<![CDATA[Scivillage.com Casual Discussion Science Forum - Astrophysics, Cosmology & Astronomy]]>

<![CDATA[Scivillage.com Casual Discussion Science Forum - Astrophysics, Cosmology & Astronomy]]> https://www.scivillage.com/ Mon, 15 Jun 2026 04:21:24 +0000 MyBB <![CDATA['Crisis averted' as experts confirm universe's expansion is accelerating]]> https://www.scivillage.com/thread-20619.html Thu, 11 Jun 2026 20:19:56 +0000 C C]]> https://www.scivillage.com/thread-20619.html https://ras.ac.uk/news-and-press/researc...celerating

INTRO: Our universe's expansion is still accelerating despite recent claims suggesting otherwise, an international team of astrophysicists say.

They refuted a study published last year claiming the growth of the universe is slowing and insist there is no flaw in the widely-accepted theory that a mysterious force known as dark energy is driving the expanding cosmos.

The researchers, who include two Nobel Laureates and represent institutions worldwide, say the debate that followed last November’s revelations was the result of a scientific misunderstanding rather than a cosmic grenade threatening to blow apart everything we know about the universe.

Their paper has been published today in Monthly Notices of the Royal Astronomical Society.

It is a direct rebuttal of a study by a team of South Korean researchers that made the erroneous claim the universe's expansion may have entered a deceleration phase, caused by the influence of dark energy – which acts as a kind of anti-gravity – weakening over time.

"The previous and well accepted measurements were, in fact, fine and our current understanding of the fate of the universe remains robust," said lead author Dr Phil Wiseman, from the University of Southampton.

"Thankfully we have averted this crisis, but the mystery about why the rate of expansion of the universe is still accelerating remains. By proving our measurements are correct, we can get back to trying to understand what this dark energy actually is, rather than wondering if it exists at all." (MORE - no ads)]]> https://ras.ac.uk/news-and-press/researc...celerating

INTRO: Our universe's expansion is still accelerating despite recent claims suggesting otherwise, an international team of astrophysicists say.

They refuted a study published last year claiming the growth of the universe is slowing and insist there is no flaw in the widely-accepted theory that a mysterious force known as dark energy is driving the expanding cosmos.

The researchers, who include two Nobel Laureates and represent institutions worldwide, say the debate that followed last November’s revelations was the result of a scientific misunderstanding rather than a cosmic grenade threatening to blow apart everything we know about the universe.

Their paper has been published today in Monthly Notices of the Royal Astronomical Society.

It is a direct rebuttal of a study by a team of South Korean researchers that made the erroneous claim the universe's expansion may have entered a deceleration phase, caused by the influence of dark energy – which acts as a kind of anti-gravity – weakening over time.

"The previous and well accepted measurements were, in fact, fine and our current understanding of the fate of the universe remains robust," said lead author Dr Phil Wiseman, from the University of Southampton.

"Thankfully we have averted this crisis, but the mystery about why the rate of expansion of the universe is still accelerating remains. By proving our measurements are correct, we can get back to trying to understand what this dark energy actually is, rather than wondering if it exists at all." (MORE - no ads)]]> <![CDATA[Astrobiology's looming statistical crisis + Our model can work without dark energy]]> https://www.scivillage.com/thread-20564.html Tue, 02 Jun 2026 19:55:50 +0000 C C]]> https://www.scivillage.com/thread-20564.html Can our model of the cosmos work without dark energy? New research says it can
https://gizmodo.com/can-our-model-of-the...2000765968

INTRO: In a new paper published last week in Proceedings of the Royal Society A, though, a team of researchers demonstrate how the problem of accelerated expansion might be more a matter of current cosmological models being based on instabilities that do not translate very well into observable reality.

“Unstable solutions in physics and science are considered not physical,” Blake Temple, the study’s co-author and a mathematician at University of California, Davis (UC Davis), said in a statement. “You’ll never observe them in nature.” (MORE - details)

Astrobiology's looming statistical crisis
https://www.universetoday.com/articles/a...cal-crisis

EXCERPT: In Bayesian statistics, the kind used by most astronomers, when you don’t know the likelihood of something happening, you use what’s called a “diffuse prior”. Essentially, you tell the math - I have no idea how common life is, and I also have no idea how likely this signal is being generated by some process that I don’t understand is non-biological in nature. The problem, as Dr. Kipping shows in his paper, is that when you do that, the math gets quickly out of control.

