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#cosmology

20 posts9 participants0 posts today
Public
Daniel Pomarède

From the Princeton University Department of Astrophysical Sciences:

Jeremiah P. Ostriker, Emeritus Professor of Astrophysical Sciences Passes Away at the age of 87

web.astro.princeton.edu/news/j

Jerry Ostriker
Department of Astrophysical SciencesJeremiah P. Ostriker, Emeritus Professor of Astrophysical Sciences Passes Away at the age of 87Jeremiah P. Ostriker, Charles A. Young Professor of Astronomy on the Class of 1897 Foundation, Emeritus passed away on the morning of April 6th at his home in New York City.  Ostriker was one of the most pre-eminent theoretical astrophysicists in the last half-century, making fundamental contributions to our understanding of the interstellar medium
#Cosmology
Public
Daniel Pomarède

Hercules-Corona Borealis Great Wall: an update

Turns out the largest known structure in the observable universe is larger than previously thought, with members potentially spanning the redshift range of 0.33 < z < 2.43

by Istvan Horvath and co-authors
arxiv.org/abs/2504.05354

arXiv logo
arXiv.orgScanning the Universe for Large-Scale Structures using Gamma-Ray BurstsIn the past few decades, large universal structures have been found that challenge the homogeneity and isotropy expected in standard cosmological models. The largest of these, identified as the Hercules-Corona Borealis Great Wall, was found in 2014 in the northern galactic hemisphere in the redshift range of 1.6 < z < 2.1. Subsequent studies used an increasing gamma-ray burst database to show that the cluster was unlikely to have been caused by statistical sampling uncertainties. This study re-examines burst clustering in the northern galactic hemisphere using a recently developed methodology. Evidence is provided that the Hercules-Corona Borealis Great Wall cluster is larger than previously thought, with members potentially spanning the redshift range of 0.33 < z < 2.43. The extension of this cluster's size does not appear to have been due to statistical variations or sampling biases.
#Cosmology
Public
Daniel Pomarède

Jeremiah Ostriker, Who Plumbed Dark Forces That Shape Universe, Dies at 87

There’s more to the universe than meets the eye, he found. His studies led astronomy to the dark side, changing our view of what’s out there.

✍️ by Dennis Overbye
nytimes.com/2025/04/07/science

Jeremiah Ostriker in an undated photo. His work altered humankind’s understanding of how galaxies are formed and evolve, and what the universe is made of.
The New York Times · Jeremiah Ostriker, Who Plumbed Dark Forces That Shape Universe, Dies at 86By Dennis Overbye
#Cosmology
Public
Daniel Pomarède

#Cosmology

416 pages, 538 authors, 4256 references

The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics

by Eleonora Di Valentino and co-authors
arxiv.org/abs/2504.01669

arXiv logo
arXiv.orgThe CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physicsThe standard model of cosmology has provided a good phenomenological description of a wide range of observations both at astrophysical and cosmological scales for several decades. This concordance model is constructed by a universal cosmological constant and supported by a matter sector described by the standard model of particle physics and a cold dark matter contribution, as well as very early-time inflationary physics, and underpinned by gravitation through general relativity. There have always been open questions about the soundness of the foundations of the standard model. However, recent years have shown that there may also be questions from the observational sector with the emergence of differences between certain cosmological probes. In this White Paper, we identify the key objectives that need to be addressed over the coming decade together with the core science projects that aim to meet these challenges. These discordances primarily rest on the divergence in the measurement of core cosmological parameters with varying levels of statistical confidence. These possible statistical tensions may be partially accounted for by systematics in various measurements or cosmological probes but there is also a growing indication of potential new physics beyond the standard model. After reviewing the principal probes used in the measurement of cosmological parameters, as well as potential systematics, we discuss the most promising array of potential new physics that may be observable in upcoming surveys. We also discuss the growing set of novel data analysis approaches that go beyond traditional methods to test physical models. [Abridged]
Public
Till Sawala

You can't make this up. The #tarrifs that will impact trillions in international trade are literally based on a "back of the envelope" calculation, so primitive and flawed it would get you thrown out of a #cosmology seminar - and believe me, that's really saying something!

