Cosmology

The remnants of Tycho's Type Ia supernova as imaged by the Chandra X-ray Observatory

Database of 2,884 supernovae adds clues to possible change in dark energy

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Researchers reanalyzed three decades of observations and combined two large surveys; interpretation of results still depends on the analysis method, and the study has not yet been peer-reviewed
A field of distant galaxies whose chemistry helps measure the amount of primordial helium

New helium measurement probes the first five minutes of the universe

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Observations of 15 metal-poor galaxies have reduced the uncertainty in the estimate of the amount of primordial helium to 0.5%—about a third of what it was previously.
Why does time only move forward? The arrow of time – Why does time only move forward? Caption: A broken glass illustrates the arrow of time: We repeatedly see objects break and scatter, but we do not see the fragments come together on their own back to their original state. ALT: Illustration of the arrow of time using a whole glass, breaking and reconnecting in the opposite direction Description: Illustration of the arrow of time and entropy. While the process of breaking the glass is familiar from everyday life, the reverse process is possible in principle at the level of many laws of motion but extremely improbable in a macroscopic system. Filename: arrow-of-time-entropy-broken-glass.png Credit: Created using artificial intelligence

Why does time only move forward?

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Most of the basic laws of physics don't distinguish simply between past and future. So why doesn't a broken glass reconnect, why does heat flow from hot to cold and not the other way around, and why do we remember yesterday?
The rate of star formation in the universe has plummeted—but the main fuel pool has hardly disappeared.

The rate of star formation in the universe has plummeted—but the main fuel pool has hardly disappeared.

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Combined FAST and DESI measurements show that over the past 4.5 billion years, the rate of star formation has slowed sharply, while the pool of atomic hydrogen has shrunk only slightly. The finding draws attention to the stage when the gas
The largest 2D sky map includes nearly four billion objects

The largest 2D sky map includes nearly four billion objects

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The map, made up of 263,407 exposures taken over 2,285 nights and containing 5.6 trillion pixels, covers about 75% of the sky and is used by DESI to select galaxies and quasars for 3D mapping of the universe and to study dark energy.
Model: Additional gravitational force between dark matter particles may actually suppress the growth of structures in the universe

Model: Additional gravitational force between dark matter particles may actually suppress the growth of structures in the universe

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The study does not discover a new force, but rather examines a family of models in which dark matter particles are attracted to each other by a hidden field. Contrary to expectations, the additional attraction does not necessarily create a more lumpy universe,
More than half a million galaxies in the picture: Rubin Observatory opens the COSMOS field to science

More than half a million galaxies in the picture: Rubin Observatory opens the COSMOS field to science

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The image, created by combining hundreds of observations from the LSST camera, also contains more than 50 stars. Its release is accompanied by the observatory's first science catalog based on the giant camera, as part of a data preview.
Hidden fifth dimension may create natural dark matter resonance

Hidden fifth dimension may create natural dark matter resonance

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A new theoretical model suggests that the geometry of a compact extra dimension naturally determines the ratio of the masses of a dark matter particle and a dark photon. The resulting resonance may explain how dark matter
Cosmological Hint: Dark Matter and Neutrinos May Interact

Cosmological Hint: Dark Matter and Neutrinos May Interact

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Combining observations of the cosmic microwave background radiation and the weak gravitational lensing effect found a preference of almost three standard deviations for a model in which momentum is transferred between dark matter and neutrinos. The interaction may explain why matter in the universe
James Webb observation of the protocluster SPT2349-56 and the galaxy C26 with a long gas tail

Ancient galaxy caught as environment robs it of raw material for star formation

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Observations by the James Webb Space Telescope and the ALMA array have revealed a massive galaxy in a young protocluster, only about 1.4 billion years after the Big Bang, with more than half of its reservoir of cold gas already pushed out.
Simulation of a quasar powered by matter falling into a supermassive black hole

Euclid Space Telescope Discovers the Earliest Quasars Ever Observed

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The Euclid Space Telescope has helped discover 31 quasars from the early universe, 14 of them at redshifts of 7 or greater. The two most distant were observed as they were about 670 million years after the Big Bang, and again
Type Ia supernova. Credit: Nasa Sciemce

Dark energy still stands the test: New analysis strengthens the accelerating expansion of the universe

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Diagram of a contracting universe undergoing a cosmic jump, leaving behind remnant black holes

Black holes from before the Big Bang? Cosmological model suggests ancient location “fossils”

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Theoretical research suggests that the universe went through a phase of contraction before it began to expand. Black holes and gravitational waves that survived the transition may explain some of the dark matter and the early appearance of black holes.
Comparison between a simulation of the universe in the ΛCDM model and a simulation including massive neutrinos and corrected gravity.