In order to reach a Bayesian factor of 10 (meaning the evidence for life is 10 times stronger than the evidence for no life), the number of planets to be surveyed ranges from a mere 12,366 to a whopping 44 trillion. Keep in mind that these planets have to all have the same signature being analyzed - that’s how the statistics works. Also keep in mind that, as of the time of writing, we have only found around 6,200 confirmed exoplanets. In other words, we would need to double our total stock of confirmed exoplanets, and all of those exoplanets would have to have the exact same signal of potential biosignatures in order to meet the actual statistical requirements of definitively detecting life.

To put it bluntly - that’s not going to happen any time soon. And Dr. Kipping makes that point in the paper. Though he does offer a solution that sounds like it’s stolen straight from Silicon Valley’s playbook - A/B testing. To do this for exoplanet analysis, he suggests splitting a group of exoplanets with the same potentially interesting signal into two groups, but with a key feature - both groups have to have the same false positive rate. That would mean that, mathematically at least, that “unknown confounder” would cancel out, making the comparison between the two groups more direct at least.

Fraser discusses the possibility of finding certain molecules that stand out as biosignatures, and what other processes might create them.
While the math behind that is elegant, it faces a huge hurdle in reality - how do you find two groups of planets where “life” behaves differently but the unknown chemistry that could be driving the signals we’re interpreting as life behaves exactly the same across all planets.

To put it bluntly, the likelihood of that happening is almost as remote as us finding 44 trillion exoplanets in the next 25 years. So, it appears that the 25 exoplanets that the Habitable Worlds Observatory plans to survey when it is launched next year is only a drop in the statistical bucket of what data we would need to collect to prove life definitively exists on another planet... (MORE - missing details)]]> <![CDATA[Why the most massive galaxies in the early Universe stopped forming stars prematurely]]> https://www.scivillage.com/thread-20535.html Fri, 29 May 2026 00:28:14 +0000 C C]]> https://www.scivillage.com/thread-20535.html https://www.eurekalert.org/news-releases/1130005

EXCERPTS: Astronomical observations show that the most massive galaxies in the early Universe formed approximately 3 to 4 billion years after the Big Bang and stopped producing stars very early in cosmic history, around 1 billion years after their formation. This strange behavior has puzzled experts in the field. For comparison, our galaxy, the Milky Way, is as old as the Universe itself and continues to produce stars, albeit at a low rate, even 13.5 billion years after its formation.

A study conducted at the Institute of Astronomy, Geophysics, and Atmospheric Sciences at the University of São Paulo (IAG-USP) in Brazil, in collaboration with international partners and published in the journal Astronomy & Astrophysics, proposes a consistent solution to this problem.

“We focused on two seemingly distinct populations: dusty star-forming galaxies [DSFGs] and massive quiescent galaxies [MQs],” says Laerte Sodré Júnior, a retired full professor, former director of IAG-USP, and doctoral advisor to the lead author of the study, Pablo Araya-Araya.

[...] The study proposes that each progenitor galaxy of an MQ underwent an early and violent merger with a galaxy of similar mass. This catastrophic event triggered two simultaneous processes: an extreme burst of star formation and rapid growth of a supermassive black hole in the central region. “The merger of the two galaxies concentrated large amounts of gas in the core, simultaneously triggering an extreme burst of star formation and intense feeding of the supermassive black hole,” Sodré summarizes.

“In that process, the cold gas is rapidly consumed while the energy released by the active nucleus heats the surrounding halo gas and prevents it from cooling and being reincorporated into the galaxy, blocking the supply of raw material for new stars and halting star formation in less than one billion years,” the scientist explains.

In contrast, most star- and dust-forming galaxies grow more gradually through long-term processes. Significant mergers only occur at later stages, resulting in slower gas consumption and eventual late extinction of star formation, which is observed at lower redshifts.

[...] Recent operations of the James Webb Space Telescope have helped map DSFGs. At the same time, they revealed a greater-than-expected number of massive, quiescent galaxies in the early Universe.

The proposed model has not yet fully resolved the problem, as there are still discrepancies between predictions and observations. “We’re observing far more galaxies with submillimeter emissions than we predicted,” Sodré admits.

Nevertheless, the study provides a coherent framework for explaining the evolution of DSFGs into MQs based on galaxy mergers, bursts of star formation, and the formation of supermassive black holes... (MORE - missing details, no ads)]]> https://www.eurekalert.org/news-releases/1130005

EXCERPTS: Astronomical observations show that the most massive galaxies in the early Universe formed approximately 3 to 4 billion years after the Big Bang and stopped producing stars very early in cosmic history, around 1 billion years after their formation. This strange behavior has puzzled experts in the field. For comparison, our galaxy, the Milky Way, is as old as the Universe itself and continues to produce stars, albeit at a low rate, even 13.5 billion years after its formation.

