The universe has different time zones

This supernova remnant that's about 16,000 light years from Earth is from a particular class of supernovae called type Ia that astronomers use to measure cosmic distances. (University of Texas/Chandra X-ray Observatory/NASA)

There's a cosmic controversy brewing in the universe. It centers around the mysterious force known as "dark energy."

This concept emerged from observations of distant supernovae that, in the late 1990s, seemed to indicate the universe had been expanding at a faster and faster pace ever since the big bang. Astronomers made these observations from a certain type of supernovae that explode in such a way that allows astronomers to calculate their distance from us.

The picture emerging from that data didn't fit with previous explanations of the universe that theorized its expansion, driven by the big bang, would eventually slow down as gravity took over. This led scientists to come up with the idea that a force they called "dark energy" pushed against gravity to make the universe expand faster and faster, in keeping with the supernovae data.     READ MORE...

AI Models Big Bang

Researchers from the Flatiron Institute and collaborators have developed an innovative method that uses artificial intelligence (AI) to estimate the universe's cosmological parameters with unprecedented precision. This breakthrough could reshape how scientists study the cosmos.


The method, called Simulation-Based Inference of Galaxies (SimBIG), extracts hidden insights from galaxy distributions, offering a significant improvement over traditional techniques.


By leveraging AI, the team reduced uncertainty in key parameters, such as the universe’s matter clumpiness, to less than half that of conventional methods. This enhanced accuracy aligns closely with other observations, including measurements of the universe’s oldest light, further validating the approach.


Published in Nature Astronomy, the findings promise to advance our understanding of the universe's fundamental properties.     READ MORE...

An Anti-Universe Twin

Our universe has an anti-universe twin moving backwards in time, study finds

Seconds after the Big Bang, the Universe exhibited an astonishing simplicity. Observations reveal a spatially flat, radiation-dominated cosmos described by a Friedmann–Robertson–Walker (FRW) metric. This early state included small, Gaussian, and nearly scale-invariant scalar perturbations.

However, there is no evidence for primordial vector or tensor perturbations, nor for cosmic defects. These observations align with the prevailing inflationary model, which suggests that an era of rapid expansion preceded the Universe's observable state.


Despite its utility, inflation theory introduces complexities and arbitrary parameters, which many physicists view as unnecessary. A team led by Neil Turok and Latham Boyle challenges this conventional framework, offering an alternative grounded in the symmetry of the Universe itself.         READ MORE...

Ancient Galaxies Challenging Cosmic Theories

The James Webb Space Telescope (JWST), the largest and most advanced space telescope ever constructed, has been making remarkable discoveries since its launch in December 2021. Among its achievements is the identification of the earliest and most distant galaxies known, which formed just 300 million years after the Big Bang.

When we observe distant objects in space, we are also looking far back in time. This is because the light from these objects takes billions of years to reach our telescopes. Through the JWST, astronomers have detected several of these ancient galaxies, providing us a glimpse of the universe as it appeared shortly after its inception.

Surprising Brightness of Early Galaxies
The data collected by the JWST aligns well with existing theories of cosmology—the study of the universe’s origin and evolution—and galaxy formation. However, these observations have also brought some surprises. Notably, many of these early galaxies are much brighter than expected, challenging previous assumptions about galaxy brightness and activity shortly after the Big Bang.     READ MORE...

Galaxy with Impossible Light Signature

This region of space, viewed first iconically by Hubble and later by JWST, shows an animation that switches between the two. Both images still have fundamental limitations, as they were acquired from within our inner Solar System, where the presence of zodiacal light influences the noise floor of our instruments and cannot easily be removed. The extra presence of point-like red objects in JWST images, also known as “little red dots,” has finally been explained, but other puzzles still remain.






Since its launch in December of 2021, the James Webb Space Telescope (JWST) has spotted record-setting objects all across the Universe, including at the greatest distances ever seen.

Many distant galaxies are energetic and show signatures of emission lines from specific atoms and molecules, particularly hydrogen. However, the Lyman-α line has never been seen earlier than 550 million years after the Big Bang.

Until now. With the discovery and spectroscopic follow-up on galaxy JADES-GS-z13-1-LA, we now have strong evidence for that emission line from a galaxy just 326 million years after the Big Bang. The question is: how?              READ MORE...