Absolutely mind-blowing 🤯

Public
Daniel Pomarède

in the #arXiv

The Eras Tour: Mapping the Eras of Taylor Swift to the Cosmological Eras of the Universe

Submitted to Acta Prima Aprilia by Jane C. Bright
arxiv.org/abs/2503.22795

arXiv logo
arXiv.orgThe Eras Tour: Mapping the Eras of Taylor Swift to the Cosmological Eras of the UniverseThis paper explores an unexpected yet compelling parallel between the evolution of the universe, as described by cosmological eras, and the artistic evolution of Taylor Swift, delineated by her distinct album eras. By mapping key characteristics and transitions in the universe's history to corresponding themes and milestones in Swift's career, I offer a novel perspective on both. I culminate with predictions for Swift's future work and dare to ask a question of cosmic importance: Could Taylor Swift's thirteenth album hold the secret to the universe's ultimate destiny?
#Cosmology#TaylorSwift#aprilfools
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Suzanne Aldrich (she/her)

🎬 PS: For a beautifully clear (and delightfully mind-bending!) explanation of what might have existed before the Big Bang, check out PBS Space Time’s fantastic episode, "What Happened Before the Big Bang?" hosted by astrophysicist Matt O’Dowd. Highly recommended as a thoughtful companion to this thread! 🌌🌀✨

👉 Watch it here on PBS Space Time pbs.org/video/what-happened-be

www.pbs.orgPBS Space Time | What Happened Before the Big Bang? | Season 5 | Episode 29We actually have a pretty good idea of what might have happened before the Big Bang.
#PBS#SpaceTime#Cosmology
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Suzanne Aldrich (she/her)

📝 Important note:
These visuals are illustrative only—not precise physical depictions of magnitudes or forces involved. Actual conditions during inflation involved extreme energies (near ~10¹⁶ GeV), densities, and scales far beyond intuitive visualization. My illustrations aim purely for conceptual clarity.

Enjoy exploring our cosmic origins! ✨🔭🌠
#Cosmology #Inflation #BigBang #PrimordialBlackHoles #QuantumPhysics #Astrophysics

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Suzanne Aldrich (she/her)

🕳️ Clip 8: Transition to Primordial Universe (Black Holes Form)
This visualization illustrates tiny density fluctuations collapsing into primordial black holes (PBHs) within the hot early universe plasma—originally proposed by Hawking & Carr (1970s). PBHs could influence cosmic structure and potentially explain dark matter. Observational searches ongoing, including data from JWST, LIGO, and future space missions.
🎬 Watch the full-res Sora videos here! sora.com/g/gen_01jqmfmsabfbfsr
🔗 Primordial Black Holes (Carr, Hawking) arxiv.org/abs/2002.12778
🔭 Evidence: Ongoing searches via gravitational lensing (JWST), gravitational waves (LIGO), and large-scale surveys (DESI).
#Cosmology #Inflation #BigBang #PrimordialBlackHoles #QuantumPhysics #Astrophysics

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Suzanne Aldrich (she/her)

🔥 Clip 7: Reheating Begins
Depicted here is "reheating," where the inflaton’s potential energy rapidly converts into hot plasma of standard model particles, marking the Big Bang's fiery start (~10²⁷ Kelvin initially). This transition phase, predicted by cosmologists including Linde, remains theoretically robust yet poorly understood.
🎬 Watch the full-res Sora videos here! sora.com/g/gen_01jqmfg100eb7r3
🔗 Reheating theory overview arxiv.org/abs/1001.2600
🛰️ Evidence: Consistent with nucleosynthesis abundances and CMB measurements from Planck.
#Cosmology #Inflation #BigBang #PrimordialBlackHoles #QuantumPhysics #Astrophysics

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Suzanne Aldrich (she/her)