A study conducted at the Institute of Astronomy, Geophysics, and Atmospheric Sciences at the University of São Paulo (IAG-USP) in Brazil, in collaboration with international partners and published in the journal Astronomy & Astrophysics, proposes a consistent solution to this problem.

“We focused on two seemingly distinct populations: dusty star-forming galaxies [DSFGs] and massive quiescent galaxies [MQs],” says Laerte Sodré Júnior, a retired full professor, former director of IAG-USP, and doctoral advisor to the lead author of the study, Pablo Araya-Araya.

[...] The study proposes that each progenitor galaxy of an MQ underwent an early and violent merger with a galaxy of similar mass. This catastrophic event triggered two simultaneous processes: an extreme burst of star formation and rapid growth of a supermassive black hole in the central region. “The merger of the two galaxies concentrated large amounts of gas in the core, simultaneously triggering an extreme burst of star formation and intense feeding of the supermassive black hole,” Sodré summarizes.

“In that process, the cold gas is rapidly consumed while the energy released by the active nucleus heats the surrounding halo gas and prevents it from cooling and being reincorporated into the galaxy, blocking the supply of raw material for new stars and halting star formation in less than one billion years,” the scientist explains.

In contrast, most star- and dust-forming galaxies grow more gradually through long-term processes. Significant mergers only occur at later stages, resulting in slower gas consumption and eventual late extinction of star formation, which is observed at lower redshifts.

[...] Recent operations of the James Webb Space Telescope have helped map DSFGs. At the same time, they revealed a greater-than-expected number of massive, quiescent galaxies in the early Universe.

The proposed model has not yet fully resolved the problem, as there are still discrepancies between predictions and observations. “We’re observing far more galaxies with submillimeter emissions than we predicted,” Sodré admits.

Nevertheless, the study provides a coherent framework for explaining the evolution of DSFGs into MQs based on galaxy mergers, bursts of star formation, and the formation of supermassive black holes... (MORE - missing details, no ads)]]> <![CDATA[Scientists find the Universe has multiple ways of manufacturing black holes]]> https://www.scivillage.com/thread-20519.html Tue, 26 May 2026 18:14:49 +0000 C C]]> https://www.scivillage.com/thread-20519.html https://www.eurekalert.org/news-releases/1129641

EXCERPTS: . . . Some might form as one giant cloud of gas that collapses to give two massive stars that then become black holes. Others might be black holes that wander into each other in dense environments called clusters that are packed with stars. While others are the product of a previous generation of mergers between two black holes,” Dr Banagiri said.

The paper, released as a preprint, found that there is a presence of multiple sub-populations of merging black holes that can potentially arise from different formation pathways.

Assistant Professor of physics at Princeton University, Sylvia Biscoveanu, co-author of the study and previously a Fulbright postgraduate scholar at Monash University, commented on the unprecedented scale of the catalog update.

“GWTC-5 represents the largest single increase in the size of the gravitational-wave catalog, including events with remarkable properties such as GW241127, which contains BHs of very different masses with clearly wobbling orbits due to tilted spins. The new catalog also contains the event with the best localisation on the sky to date, GW240615.”

The researchers also found that some of these black holes are spinning very rapidly. These fast spinning black holes have two different sets of masses; the first set are between 10-20 times the sun’s mass and the second set have masses greater than 45 times the sun’s mass.

“One of the most fascinating things we’ve discovered about these new black holes is that they are spinning very fast. The sun rotates once every 25 days. If it became a black hole and started spinning as quickly as the ones we discovered, it would be rotating several thousand times every second. So where do these rapidly-spinning black holes come from? One leading explanation is that they are 'hierarchical' products of a previous generation of merger between two black holes,” Dr Banagiri said.

The paper identified that black holes which are hierarchical in origin, are more massive than other black holes nearby. By analysing the new data set, the researchers found that the black holes more massive than 45 times the sun, are more likely to merge with lower mass black holes.

The new dataset will provide rich new information about black holes for astronomers and scientists to research... (MORE - missing details, no ads)]]> https://www.eurekalert.org/news-releases/1129641

EXCERPTS: . . . Some might form as one giant cloud of gas that collapses to give two massive stars that then become black holes. Others might be black holes that wander into each other in dense environments called clusters that are packed with stars. While others are the product of a previous generation of mergers between two black holes,” Dr Banagiri said.

The paper, released as a preprint, found that there is a presence of multiple sub-populations of merging black holes that can potentially arise from different formation pathways.

