science1 year ago•2 min saved

Physicists Edge Closer to Cracking Time Travel Code

Physicists are exploring the theoretical concept of cosmic strings, which are incredibly dense and slender structures that could potentially unlock the secrets of time travel. These strings, possibly originating from string theory or as relics from the early Universe, might create loops in space-time, acting as wormholes. Detecting cosmic strings is challenging due to their elusive nature, but they could be identified through gravitational lensing effects or microlensing in stars, offering a potential pathway to paradox-free time travel.

via BGR|

#astrophysics #cosmic-strings #gravitational-waves

science2 years ago•11 min saved

Unveiling the Dark Mirror Universe: A New Theory on Dark Matter

Scientists have proposed the dark dimension scenario, which suggests that dark matter could be explained by an as-yet-unseen dimension within the framework of string theory. This scenario offers a specific recipe for dark matter and proposes an intimate connection between dark matter and dark energy. While there is no evidence yet for the dark dimension, the scenario makes testable predictions for both cosmological observations and tabletop physics, providing opportunities for empirical scrutiny. If supported by upcoming tests, the dark dimension hypothesis has the potential to bring us closer to understanding dark matter, dark energy, and the weakness of gravity compared to other forces.

via WIRED|

#cosmology #dark-matter #experimental-physics

physics2 years ago•9 min saved

"Physicists' Quest: Uncovering Missing Matter in the Dark Dimension"

Physicists are exploring the concept of a "dark dimension" within the framework of string theory to explain the minuscule value of the cosmological constant and the potential emergence of lightweight, weakly interacting particles. This theory posits the existence of dark gravitons, which could serve as candidates for dark matter and have implications for the distribution of galaxies. While the idea is intriguing, some physicists remain skeptical, but upcoming experiments, including cosmological surveys and laboratory tests, may provide evidence to support or refute the dark dimension hypothesis and shed light on the nature of dark matter and the forces of gravity.

via Quanta Magazine|

#cosmological-constant #dark-matter #extra-dimensions

science2 years ago•6 min saved

"The Mathematical Genius Behind String Theory"

Eugenio Calabi, a renowned mathematician, made groundbreaking contributions to geometry, particularly in his 1953 conjecture about a special class of manifolds known as Kähler manifolds. His work on these manifolds, now called Calabi-Yau manifolds, became crucial in both mathematics and physics, particularly in the development of string theory. Calabi's conjecture, initially doubted by others, was eventually proven by mathematician Shing-Tung Yau, leading to the mathematical existence of Calabi-Yau manifolds. These manifolds, with their hidden dimensions, became a key component in string theory, offering a potential explanation for the fundamental particles and forces of nature. Calabi's passion for mathematics persisted throughout his life, and he continued to conduct research well into his 90s.

via Quanta Magazine|

#calabi-yau-manifolds #eugenio-calabi #geometry

astronomy2 years ago•4 min saved

"Unveiling the Intriguing Argument for a Compact Cosmos"

A new study challenges the prevailing belief that the universe is much larger than what we can observe. While most cosmologists think the observable universe is just a small part of an unimaginably vast creation, this study argues that the observable universe is mostly all there is. The authors propose a higher-dimensional structure within string theory that matches observations and avoids the theoretical "swampland." If confirmed, this would mean the universe is only a hundred or a thousand times larger than what we can observe, significantly smaller than the early inflation models.

via Phys.org|

#astronomy #cosmic-inflation #cosmology

astronomy3 years ago•3 min saved

"Unveiling the Power of a Compact Cosmos"

A new study challenges the prevailing belief that the Universe is much larger than what we can observe. Most cosmologists think the observable universe is just a small part of an unimaginably vast or infinite creation. However, this study proposes that the observable universe is mostly all there is. By considering higher-dimensional structures within string theory, the authors suggest that the Universe may only be a hundred or a thousand times larger than what we can observe. While speculative, this alternative model avoids the theoretical "swampland" and questions the need for early cosmic inflation. Further research and observations are needed to confirm or refute these ideas.

via Universe Today|

#astronomy #cosmic-inflation #cosmology

science3 years ago•5 min saved

Dark Matter Linked to Universe's Clumpiness in New Discovery

Researchers at the University of Toronto propose that the universe's lack of clumpiness suggests dark matter is composed of hypothetical, ultra-light particles called axions. This could have broad implications for our understanding of the universe and could even provide support for string theory. The "clumpiness problem" may be a sign that dark matter is composed of axions. The implications of proving the existence of hard-to-detect axions extend beyond understanding dark matter and could address fundamental questions about the nature of the universe itself.

via SciTechDaily|

#axions #cosmic-web #dark-matter