🎢 Clip 6: Slow-Roll Transition
This clip illustrates "slow-roll" inflation, introduced by Andrei Linde. After bubble nucleation, the inflaton field rolls slowly toward a true vacuum. Inflation gradually ends as the energy density decreases. "Slow-roll" inflation precisely matches observational constraints from CMB temperature anisotropies.
🎬 Watch the full-res Sora videos here! sora.com/g/gen_01jqn1yrwcf8b9k
🔗 Slow-roll inflation (Linde) arxiv.org/abs/hep-th/9405187
🔭 Evidence: Precise fits to Planck and WMAP observations of the CMB spectrum.
#Cosmology #Inflation #BigBang #PrimordialBlackHoles #QuantumPhysics #Astrophysics

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Suzanne Aldrich (she/her)

🌀 Clip 5: Bubble Expansion
Visualizing the true vacuum bubble rapidly expanding into the false vacuum. This phase boundary would propagate at enormous speeds, eventually dominating space. This idea relates to Guth's "bubble universe" scenario and the multiverse hypothesis (eternal inflation) proposed by Paul Steinhardt and Alexander Vilenkin.
🎬 Watch the full-res Sora videos here! sora.com/g/gen_01jqmf0h6begta7
🔗 Eternal Inflation (Steinhardt, Vilenkin) scientificamerican.com/article
🛰️ Evidence: Indirect—no direct detection yet; remains theoretical.
#Cosmology #Inflation #BigBang #PrimordialBlackHoles #QuantumPhysics #Astrophysics

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Suzanne Aldrich (she/her)

💥 Clip 4: Tunneling Begins (Bubble Nucleation)
This clip represents the theoretical nucleation of a true vacuum bubble, transitioning from a high-energy false vacuum—a scenario described by Sidney Coleman & Frank De Luccia in the 1980s. Quantum tunneling initiates bubble formation.
🎬 Watch the full-res Sora videos here! sora.com/g/gen_01jqmdvxawe8pv2
🔗 Coleman-De Luccia tunneling journals.aps.org/prd/abstract/
🔭 Evidence: Indirectly consistent with structure formation data; currently theoretical and not directly observable. #Cosmology #Inflation #BigBang #PrimordialBlackHoles #QuantumPhysics #Astrophysics

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Suzanne Aldrich (she/her)

🌌 Clip 3: Quantum Fluctuations Appear
Tiny quantum fluctuations in the inflaton field are illustrated here. Inflation stretched these quantum ripples to enormous scales, seeding all cosmic structures (galaxies, stars). Theoretical predictions by Viatcheslav Mukhanov and Stephen Hawking matched detailed observations.
🎬 Watch the full-res Sora videos here! sora.com/g/gen_01jqn1ftfbf70tz
🔗 Quantum fluctuations as cosmic seeds (Mukhanov) arxiv.org/abs/astro-ph/0303077
🔭 Evidence: Fluctuations precisely measured in CMB by Planck and WMAP, and confirmed by large-scale galaxy surveys like DESI. DESI Project desi.lbl.gov
#Cosmology #Inflation #BigBang #PrimordialBlackHoles #QuantumPhysics #Astrophysics

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Suzanne Aldrich (she/her)

🚀 Clip 2: False Vacuum Expansion
Here we depict exponential growth driven by the false vacuum’s immense potential energy—space expanded faster than the speed of light, increasing by a factor of at least ~10⁶⁰ in ~10⁻³⁶ seconds. This rapid inflation resolves problems like flatness and horizon issues, as proposed by Guth and further developed by Andrei Linde and Paul Steinhardt.
🎬 Watch the full-res Sora videos here! sora.com/g/gen_01jqmdevs9fpbtt
🔗 Cosmic Inflation theory (Linde, Steinhardt) scientificamerican.com/article
🔭 Evidence: Measurements of flatness and isotropy from WMAP & Planck satellites. NASA WMAP map.gsfc.nasa.gov
#Cosmology #Inflation #BigBang #PrimordialBlackHoles #QuantumPhysics #Astrophysics

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