Assistant Professor of physics at Princeton University, Sylvia Biscoveanu, co-author of the study and previously a Fulbright postgraduate scholar at Monash University, commented on the unprecedented scale of the catalog update.

“GWTC-5 represents the largest single increase in the size of the gravitational-wave catalog, including events with remarkable properties such as GW241127, which contains BHs of very different masses with clearly wobbling orbits due to tilted spins. The new catalog also contains the event with the best localisation on the sky to date, GW240615.”

The researchers also found that some of these black holes are spinning very rapidly. These fast spinning black holes have two different sets of masses; the first set are between 10-20 times the sun’s mass and the second set have masses greater than 45 times the sun’s mass.

“One of the most fascinating things we’ve discovered about these new black holes is that they are spinning very fast. The sun rotates once every 25 days. If it became a black hole and started spinning as quickly as the ones we discovered, it would be rotating several thousand times every second. So where do these rapidly-spinning black holes come from? One leading explanation is that they are 'hierarchical' products of a previous generation of merger between two black holes,” Dr Banagiri said.

The paper identified that black holes which are hierarchical in origin, are more massive than other black holes nearby. By analysing the new data set, the researchers found that the black holes more massive than 45 times the sun, are more likely to merge with lower mass black holes.

The new dataset will provide rich new information about black holes for astronomers and scientists to research... (MORE - missing details, no ads)]]> <![CDATA[George Ellis: spacetime is growing & there's no global wave function for a multiverse]]> https://www.scivillage.com/thread-20453.html Sat, 16 May 2026 22:06:29 +0000 C C]]> https://www.scivillage.com/thread-20453.html George Ellis was one of Stephen Hawking's co-authors. He apparently subscribes to his own version of the GBU called the "Evolving Block Universe". While he believes that wave functions are real like Roger Penrose does, he dismisses the idea of a global wave function. Even rejecting a WF corresponding to smaller macroscopic objects like cats and brains.

If time was both structurally existential and endless, then that would seemingly demand a GBU model because infinity is not a completed situation or quantity. However, the existing "past" of a GBU would still be akin to the conventional block universe, and there's no guarantee that we're actually at the growing edge. We could be spatiotemporally located anywhere from minutes to billions of years behind it. Since the standard BU has its own cognitive explanation for the experience of "moving" along it from one different state to the next, that would still apply in the GBU, too. (The appearance of time passing isn't solely dependent on being at the edge of the "magically" enlarging block.)

SPOILER SNIPPET: Ellis stresses that the model is a modification, not a radical overhaul, of the standard view. “This is a block universe with dynamics covered by the general-relativity field equations — absolutely standard — but with a future boundary that is the ever-changing present,” he said.
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CURT JAIMUNGAL (joined by Ellis)
https://youtu.be/wnpYBg008AQ

VIDEO EXCERPTS: We do not live in a block universe, we evolve in an evolving block universe. [...] So my model of the universe is an evolving block universe. In another billion years, that right-hand edge will have moved to the right a billion years. Space-time itself would have grown, space-time would have gotten bigger. And how will that have happened? Well, through the Einstein field equations.

[...] I agree with Roger Penrose that wave function collapse is real, and with my colleague Barbara Drossel I've written papers about what we call contextual wave function collapse. That wave function collapse is real, but the way it happens is always determined by the context, and we give a very detailed example of that in our paper called "Contextual Wave Function Collapse."

So it's an objective collapse theory?

Yeah.

[...] Now, the real universe is not linear, so there's a paradox there. How does nonlinear stuff come out of a totally linear equation? They try to say, "well, it comes from the multiverse."

Well, the real solution comes from looking back to general relativity. The great breakthrough in general relativity occurred when we discovered the concept of coordinate systems. You can't cover an ordinary space-time by a single coordinate system. You have to have a whole atlas of coordinates, and it's the atlas which covers space-time, not a single one, and that's what enabled us to discover all the topological results in general relativity.

Now, what I claim is exactly the same holds in quantum physics. There is no global wave function — that's a fantasy. There are local wave functions everywhere, and the local wave functions cover the whole space-time, but there is no single wave function for a universe, which completely undercuts the whole idea of the quantum multiverse.

There's no wave function for a cat and all that stuff. There's no wave function for a brain. And the idea that one single wave function could encompass a whole brain is purely fantasy. It's obviously nonsense because the key fact of quantum physics is that quantum physics equations are linear.

[...] You think the multiverse is nonsense?