Artificial intelligence learned the laws of the universe – then struggled to identify new physics

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Researchers trained a neural network first on the standard cosmological model and then on models that included massive neutrinos, corrected gravity, and primitive non-Gaussianity. The method saved expensive simulations, but in some cases caused “transfer”
Gravitational waves. Illustration: depositphotos.com

What do gravitational wave detectors really measure when the entire universe changes?

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Researchers have developed a computational framework that connects cosmological relativity with what a real detector actually measures. The method could aid in the search for Joule gravitational waves and faint signals from the early universe.
Hubble Space Telescope image of Supernova 1994D (SN1994D) in the galaxy NGC 4526. Supernova SN 1994D is the bright spot on the lower left. Credit: NASA/ESA.

The universe is still accelerating: New study rejects claim that cosmic expansion has begun to slow down

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An international team, including Nobel laureates Adam Ries and Brian Schmidt, found that the claim that dark energy is weakening was based on an incorrect age estimate of supernovae and the omission of a common correction in the mass
Space-time network. Illustration: depositphotos.com

Tiny black holes may form from space-time 'crystals'

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Researchers have presented a mathematical formula for a theoretical process in which space-time organizes itself into a cyclical pattern. A small addition of energy could transform this unstable state into a tiny black hole.
Astronomers have discovered a massive galaxy from the early universe that appears to not be rotating. (Artist's impression). Illustration: depositphotos.com

Webb Space Telescope Detects Ancient, Nearly Rotationless Galaxy

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A massive galaxy formed less than two billion years after the Big Bang does not show an orderly rotation, contrary to expectations from models of galaxy formation. An ancient merger with another galaxy may have disrupted its motion.
A slice of the COSMOS-Web map, showing galaxies across nearly 14 billion years of the universe's history. The vertex on the left indicates the current time; moving outward, each galaxy is located at its own distance in cosmic time, until you reach a time when the universe was less than a billion years old. Light yellow areas show the dense clusters and filaments of the cosmic web, and dark areas indicate the nearly empty spaces between them. Credit: Hossein Hatamnia, UC Riverside

James Webb Space Telescope reveals sharpest map of the cosmic web

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The COSMOS-Web survey, the largest survey ever conducted with the James Webb Space Telescope, allows astronomers to track galaxies within nebulae, clusters, and cosmic voids across nearly 13.7 billion years of history.
A thin slice of the map created by DESI's five-year survey shows galaxies and quasars above and below the plane of the Milky Way. Credit: Claire Lamman/DESI collaboration

The largest 3D map of the universe has been completed and will help study dark energy

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A record-breaking 3D map of the universe has been completed, giving scientists a new way to study dark energy. The vast data could reveal surprising changes in how the universe is expanding.
The experimental equipment built and used by the students. Credit: Nabil Salama and Agit Akgümüs

Students built a dark matter detector and set new experimental boundaries

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A compact experiment at the University of Hamburg searched for axions, one of the main candidates for dark matter, and showed that even small arrays can contribute to particle physics.
The motion of galaxy clusters reveals the strength of gravity on a scale of hundreds of millions of light years. Credit: Lucy Reading / Simons Foundation

Newton's law of gravity faces unprecedented cosmic test

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Hubble voltage. Illustration: NSF Noir Lab

Extremely precise measurement of the expansion rate of the universe strengthens the “Hubble tension”

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An international collaboration has once again found that the local universe is expanding faster than the standard cosmological model predicts, possibly hinting at new physics.
Weak gravitational waves from the early universe may hint at how dark matter first formed. Illustration: depositphotos.com

Gravitational waves from the early universe may have created dark matter

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A new paper suggests that a weak background of stochastic gravitational waves from the early universe created low-mass particles that may have later become the dark matter that shapes galaxies and large cosmic structures.
Graphics: N. BURGESS/SCIENCE; Data: NASA; Satellite Image: STEVEN RODNEY/UNIVERSITY OF SOUTH CAROLINA; GABRIEL BRAMMER/COSMIC DAWN CENTER/NIELS BOHR INSTITUTE/UNIVERSITY OF COPENHAGEN; Image Processing: JOSEPH DEPASQUALE/STSCI

Cosmic illusions may decide the debate over the rate of expansion of the universe

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An expected reappearance of the supernova SN Requiem, seen repeatedly due to gravitational lensing, may provide a third way to measure the Hubble constant.
Dark matter. Illustration: depositphotos.com

The mystery deepens: New model suggests dark matter is not made up of one type of particle

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A study published in Science Bulletin suggests that self-interacting two-component dark matter could explain both the sparse cores of dwarf galaxies and the dense gravitational lensing structures observed in the universe.
Black hole. Illustration: depositphotos.com

Is the universe infinite? What does science really know about the shape of the universe?

