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Category: cosmology – Page 3

What If Dark Matter Is Just Black Holes?

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It may be that for every star in the universe there are billions of microscopic black holes streaming through the solar system, the planet, even our bodies every second. Sounds horrible — but hey, at least we’d have explained dark matter.

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In Quantum Gravity, the Cosmological Constant May Behave Similar To The Quantum Hall Effect

So why not do the same thing for a gravitational field? Well, it turns out that quantum renormalization only works for Euclidean space. In general relativity, the mass-energy of a system warps space and time. So all those quantum fluctuations curve spacetime, and curved spacetime induces even more virtual particles, which warp space even more… oh no! It all breaks down, and we can’t quantize gravitational fields the way we quantize the other fundamental forces.

Problems like these have led some researchers to develop a model known as loop quantum gravity. Rather than trying to calculate the behavior of quantum particles in a timey-wimey background, why not treat the entire mass-energy-spacetime structure as a single quantum system? It’s like imagining the Universe within an unseen background that is Euclidean. This way the problem of renormalization can be overcome in many cases. One case where it doesn’t work well is the cosmological constant. In most cosmological models, the cosmological constant is what drives cosmic expansion. Since it is a universal dark energy field, it amplifies the loop quantum gravity sums, and once again the whole thing diverges. You can handle this by fixing the cosmological constant to a specific value, but that isn’t really a solution to the problem. It’s the cosmology equivalent of ignoring the engine light in your car…

A new study finds this might not be too bad after all. In it, the authors demonstrate an interesting similarity between the cosmological constant in loop quantum gravity and the quantum Hall effect in standard quantum theory.

Physicists find evidence that the universe isn’t perfectly uniform — potentially unraveling a 100-year-old model of cosmology

The universe may not be perfectly uniform after all, a new series of papers hints. If confirmed, this could upend a nearly 100-year-old model of cosmology.

JWST spots two early black holes growing far faster than their galaxies

Astronomers have discovered two early-universe galaxies where the central black holes appear to have grown far faster than their host galaxies. Observations with the James Webb Space Telescope (JWST) reveal that the black holes in these galaxies, seen just 800 million years after the Big Bang, are significantly more massive relative to their host galaxies, as opposed to what astronomers see in the nearby universe. The study is published on the arXiv preprint server.

Astronomers have long discovered quasars—extraordinarily luminous galaxies powered by accreting black holes weighing billions of solar masses—in the first billion years of the universe. For these to exist so early, the black holes must have started as large as heavy seeds and grown at their maximum rate possible for most of their lives. These early black holes appear oversized compared to the galaxies they live in.

On the other hand, when JWST began its operation in 2022, it made a huge splash in astronomy with the discovery of an astonishingly large number of mature galaxies and black holes in the first billion years of the universe. Among them were some “overmassive” black holes weighing billions of times the mass of our sun, but rarely as massive as those found in luminous quasars.

How a single star can reshape an entire galaxy

Astronomers who simulate galaxies do not always get the same result, even when they start from identical conditions. New research from Leiden University shows that this is not a flaw, but a consequence of how galaxies behave—and how they are modeled.

The findings offer, for the first time, a way to address a long-standing question: how chaotic is a galaxy like the Milky Way really? The computer simulations by Tetsuro Asano and Simon Portegies Zwart (Leiden Observatory) will soon be published in Astronomy & Astrophysics and are available now on the arXiv preprint server.

The researchers created hundreds of models of Milky Way-like galaxies: flat disks of stars, embedded in a large, invisible cloud of dark matter that holds the system together. In each experiment, they ran two almost identical simulations, differing by just one tiny detail—for instance, a small shift in the position of a single star. Over time, that slight difference grows into visible structural changes: the spiral arms develop differently and the central bar rotates in another way.

Unexplored interactions between electrons and atomic nuclei shed light on dark matter

Dark matter particles could be mediators of the interaction between electrons and atomic nuclei, as shown by a study conducted by junior group leader, Dr. Konstantin Gaul, Dr. Lei Cong, and Professor Dr. Dmitry Budker, of Johannes Gutenberg University Mainz (JGU), Helmholtz Institute Mainz (HIM) and the PRISMA++ Cluster of Excellence. Their work, published last week in Physical Review Letters, presents new constraints on previously unexplored candidates for dark matter and, more generally, some hypothetical particles that are not included in the Standard Model of particle physics ℠.

Using results from precision measurements on barium monofluoride (BaF) molecules, the team constrained these interactions mediated by Z’ bosons for the first time. Z’ bosons are hypothetical mediators of the weak interaction and possible dark matter particles in several SM extensions. “These results address a significant blind spot in physics: a regime of forces between electrons and nuclei that had remained unexplored by both laboratory experiments and cosmological data,” explained Gaul.

Our universe is made up of about 4% of visible, or ordinary, matter. This includes planets, stars, and life on Earth. The remaining 96% of the universe is invisible and consists of dark matter and dark energy, with dark matter making up about 23%. Astrophysical observations confirm its presence throughout the cosmos, where it, for example, plays an important part in the structure of galaxies. However, we don’t know what particles make up dark matter. Many theories and ongoing experiments are looking for an answer to this open question.

Radio telescopes confirm 3.3-million-light-year halo in unusually quiet galaxy cluster

Astronomers have employed the upgraded Giant Metrewave Radio Telescope (uGMRT) and the MeerKAT radio telescope to observe a galaxy cluster known as RXCJ0232–4420. Results of the new observations, published April 29 on the arXiv pre-print server, deliver important insights into the nature of this cluster.

Galaxy clusters contain up to thousands of galaxies bound together by gravity. They generally form as a result of mergers and grow by accreting sub-clusters. Therefore, they could serve as excellent laboratories for studying galaxy evolution and cosmology.

The 20 Different Types of Faster-Than-Light (FTL) Travel In Fiction

What if humanity could travel faster than light?

In this cinematic deep dive, we explore the different types of FTL (Faster-Than-Light) travel, including warp drives, wormholes, the Alcubierre drive, hyperdrive concepts, and other theoretical methods that could one day change space exploration forever.

From bending spacetime to creating warp bubbles and bridging distant galaxies, this video breaks down the science, theory, and science-fiction inspirations behind each method — in a realistic and visually immersive way.

Whether you’re a fan of space science, futuristic technology, or sci-fi universes, this is your ultimate guide to FTL travel.

🚀 Which method do you think is the most realistic?
Comment below!

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Versions of You in Other Universes May Be Subtly Affecting Your Destiny, Oxford Physicist Says

You may think you’re the protagonist of your own story. According to Oxford physicist Vlatko Vedral, however, you’re more like a puppet — whose strings are being pulled into a million parallel universes at any given time.

As Vedral argues in a recent issue of Popular Mechanics, the pop-sci version of the “observer effect” — where the act of observation or measurement affects a system — gets the cause-and-effect backward. The typical story goes something like this: quantum objects hang out in multiple states at once, until some observer glances over. At this point, the multiple states collapse and only one is left, an assumption that can lead various woo-woo interpretations, like that we create reality simply by observing it.

Physics, Verdal says, does not support that idea. That collapse effect isn’t a special power of human consciousness, but rather a fact of physics that says interactions — any interaction — forces a quantum system to commit to a definite state.

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