Okay, there are various kinds of multiverses. [...] I'm prepared to believe that some chaotic cosmologies [cosmological inflation] will lead to different expanding universe domains. I'm prepared to believe that. but I'm not an expert in inflationary theory...

Hawking's co-author: "No global wave function" ... https://youtu.be/wnpYBg008AQ

https://www.youtube-nocookie.com/embed/wnpYBg008AQ]]> George Ellis was one of Stephen Hawking's co-authors. He apparently subscribes to his own version of the GBU called the "Evolving Block Universe". While he believes that wave functions are real like Roger Penrose does, he dismisses the idea of a global wave function. Even rejecting a WF corresponding to smaller macroscopic objects like cats and brains.

If time was both structurally existential and endless, then that would seemingly demand a GBU model because infinity is not a completed situation or quantity. However, the existing "past" of a GBU would still be akin to the conventional block universe, and there's no guarantee that we're actually at the growing edge. We could be spatiotemporally located anywhere from minutes to billions of years behind it. Since the standard BU has its own cognitive explanation for the experience of "moving" along it from one different state to the next, that would still apply in the GBU, too. (The appearance of time passing isn't solely dependent on being at the edge of the "magically" enlarging block.)

https://www.youtube-nocookie.com/embed/wnpYBg008AQ]]> <![CDATA[The science in "Project Hail Mary"? Astrophysicist Becky Smethurst chats with G-L-M]]> https://www.scivillage.com/thread-20398.html Sun, 10 May 2026 16:04:23 +0000 C C]]> https://www.scivillage.com/thread-20398.html Project Hail Mary
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#2 Ryan Gosling (Project Hail Mary) chats with astrophysicist Dr Becky ... https://youtu.be/qj_AbV1Ph90

https://www.youtube-nocookie.com/embed/qj_AbV1Ph90

#1 Phil Lord & Chris Miller (Project Hail Mary) chat with astrophysicist Dr Becky ... https://youtu.be/sAWv1_YNWSY

https://www.youtube-nocookie.com/embed/sAWv1_YNWSY]]> Project Hail Mary
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#2 Ryan Gosling (Project Hail Mary) chats with astrophysicist Dr Becky ... https://youtu.be/qj_AbV1Ph90

https://www.youtube-nocookie.com/embed/qj_AbV1Ph90

#1 Phil Lord & Chris Miller (Project Hail Mary) chat with astrophysicist Dr Becky ... https://youtu.be/sAWv1_YNWSY

https://www.youtube-nocookie.com/embed/sAWv1_YNWSY]]> <![CDATA[Non-rotating early galaxy is a surprise to astronomers]]> https://www.scivillage.com/thread-20363.html Mon, 04 May 2026 16:44:23 +0000 C C]]> https://www.scivillage.com/thread-20363.html https://www.eurekalert.org/news-releases/1126708

INTRO: Astronomers using the James Webb Space Telescope have made a surprising discovery about a galaxy long, long ago and far, far away: It isn’t rotating.

That’s something only seen in the most massive, mature galaxies that are closer to us in space and time, said Ben Forrest, a research scientist in the Department of Physics and Astronomy at the University of California, Davis, and first author on the paper published May 4 in Nature Astronomy.

“This one in particular did not show any evidence of rotation, which was surprising and very interesting,” Forrest said. According to current theories, as the first galaxies formed, angular momentum from inflowing gas and the influence of gravity set them spinning.

Over many billions of years, some galaxies, especially those within galaxy clusters, merged with each other multiple times and their combined rotations added to or partly canceled each other. That’s why some galaxies that are closest to Earth (and therefore also relatively recent) can show little overall rotation but a lot of random movement of stars within them.

This process should take an enormously long time, so it’s surprising that galaxy XMM-VID1-2075 had achieved this state when the universe was less than 2 billion years old.

Forrest and colleagues in the MAGAZ3NE (Massive Ancient Galaxies at z>3 NEar-Infrared) survey had previously observed this galaxy with the W.M. Keck observatory in Hawaiʻi.

“Previous MAGAZ3NE observations had confirmed this was one of the most massive galaxies in the early universe, with already several times as many stars as our Milky Way, and also confirmed that it was no longer forming new stars, making it a compelling target for follow-up observations,” Forrest said... (MORE- no ads)]]> https://www.eurekalert.org/news-releases/1126708

INTRO: Astronomers using the James Webb Space Telescope have made a surprising discovery about a galaxy long, long ago and far, far away: It isn’t rotating.

That’s something only seen in the most massive, mature galaxies that are closer to us in space and time, said Ben Forrest, a research scientist in the Department of Physics and Astronomy at the University of California, Davis, and first author on the paper published May 4 in Nature Astronomy.

