Physical cosmology

Branch of cosmology which studies mathematical models of the universe

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We include updates on Big Bang, Universe, Expansion of the universe, Dark matter, Observable universe, Multiverse, Cosmic microwave background, Great Attractor, Ultimate fate of the universe, Dark energy, Boltzmann brain, Chronology of the universe, Age of the universe, Redshift, Hubble's law, Anthropic principle ... and more.

2025
Michael Friedman
Passed away while still a Fellow of the American Academy of Arts & Sciences.
March 26 2025
Michael Friedman
Michael Friedman passed away, concluding his distinguished career in philosophy of science and continental philosophy.
March 2025
Phantom energy
The Dark Energy Spectroscopic Instrument (DESI) collaboration published a survey on baryon acoustic oscillations, finding violations of the Lambda-CDM cosmological model within 4 standard deviations. The survey suggested stronger universal acceleration in the early universe, potentially indicating the presence of phantom energy.
2024
Largest cosmic structures
Big Ring was discovered, a cosmic structure made up of galaxy clusters spanning 1.3 billion light-years.
2024
Dwarf galaxy problem
Discoveries indicate that the number of satellite galaxies around the Milky Way might be around 500, challenging previous simulations that predicted fewer galaxies.
2024
Dwarf galaxy problem
Construction of the Vera C. Rubin Observatory is completed, which is expected to conduct wide field surveys to help scientists better understand the dwarf galaxy problem through future sky observations.
2023
Largest cosmic structures
Ho'oleilana Bubble was identified, containing about 56,000 galaxies and located 820 million light-years away, spanning 1 billion light-years.
2023
Cosmological theories
Astrophysicists questioned the Standard Model of Cosmology based on latest James Webb Space Telescope studies, challenging the current understanding of the universe.
June 28 2023
Gravitational wave background
North American Nanohertz Observatory for Gravitational Waves collaboration announced evidence for a Gravitational Wave Background (GWB), with supporting observations from EPTA, Parkes Observatory, and Chinese Pulsar Timing Array (CPTA). This provided the first measurement of the Hellings-Downs curve, a key indicator of gravitational wave origin.
February 2023
Dark energy
Researchers from the University of Hawaiʻi at Mānoa formulated a new theory proposing that black holes gain mass as the universe expands, potentially explaining dark energy through a concept called 'cosmological coupling'.
2022
Largest cosmic structures
King Ghidorah Supercluster was discovered, the most massive galaxy supercluster to date, consisting of at least 15 clusters and interconnected filaments.
2022
Dwarf galaxy problem
Density profile studies suggested that dwarf galaxies have a constant-density core, which contradicts dark matter simulations that predicted lower baryon density.
December 2022
Intracluster medium
The James Webb Space Telescope began studying the faint light emitted in the intracluster medium, advancing our understanding of its properties and composition.
2021
Largest cosmic structures
The 'Giant Arc' was discovered, located 9.2 billion light-years away and spanning 3.3 billion light-years.
2021
Dark energy
A group of researchers argued that observations of the Hubble tension may imply that only quintessence models with a nonzero coupling constant are viable.
2021
Cosmological constant problem
Nikita Blinov and Patrick Draper confirm through the holographic principle that the CKN bound predicts the measured cosmological constant while maintaining effective field theory predictions.
2021
Cosmological theories
James Webb Space Telescope was launched, providing new capabilities for advanced cosmological observations.
July 2021
Universe
LiveScience published an article stating there are approximately 10^82 atoms in the observable universe, providing a quantitative perspective on the universe's scale.
July 2021
Universe
LiveScience reported that there are approximately 1082 atoms in the observable universe, providing a significant insight into the scale of cosmic matter.
2020 A measurement of a unique MOND (Modified Newtonian Dynamics) effect was recorded, offering another alternative explanation to dark matter.
2020
Largest cosmic structures
South Pole Wall was discovered, the largest contiguous feature in the local volume, spanning 1.37 billion light-years and located at the celestial South Pole.
2020
Cosmological theories
Scientists reported verification of measurements from 2011-2014 indicating potential spatial variation in the fine-structure constant, challenging assumptions about the isotropy of the Universe and suggesting possible directionality in natural constants.
2020
Cosmological theories
Physicist Lucas Lombriser proposed a method to reconcile different measurements of the Hubble constant by suggesting a surrounding 'bubble' with different density.
2020
Cosmological theories
Scientists published a study suggesting the Universe might not be expanding uniformly in all directions, challenging the long-accepted isotropy hypothesis by examining galaxy clusters in X-rays.