A Star Older Than the Universe

For as long as humans have contemplated the Universe, we’ve marveled at the vastness of it all. Was our Universe infinite? Was it eternal? Or did it spring into existence a finite amount of time ago? Over the 20th and 21st centuries, these existential questions for all-time have, one-by-one, fallen into the realm of science, and now have the best answers we’ve ever been able to assemble. 

As of today, in 2024, we can confidently state that we actually know how old the Universe is: 13.8 billion years old, marking time at the start of the hot Big Bang. If we could step back through time, we’d find that the universe as we know it was a very different place early on. Modern stars and galaxies arose from a series of gravitational mergers of smaller-mass objects, which themselves consisted of younger, more pristine stars. 

At the earliest times, there were no stars or galaxies, and even farther, no neutral atoms or stable atomic nuclei, going all the way back to the hot Big Bang. Today, astronomers and astrophysicists who study the early universe confidently state its age with an uncertainty of no more than ~1%: a remarkable achievement.      READ MORE...

Deciphering the Dark

Dark energy’s role in propelling the universe’s accelerated expansion presents a pivotal challenge in astrophysics, driving ongoing research and space missions dedicated to uncovering the nature of this mysterious force.

Some 13.8 billion years ago, the universe began with a rapid expansion we call the Big Bang. After this initial expansion, which lasted a fraction of a second, gravity started to slow the universe down. But the cosmos wouldn’t stay this way. Nine billion years after the universe began, its expansion started to speed up, driven by an unknown force that scientists have named dark energy.

But what exactly is dark energy?  The short answer is: We don’t know. But we do know that it exists, it’s making the universe expand at an accelerating rate, and approximately 68.3 to 70% of the universe is dark energy.     READ MORE...

Einstein Was Wrong About Gravity

Einstein's theory of gravity—general relativity—has been very successful for more than a century. However, it has theoretical shortcomings. This is not surprising: the theory predicts its own failure at spacetime singularities inside black holes—and the Big Bang itself.

Unlike physical theories describing the other three fundamental forces in physics—the electromagnetic and the strong and weak nuclear interactions—the general theory of relativity has only been tested in weak gravity.

Deviations of gravity from general relativity are by no means excluded nor tested everywhere in the universe. And, according to theoretical physicists, deviation must happen.

Deviations and quantum mechanics
According to a theory initially proposed by Georges Lemaître and widely accepted by the astronomical community, our universe originated in a Big Bang. 

Other singularities hide inside black holes: Space and time cease to have meaning there, while quantities such as energy density and pressure become infinite. These signal that Einstein's theory is failing there and must be replaced with a more fundamental one.

Naively, spacetime singularities should be resolved by quantum mechanics, which apply at very small scales.

Quantum physics relies on two simple ideas: point particles make no sense; and the Heisenberg uncertainty principle, which states that one can never know the value of certain pairs of quantities with absolute precision—for example, the position and velocity of a particle. 

This is because particles should not be thought of as points but as waves; at small scales they behave as waves of matter.  READ MORE...

Star Older Then Universe

The star HD 140283 has been called the "Methuselah star" for its extreme age. At an estimated over 14 billion years old, it’s the oldest star we know, at least within our galaxy. A star that old is certainly interesting, particularly when it is so close to us it can be seen with binoculars, however, that appears to put it older than the universe. How that can be? A closer examination reveals the star is special, but not that special.


The standard estimate of the time since the Big Bang is 13.79 billion years. The figure is derived from the rate of expansion of the universe using Einstein's relativity but has been validated through a variety of methods. However, that number is now facing at least three distinct challenges. As evidence, proponents point to the existence of stars estimated to be either older than 13.8 billion years, or so close to that age that there shouldn’t have been time for them to form.


Not surprisingly HD 140283 gets prime billing (helped by its catchy nickname derived from a Biblical ancestor of Noah said to have lived to 969) due to a 2013 study using Hubble data that estimated it is 14.46 billion years old, plus or minus 800 million years. That would make it potentially older than the universe.


The biggest claim regarding HD 140283 is that it disproves the Big Bang. After all, if there is even one star 14.5 billion years old then the explosion that started the universe couldn’t have happened less than 14 billion years ago. The Big Bang is now so central to our cosmology that were it to be disproved it would create a scientific revolution the like of which we have not seen for a long time.


