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Category: cosmology

Black-hole solutions in quantum gravity with Vilkovisky-DeWitt effective action

Physicists propose that calculations of certain aspects of quantum gravity can currently be done even without a full theory of quantum gravity itself. Basically, they work backwards from the fact that quantum gravity on the macro scale must conform to Einstein’s relativity theories. This approach is effective until the small scale of a black hole singularity is close.

(See my Comment below for an article link to POPULAR MECHANICS that discussed the scientific article in an accessible manner.

We study new black-hole solutions in quantum gravity. We use the Vilkovisky-DeWitt unique effective action to obtain quantum gravitational corrections to Einstein’s equations. In full analogy to previous work done for quadratic gravity, we find new black-hole–like solutions. We show that these new solutions exist close to the horizon and in the far-field limit.

Is Earth inside a huge void? ‘Sound of the Big Bang’ hints at possible solution to Hubble tension

Earth and our entire Milky Way galaxy may sit inside a mysterious giant hole which makes the cosmos expand faster here than in neighboring regions of the universe, astronomers say.

Their theory is a potential solution to the “Hubble tension” and could help confirm the true age of our universe, which is estimated to be around 13.8 billion years old.

The latest research —shared at the Royal Astronomical Society’s National Astronomy Meeting (NAM 2025) at Durham University—shows that sound waves from the early universe, “essentially the sound of the Big Bang,” support this idea.

Stars That Shouldn’t Shine Are Pointing Straight to Dark Matter’s Identity

Deep in the center of our galaxy, scientists believe a strange type of star may be quietly glowing—not from fusion like our Sun, but from the invisible fuel of dark matter.

These “dark dwarfs” could act like cosmic detectors, collecting heavy, elusive particles that heat them from the inside. If we find them—and especially if we spot one missing its lithium—it could finally point us toward what dark matter really is.

Dark dwarfs & dark matter basics

Dark dwarfs lurking at the center of our galaxy might hint at the nature of dark matter

Celestial objects known as dark dwarfs may be hiding at the center of our galaxy and could offer key clues to uncover the nature of one of the most mysterious and fundamental phenomena in contemporary cosmology: dark matter.

A paper published in the Journal of Cosmology and Astroparticle Physics by a team of researchers based in the UK and Hawaii describes these objects for the first time and proposes how to verify their existence using current observational tools such as the James Webb Space Telescope. The paper is titled “Dark Dwarfs: Dark Matter-Powered Sub-Stellar Objects Awaiting Discovery at the Galactic Center.”

The Anglo-U.S. team behind the study named them dark dwarfs. Not because they are dark bodies—on the contrary—but because of their special link with dark matter, one of the most central topics in current cosmology and astrophysics research.

Radio signal from the very early universe offers clues about the first stars

Understanding how the universe transitioned from darkness to light with the formation of the first stars and galaxies is a key turning point in the universe’s development, known as the Cosmic Dawn. However, even with the most powerful telescopes, we can’t directly observe these earliest stars, so determining their properties is one of the biggest challenges in astronomy.

Now, an international group of astronomers led by the University of Cambridge has shown that we will be able to learn about the masses of the earliest stars by studying a specific radio signal—created by hydrogen atoms filling the gaps between star-forming regions—originating just a hundred million years after the Big Bang.

By studying how the first stars and their remnants affected this signal, called the 21-centimeter signal, the researchers have shown that future radio telescopes will help us understand the very early universe, and how it transformed from a nearly homogeneous mass of mostly hydrogen to the incredible complexity we see today. Their results are reported in the journal Nature Astronomy.

Machine learning outpaces supercomputers for simulating galaxy evolution coupled with supernova explosion

Researchers have used machine learning to dramatically speed up the processing time when simulating galaxy evolution coupled with supernova explosion. This approach could help us understand the origins of our own galaxy, particularly the elements essential for life in the Milky Way.

The findings are published in The Astrophysical Journal.

The team was led by Keiya Hirashima at the RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) in Japan, along with colleagues from the Max Planck Institute for Astrophysics (MPA) and the Flatiron Institute.

Could AI help us better understand the universe?

For almost as long as humans have existed, we have been trying to make sense of the cosmos. What started as philosophical musing has, following the advent of the telescope and the ability to look ever farther into space (and ever earlier in time), become a thriving field of research.

Today, scientists seek to understand the properties governing how our universe behaves. These properties are characterized mathematically as so-called cosmological parameters, which fit into our models of the cosmos. The more precisely these parameters can be measured, the better we are able to differentiate between models, as well as validate — or rule out — long-held theories, including Einstein’s general theory of relativity. Because different models can hold vastly different predictions for both our universe’s earliest moments and eventual fate, that differentiation is vital.

To date, some of the biggest challenges include more tightly constraining parameters such as those that determine the precise amount and nature of dark matter, the source of dark energy and the repulsive force that it exerts, and exactly how neutrinos behave.

New Quantum Data Suggests The Butterfly Effect Operates on Galactic Scale

Could a single quantum ripple have shaped the entire universe? This video uncovers the groundbreaking evidence behind the cosmic butterfly effect—where microscopic quantum events influence galaxies, black holes, and even the fate of time itself.

In this episode, we explore how quantum fluctuations during cosmic inflation may have triggered the formation of the Milky Way, why black holes are the most chaotic systems in existence, and how recent discoveries in entanglement, chaos theory, and entropy are rewriting the rules of reality.

🔍 Featuring insights from:

Physical Review Letters (2024): Quantum simulations proving micro-changes alter entire universes.

MIT’s Cosmic Bell Test: Entanglement confirmed over billions of light years.

Physicists Close In on the Fifth Force That Could Unlock the Mystery of Dark Matter

Scientists are using trapped ions in cutting-edge experiments to hunt for signs of an undiscovered particle that might help unravel the mystery of dark matter. The Standard Model of particle physics offers an exceptionally precise description of the fundamental components that form all visible ma

Growing evidence for evolving dark energy could inspire a new model of the universe

The birth, growth and future of our universe are eternally fascinating.

In the last decades, telescopes have been able to observe the skies with unprecedented precision and sensitivity.

Our research team on the South Pole Telescope is studying how the universe evolved and has changed over time. We have just released two years’ worth of mapping of the infant universe over 1/25th of the sky.