Tag

Universe Expansion

All articles tagged with #universe expansion

science4 days ago•18 min saved

Sizing the Cosmos: How the Observable Universe Expands Through Time

By applying the Friedmann equations—relating the expansion rate to the Universe's energy content (radiation, matter, dark energy) and curvature—cosmologists compute the observable Universe's size at any epoch. With current measurements of the Hubble constant and energy fractions, the present horizon is about 46 billion light-years across, and its past growth traces radiation-dominated, then matter-dominated, and now dark-energy–dominated expansion, yielding precise milestones for when the Universe reached fractions of its current size.

via Big Think|

#cosmology #dark-energy #friedmann-equations

space1 month ago•2 min saved

Cosmic Acceleration Without Dark Energy? New GR-Based Model Claims Yes

A new paper argues that the universe’s accelerating expansion can be explained purely within Einstein’s general relativity by treating Friedmann spacetimes as unstable during the early radiation era, producing accelerations that mimic dark energy without needing a cosmological constant or exotic energy. If borne out, this approach could replace or modify the standard lambda-CDM model, though its adoption remains uncertain.

via Gizmodo|

#cosmology #dark-energy #friedmann-spacetime

space2 months ago•64 min saved

Universe Could End in 33 Billion Years, New Dark-Energy Model Suggests

A new study applying a hybrid axion dark energy model to Dark Energy Survey data hints that dark energy may be dynamic. If correct, this could cause the universe’s expansion to slow, halt, and reverse, leading to a Big Crunch about 33.3 billion years from now—much sooner than the trillion-year lifetime traditionally assumed—though the result depends on several variables and requires further verification.

via Live Science|

#axion #big-crunch #cosmology

space2 months ago•5 min saved

Largest 3D Map of the Universe Deepens Cosmology Puzzle

DESI finished its first official survey, delivering the largest high‑resolution 3D map of the cosmos—47 million galaxies and 20 million stars across 11 billion years—unlocking a data trove that could test the constant nature of dark energy (lambda) and reveal potential evolution. While previous hints suggested possible tensions with the standard model, scientists emphasize careful error analysis and independent confirmation. With six data‑heavy paper batches planned and follow‑on surveys like Euclid and Rubin Observatory on the horizon, the DESI results are likely to refine or challenge current cosmology rather than settle it outright.

via Gizmodo|

#cosmology #dark-energy #desi

science2 months ago•3 min saved

New Hubble Constant Precision Keeps Cosmology in Tension

An international team reports the most precise measurement of the Hubble constant to date (about 73.5 km/s/Mpc with ~1% accuracy). While tighter, the result reinforces the long-standing Hubble tension between local measurements and the standard cosmological model, raising the possibility of undiscovered physics or systematic issues and underscoring the need to reassess our understanding of the universe’s expansion.

via Futurism|

#astrophysics #cosmology #hubble-constant

science3 months ago•4 min saved

Cosmic Expansion Seems Faster Than Thought, Sparking Cosmology Questions

A global team using the cosmic distance ladder reports the universe is expanding at about 73.5 km/s per Mpc, faster than the previous ~67, a discrepancy that challenges current cosmology and could reveal gaps in our understanding of dark energy, gravity, or distance measurements.

via VICE|

#astronomy #astrophysics #cosmology

science6 months ago•15 min saved

Understanding 'Gravitationally Bound' in an Expanding Universe

The article explains what it means for objects to be gravitationally bound in an expanding universe, discussing how structures like stars, galaxies, and clusters are held together by gravity despite the universe's overall expansion, and explores how dark energy influences the future of these structures.

via Big Think|

#cosmic-structures #dark-energy #galaxy-clusters

science6 months ago•3 min saved

James Webb Space Telescope: A New Era in Cosmic Observation

Launched on December 25, 2021, the James Webb Space Telescope has significantly advanced our understanding of the universe by capturing detailed images of the early cosmos, confirming existing theories, and raising new questions about cosmic evolution, exoplanets, and black holes, despite initial delays and budget overruns.

via Live Science|

#cosmic-dawn #exoplanets #infrared-imaging

science7 months ago•4 min saved

NASA's Roman Telescope to Explore Cosmic Voids and Map the Milky Way

NASA's Nancy Grace Roman Space Telescope will map thousands of cosmic voids to better understand the universe's expansion and the nature of dark energy by observing the distribution and shapes of these vast, sparsely populated regions, which can reveal key insights into the universe's composition and evolution.

via NASA (.gov)|

#cosmic-voids #dark-energy #nasa

science8 months ago•26 min saved

Universe's Expansion Is Now Slowing Down

A recent study suggests that the universe's expansion is slowing down rather than accelerating, challenging the standard cosmological model and implying potential new physics or models like a cyclic universe. The findings focus on the impact of progenitor star age on Type Ia supernova luminosity, which could bias previous measurements of cosmic expansion. While intriguing, the results are met with cautious skepticism and require further validation with upcoming data.

via Hacker News|

#big-bounce #cosmology #dark-energy

science8 months ago•4 min saved

Emerging Evidence Indicates Universe's Expansion Is Slowing, Challenging Dark Energy Theories

New research suggests that the universe's expansion may be slowing down and dark energy might not be accelerating it anymore, potentially marking a major shift in cosmological understanding. This conclusion is based on findings that challenge the standard model of dark energy, indicating the universe has already entered a phase of decelerated expansion, with future observations from the Vera C. Rubin Observatory expected to further test these results.

via Space|

#cosmology #dark-energy #desi

science8 months ago•5 min saved

Emerging Evidence Indicates Universe's Expansion Is Decelerating

A new study suggests that the universe's expansion is slowing down rather than accelerating, challenging the long-held belief that dark energy is causing an ever-increasing expansion rate. The findings indicate that dark energy may weaken over time, leading to a transition from acceleration to deceleration, which could significantly alter our understanding of the universe's past and future.

via Phys.org|

#bao #cosmology #dark-energy

science8 months ago•6 min saved

Potential Clues to the Pre-Big Bang Universe

Recent cosmological research suggests that understanding the universe's ultimate fate—whether it will end in a Big Crunch, Big Freeze, or a cyclical Big Bounce—could provide insights into what preceded the Big Bang, especially with new evidence indicating that dark energy may not be constant but evolving over time, possibly involving particles called axions that influence cosmic expansion.

via BBC Science Focus Magazine|

#big-bang #cosmology #cyclical-universe

science8 months ago•18 min saved

Scientists Warn Universe May End in a Big Crunch Within 20 Billion Years

Recent observations suggest dark energy may be weakening, which could imply a potential, though currently unlikely, future scenario of a Big Crunch, but the evidence is not yet conclusive and further data is needed to determine the universe's ultimate fate.

via Big Think|

#big-crunch #cosmology #dark-energy

science8 months ago•5 min saved

New Theory Explores Why the Universe's Expansion Accelerates

A new study proposes that the universe's accelerating expansion can be explained by a modified geometry of spacetime, called Finsler geometry, without invoking dark energy, by allowing measurements to depend on direction and velocity, which could reshape our understanding of cosmic dynamics.

via Earth.com|

#cosmic-acceleration #cosmology #dark-energy-alternative