A smaller, but still dramatic, change would be required to adapt to the recent claim that the Big Bang happened, but almost twice as long ago as most estimates put it, at 26.7 billion years ago.


Neither of these views has much support among astrophysicists, but some do suspect we’ve got our estimates of the timing of the Big Bang more modestly wrong, and the universe is really around 15 billion years old. Although such an estimate would raise a few questions about why our estimates for the universe’s expansion rate are out, if proven, accompanying changes to our thinking would be evolutionary not revolutionary.

In that context, it’s worth asking: if the universe was 26 billion years old, wouldn’t we expect to find 20 billion-year-old stars? It’s true we’ve only really looked across a small portion of the galaxy, but if the universe is that old, Methuselah looks suspiciously young. Then take that question a step further and ask what we might expect to see if the universe had no beginning and has always been here.  READ MORE...

Coldest Matter in The Universe

An illustration shows trapped ytterbium atoms cooled to temperatures about 3 billion times 

colder than deep space (Image credit: Ella Maru Studio/Courtesy of K. Hazzard/Rice University)

A team of researchers has cooled matter to within a billionth of a degree of absolute zero, colder than even the deepest depths of space ,  far away from any stars.


Interstellar space never gets this cold due to the fact that it is evenly filled with the cosmic microwave background (CMB), a form of radiation left over from an event that occurred shortly after the Big Bang when the universe was in its infancy. 

The chilled matter is even colder than the coldest known region of space, the Boomerang Nebula, located 3,000 light-years from Earth, which has a temperature of just one degree above absolute zero.

The experiment, run at the University of Kyoto in Japan and used fermions, which is what particle physicists call any particle that makes up matter, including electrons, protons and neutrons. 

The team cooled their fermions — atoms of the element ytterbium — to around a billionth of a degree above absolute zero, the hypothetical temperature at which all atomic movement would cease.

"Unless an alien civilization is doing experiments like these right now, anytime this experiment is running at Kyoto University it is making the coldest fermions in the universe," Rice University researcher Kaden Hazzard, who took part in the study, said in a statement(opens in new tab).  READ MORE...

New Webb Telescope Observations

Let’s start with the rumors. What about the new Webb data would suggest the big bang is wrong? 

The same type of data Hubble gave us years ago. We generally think of evidence for the big bang being centered around two facts: first, that more distant galaxies have a higher redshift than closer ones; and second, that the universe is filled with a cosmic background of microwave radiation.

The first suggests that the universe is expanding in all directions, while the second suggests that it was once in a very hot and dense state. 

These are two of the Three Pillars of data supporting the big bang, the third being the relative abundance of elements in the early universe.

But these observations are just the foundation of the big bang model. We have long since expanded on these to create the standard model of cosmology, also known as the LCDM model. 

That is a universe that began with the big bang and is filled with matter, dark matter, and dark energy. Everything from the acceleration of cosmic expansion to the clustering of galaxies supports this standard model. 

And the standard model makes predictions about other observational tests, so we can further prove its validity. That’s where the latest claims of the “big bust” come into play.  READ MORE...

The Big Bang Means Something Different Now

If there’s one hallmark inherent to science, it’s that our understanding of how the Universe works is always open to revision in the face of new evidence. 

Whenever our prevailing picture of reality — including the rules it plays by, the physical contents of a system, and how it evolved from its initial conditions to the present time — gets challenged by new experimental or observational data, we must open our minds to changing our conceptual picture of the cosmos. 

This has happened many times since the dawn of the 20th century, and the words we use to describe our Universe have shifted in meaning as our understanding has evolved.

Yet, there are always those who cling to the old definitions, much like linguistic prescriptivists, who refuse to acknowledge that these changes have occurred. 

But unlike the evolution of colloquial language, which is largely arbitrary, the evolution of scientific terms must reflect our current understanding of reality. 

Whenever we talk about the origin of our Universe, the term “the Big Bang” comes to mind, but our understanding of our cosmic origins have evolved tremendously since the idea that our Universe even had an origin, scientifically, was first put forth. 

Here’s how to resolve the confusion and bring you up to speed on what the Big Bang originally meant versus what it means today.  READ MORE...