“This one in particular did not show any evidence of rotation, which was surprising and very interesting,” Forrest said. According to current theories, as the first galaxies formed, angular momentum from inflowing gas and the influence of gravity set them spinning.

Over many billions of years, some galaxies, especially those within galaxy clusters, merged with each other multiple times and their combined rotations added to or partly canceled each other. That’s why some galaxies that are closest to Earth (and therefore also relatively recent) can show little overall rotation but a lot of random movement of stars within them.

This process should take an enormously long time, so it’s surprising that galaxy XMM-VID1-2075 had achieved this state when the universe was less than 2 billion years old.

Forrest and colleagues in the MAGAZ3NE (Massive Ancient Galaxies at z>3 NEar-Infrared) survey had previously observed this galaxy with the W.M. Keck observatory in Hawaiʻi.

“Previous MAGAZ3NE observations had confirmed this was one of the most massive galaxies in the early universe, with already several times as many stars as our Milky Way, and also confirmed that it was no longer forming new stars, making it a compelling target for follow-up observations,” Forrest said... (MORE- no ads)]]> <![CDATA[The universe may end trillions of years sooner than we thought]]> https://www.scivillage.com/thread-20323.html Wed, 29 Apr 2026 14:47:50 +0000 C C]]> https://www.scivillage.com/thread-20323.html https://www.livescience.com/space/cosmol...we-thought

INTRO: Scientists have long assumed our universe would continue on for trillions of years, but a new study presents a much shorter life span for the cosmos: Our universe might last only another 33 billion years.

That's just a cosmic blink before everything collapses in on itself ?—? a process dubbed the "Big Crunch," where expansion reverses, causing all matter and space-time to collapse back into an extremely dense state similar to the conditions of the Big Bang. While long considered a discarded possibility for the fate of the universe, because of accelerating cosmic expansion, this new research has reopened the surprising — and slightly unsettling — option.

The journey to this dramatic conclusion started with our quest to map the cosmos, where we've focused on dark energy, the mysterious force that's pushing the universe apart at an accelerating rate. Recent data from the Dark Energy Survey (DES) and the Dark Energy Spectroscopic Instrument (DESI) mapped hundreds of millions of galaxies to probe this expansion. These crucial tools suggest, with extremely high confidence that the dark energy "equation of state" — its pressure-to-energy density relationship, which dictates its effect on expansion — isn't simply a static number. Instead, its influence appears to be changing over time.

This strange dynamic opens the door for alternative explanations for what dark energy might be made of. This has led to the axion dark energy (aDE) model, which proposes that dark energy comprises both an axion field, which would be an ultra-light form of dark matter that sloshes around the universe, plus a cosmological constant, or fixed background expansion baked into the structure of space-time.

In the new paper, which was uploaded to the preprint server arXiv, the researchers applied this hybrid model to DES measurements... (MORE - details)]]> https://www.livescience.com/space/cosmol...we-thought

INTRO: Scientists have long assumed our universe would continue on for trillions of years, but a new study presents a much shorter life span for the cosmos: Our universe might last only another 33 billion years.

That's just a cosmic blink before everything collapses in on itself ?—? a process dubbed the "Big Crunch," where expansion reverses, causing all matter and space-time to collapse back into an extremely dense state similar to the conditions of the Big Bang. While long considered a discarded possibility for the fate of the universe, because of accelerating cosmic expansion, this new research has reopened the surprising — and slightly unsettling — option.

The journey to this dramatic conclusion started with our quest to map the cosmos, where we've focused on dark energy, the mysterious force that's pushing the universe apart at an accelerating rate. Recent data from the Dark Energy Survey (DES) and the Dark Energy Spectroscopic Instrument (DESI) mapped hundreds of millions of galaxies to probe this expansion. These crucial tools suggest, with extremely high confidence that the dark energy "equation of state" — its pressure-to-energy density relationship, which dictates its effect on expansion — isn't simply a static number. Instead, its influence appears to be changing over time.

This strange dynamic opens the door for alternative explanations for what dark energy might be made of. This has led to the axion dark energy (aDE) model, which proposes that dark energy comprises both an axion field, which would be an ultra-light form of dark matter that sloshes around the universe, plus a cosmological constant, or fixed background expansion baked into the structure of space-time.