2019 Observations of Andromeda showed a lack of microlensing effects, suggesting tiny black holes do not exist in significant numbers.
2019
Accelerating expansion of the universe
A research paper analyzed the Joint Light-curve Analysis catalog of Type Ia supernovas, containing ten times more data than the 1998 analyses, questioning the evidence for isotropic acceleration across the universe.
2019
Cosmological theories
The Event Horizon Telescope Collaboration published the first-ever image of a black hole at the center of the M87 Galaxy, verifying Einstein's general theory of relativity.
May 2019 LiteBIRD was selected by the Japanese space agency as the finalist for Japan's second Large-Class Mission, beating OKEANOS in the selection process.
May 2019
Universe
Forbes published an article discussing the impossibility of knowing everything about the universe, highlighting the inherent limitations of human knowledge about cosmic phenomena.
2018
Largest cosmic structures
Hyperion proto-supercluster was discovered, identified as the largest and earliest known proto-supercluster spanning 489 million light-years.
2018
Cosmological constant problem
A mechanism for cancelling the cosmological constant (Λ) is proposed using a symmetry breaking potential in a Lagrangian formalism, where standard matter's pressure counterbalances the cosmological constant's action.
2018
Shape of the universe
Planck mission released final results showing the cosmological curvature parameter, providing evidence consistent with a flat universe.
2018
Dark energy
Oztas et al. developed a model examining the potential evolution of dark energy parameters.
2018
Age of the universe
The Planck Collaboration updated its estimate for the age of the universe, providing a refined measurement of the universe's age.
2018
Reionization
Planck mission results yielded an instantaneous reionization redshift of z = 7.68 ± 0.79, providing a more precise measurement of the cosmic reionization period.
2018
Intracluster medium
A study found the intracluster medium to be an 'accurate luminous tracer of dark matter', providing significant insights into the composition of galaxy clusters.
2018
Cosmological constant problem
Luongo and Muccino propose a mechanism for cancelling the cosmological constant using a symmetry breaking potential, suggesting that standard matter can counterbalance the vacuum energy.
July 2018
Kaluza–Klein theory
A research article challenges the theory of gravity leaking into higher dimensions while supporting the shared dimensional nature of electromagnetism and gravity, lending partial credence to Kaluza-Klein theory.
2016 A test of gravitational lensing in entropic gravity provided a scattered success for alternative hypotheses to dark matter.
2016
Largest cosmic structures
BOSS Great Wall was identified, a structure consisting of 4 superclusters of galaxies with mass and volume exceeding the Sloan Great Wall.
2016
Cosmological theories
LIGO Scientific Collaboration and Virgo Collaboration directly detected gravitational waves, capturing the merger of two black holes and opening a new branch of gravitational-wave astronomy.
February 11 2016
Gravitational wave background
LIGO and Virgo collaborations officially announced the first direct detection and observation of gravitational waves from the September 2015 event.
2015 Gravitational wave measurements detected the merger of intermediate-mass black holes, which increased interest in primordial black holes as a potential dark matter explanation.
2015
Largest cosmic structures
Giant GRB Ring was discovered through gamma-ray burst mapping, identified as the largest-known regular formation in the observable universe at 5.6 billion light-years.
2015
Age of the universe
The Planck Collaboration estimated the age of the universe, producing a slightly higher but statistically consistent estimate compared to the earlier WMAP data, within 68% confidence limits for the base ΛCDM model.
September 2015
Gravitational wave background
First direct detection of gravitational waves from a collision of two black holes, marking a significant milestone in gravitational wave research.
2014
Largest cosmic structures
Hercules–Corona Borealis Great Wall was discovered through gamma-ray burst mapping, spanning 9.7-10 billion light-years.
2014
Cosmological theories
BICEP2 collaboration initially announced detection of inflationary gravitational waves, though confidence was lowered in June of the same year.

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This contents of the box above is based on material from the Wikipedia articles Dwarf galaxy problem, Timeline of cosmological theories, Dark energy, Michael Friedman (philosopher), Cosmological constant problem, Dark matter, Kaluza–Klein theory, Gravitational wave background, Intracluster medium, Universe, Accelerating expansion of the universe, Shape of the universe, Reionization, LiteBIRD, Age of the universe, Phantom energy & List of largest cosmic structures, which are released under the Creative Commons Attribution-ShareAlike 4.0 International License.

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