Webb Telescope Shatters Records

The very first results from the James Webb Space Telescope seem to indicate that massive, luminous galaxies had already formed within the first 250 million years after the Big Bang. If confirmed, this would seriously challenge current cosmological thinking. For now, however, that’s still a big “if.”

Shortly after NASA published Webb’s first batch of scientific data, the astronomical preprint server arXiv was flooded with papers claiming the detection of galaxies that are so remote that their light took some 13.5 billion years to reach us. Many of these appear to be more massive than the standard cosmological model that describes the universe’s composition and evolution.

“It worries me slightly that we find these monsters in the first few images,” says cosmologist Richard Ellis (University College London).

Young, massive stars in newborn galaxies emit vast amounts of energetic ultraviolet radiation. As this light moves through expanding space for billions of years, the wavelengths stretch (redshift) all the way into the infrared – radiation that Webb’s instruments are sensitive to.

It takes careful spectroscopic measurements – either by Webb’s spectrometers or by the ground-based ALMA observatory that operates at even longer wavelengths – to precisely determine the redshifts, which tells you how far out into space — and thus how far back in time — you’re looking. But there’s a quick (albeit less reliable) workaround that gives a rough idea.

Neutral hydrogen atoms in intergalactic space absorb ultraviolet radiation at wavelengths shorter than 91.2 nanometers. For remote objects, this threshold also redshifts to longer wavelengths, into the infrared for the most distant galaxies. 

Since Webb’s near-infrared camera NIRCam takes measurements through a large number of filters, each covering a different wavelength band, a galaxy may be visible in some channels but not in others. The wavelength band in which the galaxy disappears roughly indicates its redshift, and the corresponding look-back time.  READ MORE...

A Galaxy Deeper Back in Time

Data from the Webb Space Telescope has only gotten into the hands of astronomers over the last few weeks, but they've been waiting for years for this, and apparently had analyses set to go. The result has been something like a race back in time, as new discoveries find objects that formed ever closer to the Big Bang that produced our Universe. 

Last week, one of these searches turned up a galaxy that was present less than 400 million years after the Big Bang. This week, a new analysis has picked out a galaxy as it appeared only 233 million years after the Universe popped into existence.

The discovery is a happy byproduct of work that was designed to answer a more general question: How many galaxies should we expect to see at different time points after the Big Bang?

Back in time
As we mentioned last week, the early Universe was opaque to light at any wavelengths that carry more energy than is needed to ionize hydrogen. That energy is in the UV portion of the spectrum, but the red shift caused by 13 billion years of an expanding Universe has shifted that cutoff point into the infrared portion of the spectrum. 

To find galaxies from this time, we have to look for objects that aren't visible at shorter infrared wavelengths (meaning that light was once above the hydrogen cutoff), but do appear at lower-energy wavelengths.

The deeper into the infrared the boundary between invisible and visible is, the stronger the redshift, and the more distant the object is. The more distant the object, the closer in time it is to the Big Bang.  READ MORE...

Backwards in Time

If the universe has a twin and on that twin time runs backward, then scientists could explain dark matter. (Image credit: MARK GARLICK/SCIENCE PHOTO LIBRARY/Getty Images)

A wild new theory suggests there may be another "anti-universe," running backward in time prior to the Big Bang.

The idea assumes that the early universe was small, hot and dense — and so uniform that time looks symmetric going backward and forward.

If true, the new theory means that dark matter isn't so mysterious; it's just a new flavor of a ghostly particle called a neutrino that can only exist in this kind of universe. And the theory implies there would be no need for a period of "inflation" that rapidly expanded the size of the young cosmos soon after the Big Bang.

If true, then future experiments to hunt for gravitational waves, or to pin down the mass of neutrinos, could answer once and for all whether this mirror anti-universe exists.

Preserving symmetry
Physicists have identified a set of fundamental symmetries in nature. The three most important symmetries are: charge (if you flip the charges of all the particles involved in an interaction to their opposite charge, you'll get the same interaction); parity (if you look at the mirror image of an interaction, you get the same result); and time (if you run an interaction backward in time, it looks the same).