In the new paper, which was uploaded to the preprint server arXiv, the researchers applied this hybrid model to DES measurements... (MORE - details)]]> <![CDATA[Seeing the Milky Way in neutrino light]]> https://www.scivillage.com/thread-20287.html Sat, 25 Apr 2026 23:46:35 +0000 Magical Realist]]> https://www.scivillage.com/thread-20287.html
https://www.google.com/search?q=neutrino...MrPD4,st:0]]>
https://www.google.com/search?q=neutrino...MrPD4,st:0]]> <![CDATA[Interstellar comet 3I/ATLAS was born somewhere much different from our solar system]]> https://www.scivillage.com/thread-20269.html Fri, 24 Apr 2026 15:40:58 +0000 C C]]> https://www.scivillage.com/thread-20269.html https://www.eurekalert.org/news-releases/1125362

EXCERPT: “Our new observations show that the conditions that led to the formation of our solar system are much different from how planetary systems evolved in different parts of our galaxy,” said Luis Salazar Manzano, lead author of the new study and a doctoral student in the U-M Department of Astronomy.

Water is made of two hydrogen atoms and one oxygen atom, hence its H2O formula. In typical water molecules, though, those hydrogen atoms have just one proton at their core. In the comet’s water, a high ratio of its water molecules contain deuterium, a form of hydrogen with the standard issue proton plus a neutron. These heavier forms of water also exist on Earth, but in much lower quantities than were observed in 3I/ATLAS.

“The amount of deuterium with respect to ordinary hydrogen in water is higher than anything we’ve seen before in other planetary systems and planetary comets,” Salazar Manzano said. In fact, the ratio was 30 times that of any comet in our solar system, Salazar Manzano said, and 40 times the value found in the water in our oceans.

These ratios tell researchers about the conditions that were present where these celestial objects formed, allowing them to compare the birthplace of 3I/ATLAS with our solar system when planets and comets were forming. In particular, this result means 3I/ATLAS came from somewhere colder and with lower levels of radiation, said Teresa Paneque-Carreño, a co-leader of the new study and U-M assistant professor of astronomy.

“This is proof that whatever the conditions were that led to the creation of our solar system are not ubiquitous throughout space,” Paneque-Carreño said. “That may sound obvious, but it’s one of those things that you need to prove.”

Accomplishing an unprecedented study like this required a lot of things going right, the team said. It started with astronomers discovering 3I/ATLAS early enough to enable follow-up studies, Paneque-Carreño said... (MORE - missing details)]]> https://www.eurekalert.org/news-releases/1125362

EXCERPT: “Our new observations show that the conditions that led to the formation of our solar system are much different from how planetary systems evolved in different parts of our galaxy,” said Luis Salazar Manzano, lead author of the new study and a doctoral student in the U-M Department of Astronomy.

Water is made of two hydrogen atoms and one oxygen atom, hence its H2O formula. In typical water molecules, though, those hydrogen atoms have just one proton at their core. In the comet’s water, a high ratio of its water molecules contain deuterium, a form of hydrogen with the standard issue proton plus a neutron. These heavier forms of water also exist on Earth, but in much lower quantities than were observed in 3I/ATLAS.

“The amount of deuterium with respect to ordinary hydrogen in water is higher than anything we’ve seen before in other planetary systems and planetary comets,” Salazar Manzano said. In fact, the ratio was 30 times that of any comet in our solar system, Salazar Manzano said, and 40 times the value found in the water in our oceans.

These ratios tell researchers about the conditions that were present where these celestial objects formed, allowing them to compare the birthplace of 3I/ATLAS with our solar system when planets and comets were forming. In particular, this result means 3I/ATLAS came from somewhere colder and with lower levels of radiation, said Teresa Paneque-Carreño, a co-leader of the new study and U-M assistant professor of astronomy.

“This is proof that whatever the conditions were that led to the creation of our solar system are not ubiquitous throughout space,” Paneque-Carreño said. “That may sound obvious, but it’s one of those things that you need to prove.”

Accomplishing an unprecedented study like this required a lot of things going right, the team said. It started with astronomers discovering 3I/ATLAS early enough to enable follow-up studies, Paneque-Carreño said... (MORE - missing details)]]> <![CDATA[Space Jellyfish Predictor]]> https://www.scivillage.com/thread-20258.html Thu, 23 Apr 2026 03:29:10 +0000 Yazata]]> https://www.scivillage.com/thread-20258.html
Currently John holds a NASA position created especially for him: Special Communications Assistant to the Administrator of NASA.

And he's been working on this own time creating the Space Jellyfish Predictor.