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Measurements of the cosmic microwave background radiation indicate that the observable universe is approximately flat, but scientists still do not know whether the entire universe is infinite, finite without an edge, or has a more complex topological structure.
Astronomers have discovered an unusual gravitationally stimulated supernova whose light traveled more than 10 billion years to reach Earth. Illustration: depositphotos.com

Rare Excited Supernova May Help Decipher the Rate of Expansion of the Universe

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The event SN 2025wny, seen through gravitational lensing after a journey of more than ten billion years, may provide a new measurement of the Hubble constant and contribute to the understanding of dark energy.
Sunset, just before the Vera Rubin Telescope begins nighttime operations. Photo courtesy of NSF

The Rubin Observatory's giant camera is underway, and its goal is: "To answer one question - what is the universe?"

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The Vera Rubin Observatory has begun publishing its first discoveries – supernovae, variable stars and asteroids – ahead of the launch of the Legacy Survey of Space and Time (LSST), a ten-year sky survey.
The universe is full of dark energy. Illustration: Avi Blizovsky via DALEE

The cosmic spaces are not empty, they are filled with dark energy.

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Even the most sparse regions of the universe are not "nothing." According to quantum field theory, they are filled with vacuum energy, and it is there that the expansion of the universe accelerates.
A combination of infrared and X-rays reveals a nascent cluster with hot gas – already a billion years after the Big Bang. From the article in Nature.

Galaxy cluster at the beginning of the universe: Webb and Chandra found hot gas earlier than expected

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The two space telescopes revealed a nascent galaxy cluster (“protocluster”) in which a hot gas cloud emitting X-rays also appears, a sign of “virial heating” and advanced gravitational collapse – already when the universe was about a billion years old.
Computer simulation showing baby black holes growing in a young galaxy in the early universe. Credit: Dr John Regan

New simulations offer a solution: This is how black holes grew quickly to become supermassive in the early universe

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Simulation study claims that the young universe was chaotic and rich in dense gas, allowing even “light seeds” to undergo “binge” episodes that exceeded conventional growth limits
Suyanov-Zeldovich effect. Credit: Lingxiao Yuan

Extremely hot intracluster gas discovered in young galaxy cluster – earlier than predicted

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ALMA measurement and the Sonyaev-Zeldovich effect indicate “overheating” about 1.4 billion years after the Big Bang, challenging models of galaxy cluster formation
A gravitational lens distorts objects behind it. Illustration: depositphotos.com

Mysterious object challenges simple models of dark matter

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An unusual observational case: an object with a mass of a million solar masses, which has no clear “parallel” among known objects, may be the result of a collision between different types of dark matter
A gravitational lens distorts objects behind it. Illustration: depositphotos.com

Mysterious object challenges accepted dark matter models

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Gravitational lensing analysis points to a body “the size of a million suns” with a structure unlike any known object – and may hint that dark matter is not as “smooth” as we thought
Image of the expansion of the universe created by artificial intelligence. Credit: ZARM, Universität Bremen (AI generated)

What if dark energy doesn't exist? New theory could rewrite the expansion of the universe

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Researchers suggest that the accelerating expansion of the universe could be due to the geometry of space-time and the extension of the theory of gravity – without adding a “mysterious element” to the equations to match observations
The world in 2050. Illustration: Avi Blizovsky via DALEE.

The journal "Nature" looks to 2050: Nuclear fusion, Mars, and "lightless" laboratories – and it all depends on politics

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The prestigious journal marks the decisive junctures: the climate crisis and the response to it, the race for artificial intelligence infrastructure, questions of public trust and science funding, and the ability to transform breakthroughs into systems that work at scale.
Dark matter distorts space-time. Illustration: depositphotos.com

New code allows simulation of the “hidden life” of dark matter within galactic halos

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Researchers at the Perimeter Institute have developed KiSS-SIDM, a computational tool that bridges intermediate regimes in a model of self-interacting dark matter, and may improve the understanding of core collapse and even the formation of black holes.
An illustration illustrating the rotation of neutral hydrogen (right) in galaxies located in an elongated galaxy (middle), with the galaxies showing a coherent overall rotational motion that follows the large-scale cosmic fabric (left).