Physical interactions obey most of these symmetries most of the time, which means that there are sometimes violations. But physicists have never observed a violation of a combination of all three symmetries at the same time. If you take every single interaction observed in nature and flip the charges, take the mirror image, and run it backward in time, those interactions behave exactly the same.

This fundamental symmetry is given a name: CPT symmetry, for charge (C), parity (P) and time (T).  READ MORE...

From the Dawn of Time

The particle was produced inside the Large Hadron Collider at CERN. (Image credit: Shutterstock)

Physicists at the world's largest atom smasher have detected a mysterious, primordial particle from the dawn of time.

About 100 of the short-lived "X" particles — so named because of their unknown structures — were spotted for the first time amid trillions of other particles inside the Large Hadron Collider (LHC), the world's largest particle accelerator, located near Geneva at CERN (the European Organization for Nuclear Research).

These X particles, which likely existed in the tiniest fractions of a second after the Big Bang, were detected inside a roiling broth of elementary particles called a quark-gluon plasma, formed in the LHC by smashing together lead ions. By studying the primordial X particles in more detail, scientists hope to build the most accurate picture yet of the origins of the universe. They published their findings Jan. 19 in the journal Physical Review Letters.
wie X particle's internal structure, which could change our view of what kind of material the universe should produce."

Scientists trace the origins of X particles to just a few millionths of a second after the Big Bang, back when the universe was a superheated trillion-degree plasma soup teeming with quarks and gluons — elementary particles that soon cooled and combined into the more stable protons and neutrons we know today.

Just before this rapid cooling, a tiny fraction of the gluons and the quarks collided, sticking together to form very short-lived X particles. The researchers don't know how elementary particles configure themselves to form the X particle's structure. But if the scientists can figure that out, they will have a much better understanding of the types of particles that were abundant during the universe's earliest moments.  READ MORE...

Laniakea Destroyed by Dark Energy

On the largest cosmic scales, planet Earth appears to be anything but special. Like hundreds of billions of other planets in our galaxy, we orbit our parent star; like hundreds of billions of solar systems, we revolve around the galaxy; like the majority of galaxies in the Universe, we’re bound together in either a group or cluster of galaxies. 

And, like most galactic groups and clusters, we’re a small part of a larger structure containing over 100,000 galaxies: a supercluster. Ours is named Laniakea: the Hawaiian word for “immense heaven.”

Superclusters have been found and charted throughout our observable Universe, where they’re more than 10 times as rich as the largest known clusters of galaxies. Unfortunately, owing to the presence of dark energy in the Universe, these superclusters ⁠— including our own ⁠— are only apparent structures. In reality, they’re mere phantasms, in the process of dissolving before our very eyes.

The Universe as we know it began some 13.8 billion years ago with the Big Bang. It was filled with matter, antimatter, radiation, etc.; all the particles and fields that we know of today, and possibly even more. 

From the earliest instants of the hot Big Bang, however, it wasn’t simply a uniform sea of these energetic quanta. Instead, there were tiny imperfections ⁠— at about the 0.003% level ⁠— on all scales, where some regions had slightly more or slightly less matter and energy than average.

In each one of these regions, a great cosmic race ensued. The race was between two competing phenomena:

1. the expansion of the Universe, which works to drive all the matter and energy apart
2. gravitation, which works to pull all forms of energy together, causing massive material to clump and cluster together

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Violating Speed of Light

Just 13.8 billion years after the hot Big Bang, we can see 46.1 billion light-years away in all directions. Doesn't that violate...something?

A visual history of the expanding Universe includes the hot, dense state known as the Big Bang and the growth and formation of structure subsequently. The full suite of data, including the observations of the light elements and the cosmic microwave background, leaves only the Big Bang as a valid explanation for all we see. (Credit: NASA/CXC/M. Weiss)

The cardinal rule of relativity is that there's a speed limit to the Universe, the speed of light, that nothing can break.And yet, when we look at the most distant of objects, their light has been traveling for no more than 13.8 billion years, but appears much farther away.Here's how that doesn't break the speed of light; it only breaks our outdated, intuitive notions of how reality ought to behave.