One of the largest rotating structures ever seen: a giant cosmic filament where galaxies spin “in the same direction”

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Artist's impression of material spiraling inward, pulled by the strong gravity of a central supermassive black hole, forming an "accretion disk." Credit: Dimitrios Sakkas (tomakti), Antonis Georgakakis, Angel Ruiz, Maria Chira (NOA)

New observations: The relationship between UV and X-ray radiation in quasars has changed over cosmic time

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International research finds that the long-standing correlation between UV and X-ray emissions from quasars is not constant throughout the history of the universe – a hint that the structure of the accretion disk and “corona” around supermassive black holes is not universal
Faint radio glow from the early universe may hold hidden clues about the first stars. Illustration: depositphotos.com

13-billion-year-old radio signal may reveal the first stars in the universe

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An international team led by the University of Cambridge shows that the 21-centimeter signal from hydrogen atoms at cosmic dawn is sensitive to the mass of the first stars (Population III), and that the REACH and SKA radio observatories will be able to map how the universe evolved.
Type Ia supernova - is the universe slowing down? Illustration: depositphotos.com

Is the universe slowing down?

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The Big Bang Theory. Illustration: depositphotos.com

Study: “Cannibal Stars” and Primordial Black Holes Could Have Formed in the First Second After the Big Bang

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A cosmological model suggests that during a brief matter-dominant period immediately after inflation, halos of particles formed that gravitationally-thermally collapsed to form primordial black holes (PBHs), boson stars, and “cannibal stars” that prevent mutual annihilation of particles —
Neutrinos are created as a byproduct of nuclear fusion, such as that which occurs inside stars. Illustration: depositphotos.com

Will neutrinos reveal why the universe exists?

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A collaboration between two leading neutrino experiments, NOVA in the US and T2K in Japan, paints the most precise picture yet of neutrino oscillations – and may come closer to explaining why the universe is full of matter and not
Researchers have built a small but powerful detector to find gravitational waves in a hidden frequency range. The discovery could reveal unseen black hole activity and echoes from the early universe. Illustration: depositphotos.com

The small device that will open a new window to the universe: a compact gravitational wave detector for the millihertz range

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UK researchers present a desktop detector based on optical resonators and atomic clocks, which opens access to the “middle domain” of gravitational waves and could reveal binary white dwarfs, black hole mergers and a stochastic background – and a bridge
Does dark matter change the color of light? Illustration: depositphotos.com

According to a new theory, we've been looking for dark matter the wrong way.

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But the York researchers say the light may change its color slightly depending on the type of dark matter it encounters. If this theory is confirmed, this effect could provide a new way to study the hidden component.
LIGO Gravitational Wave Observatory in the US, credit: caltech

A new model of the Big Bang incorporates gravitational waves and seeks to change our understanding of the beginning of the universe.

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Scientists propose that gravitational waves shaped the universe. Their model challenges the cosmic inflation model
Baryon acoustic oscillations represent the sound of the Big Bang. Credit: Gabriela Secara, Perimeter Institute, CC BY-SA

New measurements suggest we may be living in a giant "cosmic void"

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New research suggests we may reside in a local cosmic void – a region devoid of galaxies and matter – which could explain the rapid expansion of the universe relative to the Standard Model predictions and provide a solution
An artist's impression of CAPERS-LRD-z9, home to the earliest confirmed black hole. The supermassive black hole at its center is thought to be surrounded by a thick cloud of gas, giving the galaxy its distinctive red color. Credit: Erik Zumalt, The University of Texas at Austin

Webb Telescope Discovers Oldest Black Hole – Breaking Universe Records

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Astronomers using the James Webb Space Telescope have detected the oldest confirmed supermassive black hole, found in a rare "Little Red Spot" galaxy and formed just 500 million years after the Big Bang.
Prof. Ron Margolin, Tel Aviv University. Screenshot.

Podcast: The Great Mysteries of Science – Is There Intelligence in the Universe? (Episode 4)

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Prof. Ron Margolin of Tel Aviv University on meaning, the laws of nature, and whether the universe is “directed” — from Tel Aviv 360, Tel Aviv University’s podcast channel (Hebrew only)
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