If there’s one rule that most people know about the Universe, it’s that there’s an ultimate speed limit that nothing can exceed: the speed of light in a vacuum. If you’re a massive particle, not only can’t you exceed that speed, but you’ll never reach it; you can only approach the speed of light. If you’re massless, you have no choice; you can only move at one speed through spacetime: the speed of light if you’re in a vacuum, or some slower speed if you’re in a medium. The faster your motion through space, the slower your motion through time, and vice versa. There’s no way around these facts, as they’re the fundamental principle on which relativity is based.

And yet, when we look out at distant objects in the Universe, they seem to defy our common-sense approach to logic. Through a series of precise observations, we’re confident that the Universe is precisely 13.8 billion years old. The most distant galaxy we’ve seen so far is presently 32 billion light-years away; the most distant light we see corresponds to a point presently 46.1 billion light-years away; and galaxies beyond about 18 billion light-years away can never be reached by us, even if we sent a signal at the speed of light today.

Still, none of this breaks the speed of light or the laws of relativity; it only breaks our intuitive notions of how things ought to behave. Here’s what everyone should know about the expanding Universe and the speed of light.  READ MORE...

Big Bang Isn't the Beginning

The modern cosmic picture of our universe’s history begins not with a singularity, the Big Bang, 

but rather with a period of cosmic inflation that stretches a flat, uniform universe. The end of 

inflation is the onset of Hot Big Bang., Nicole Rager Fuller/National Science Foundation)

KEY TAKEAWAYS

• The Big Bang teaches us that our expanding, cooling universe used to be younger, denser, and hotter in the past.
• However, extrapolating all the way back to a singularity leads to predictions that disagree with what we observe.
• Instead, cosmic inflation preceded and set up the Big Bang, changing our cosmic origin story forever.

Where did all this come from? In every direction we care to observe, we find stars, galaxies, clouds of gas and dust, tenuous plasmas, and radiation spanning the gamut of wavelengths: from radio to infrared to visible light to gamma rays. No matter where or how we look at the universe, it’s full of matter and energy absolutely everywhere and at all times. 

And yet, it’s only natural to assume that it all came from somewhere. If you want to know the answer to the biggest question of all — the question of our cosmic origins — you have to pose the question to the universe itself, and listen to what it tells you.

Today, the universe as we see it is expanding, rarifying (getting less dense), and cooling. Although it’s tempting to simply extrapolate forward in time, when things will be even larger, less dense, and cooler, the laws of physics allow us to extrapolate backward just as easily. Long ago, the universe was smaller, denser, and hotter. 

How far back can we take this extrapolation? Mathematically, it’s tempting to go as far as possible: all the way back to infinitesimal sizes and infinite densities and temperatures, or what we know as a singularity. This idea, of a singular beginning to space, time, and the universe, was long known as the Big Bang.

But physically, when we looked closely enough, we found that the universe told a different story. Here’s how we know the Big Bang isn’t the beginning of the universe anymore.  READ MORE...

The Big Band IS NOT the Beginning

The Big Bang teaches us that our expanding, cooling universe used to be younger, denser, and hotter in the past...

However, extrapolating all the way back to a singularity leads to predictions that disagree with what we observe...

Instead, cosmic inflation preceded and set up the Big Bang, changing our cosmic origin story forever...

Where did all this come from? In every direction we care to observe, we find stars, galaxies, clouds of gas and dust, tenuous plasmas, and radiation spanning the gamut of wavelengths: from radio to infrared to visible light to gamma rays. No matter where or how we look at the universe, it’s full of matter and energy absolutely everywhere and at all times. 

And yet, it’s only natural to assume that it all came from somewhere. If you want to know the answer to the biggest question of all — the question of our cosmic origins — you have to pose the question to the universe itself, and listen to what it tells you.

Today, the universe as we see it is expanding, rarifying (getting less dense), and cooling. Although it’s tempting to simply extrapolate forward in time, when things will be even larger, less dense, and cooler, the laws of physics allow us to extrapolate backward just as easily. 

Long ago, the universe was smaller, denser, and hotter. How far back can we take this extrapolation? Mathematically, it’s tempting to go as far as possible: all the way back to infinitesimal sizes and infinite densities and temperatures, or what we know as a singularity. 

This idea, of a singular beginning to space, time, and the universe, was long known as the Big Bang.

But physically, when we looked closely enough, we found that the universe told a different story. Here’s how we know the Big Bang isn’t the beginning of the universe anymore.  READ MORE...