A Space Jellyfish is the often spectacular sky-show created when a rocket launches right after sunset or right before dawn. As the rocket ascends it leaves the Earth's shadow (we call it 'night') and passes into bright sunlight while the Earth surface below is still in darkness. This creates crazy illumination of the rocket's exhaust plume.

https://jellyfish.johnkrausphotos.com/

John describes the Space Jellyfish Predictor this way -

https://x.com/johnkrausphotos/status/202...3389072590

Quote:Pleased to share the v1 public beta of the Space Jellyfish Predictor, which outputs text predictions and heatmaps for upcoming rocket launches and their potential to produce a “space jellyfish.” This effect occurs when a launch is illuminated by the sun while an observer is in relative local darkness.

You can try it out here: https://jellyfish.johnkrausphotos.com — please report any issues and suggest features in this thread. I am also eager to see real-world photos from upcoming missions at distances close and far to help refine the models.

Especially during this early v1 public beta period, please treat this site as potentially helpful guidance, not a guarantee. In the event of issues, I may pull it down at any time.

How it works:

The model evaluates the geometry between the observer, rocket, and sun to estimate whether a launch plume is likely to be sunlit, how high it may appear above the horizon, and how strongly it may contrast against the sky. It identifies the strongest post-liftoff moment and converts it into a likelihood/prominence label, and does so in increments for two hours on either side of the current T-0 so you have insight into the evolving forecast.

This tool is focused on immediate post-launch ascent visibility and does not model delayed illumination from residual plumes. Nighttime launches can still be visible from great distances, and only sunlit ascents will produce relevant forecasts. As always, real-world conditions (especially weather and atmospheric quality) can affect what is actually visible.

The default location for each launch prediction is the launchpad, which is generally sufficient for nearby viewers. For distant observers, you can change your location to generate a location-specific text output for a given mission.

The site currently supports Starlink missions with strong fidelity across groups, ISS crew/resupply launches, and GTO/similar missions. Other Falcon 9 missions may use a generalized fallback ascent profile once their launch azimuth (direction) is determined, but these predictions will likely be a bit less reliable.

It was fun to work on this outside of the day job. I hope it is useful. If there is strong interest, I will evaluate the feasibility of adding additional vehicle types and launch sites in the weeks ahead.

]]>
Currently John holds a NASA position created especially for him: Special Communications Assistant to the Administrator of NASA.

And he's been working on this own time creating the Space Jellyfish Predictor.

A Space Jellyfish is the often spectacular sky-show created when a rocket launches right after sunset or right before dawn. As the rocket ascends it leaves the Earth's shadow (we call it 'night') and passes into bright sunlight while the Earth surface below is still in darkness. This creates crazy illumination of the rocket's exhaust plume.

https://jellyfish.johnkrausphotos.com/

John describes the Space Jellyfish Predictor this way -

https://x.com/johnkrausphotos/status/202...3389072590

Quote:Pleased to share the v1 public beta of the Space Jellyfish Predictor, which outputs text predictions and heatmaps for upcoming rocket launches and their potential to produce a “space jellyfish.” This effect occurs when a launch is illuminated by the sun while an observer is in relative local darkness.

You can try it out here: https://jellyfish.johnkrausphotos.com — please report any issues and suggest features in this thread. I am also eager to see real-world photos from upcoming missions at distances close and far to help refine the models.

Especially during this early v1 public beta period, please treat this site as potentially helpful guidance, not a guarantee. In the event of issues, I may pull it down at any time.

How it works:

The model evaluates the geometry between the observer, rocket, and sun to estimate whether a launch plume is likely to be sunlit, how high it may appear above the horizon, and how strongly it may contrast against the sky. It identifies the strongest post-liftoff moment and converts it into a likelihood/prominence label, and does so in increments for two hours on either side of the current T-0 so you have insight into the evolving forecast.

This tool is focused on immediate post-launch ascent visibility and does not model delayed illumination from residual plumes. Nighttime launches can still be visible from great distances, and only sunlit ascents will produce relevant forecasts. As always, real-world conditions (especially weather and atmospheric quality) can affect what is actually visible.

The default location for each launch prediction is the launchpad, which is generally sufficient for nearby viewers. For distant observers, you can change your location to generate a location-specific text output for a given mission.

The site currently supports Starlink missions with strong fidelity across groups, ISS crew/resupply launches, and GTO/similar missions. Other Falcon 9 missions may use a generalized fallback ascent profile once their launch azimuth (direction) is determined, but these predictions will likely be a bit less reliable.

It was fun to work on this outside of the day job. I hope it is useful. If there is strong interest, I will evaluate the feasibility of adding additional vehicle types and launch sites in the weeks ahead.

]]> <![CDATA[NASA close-up of Jupiter's surface]]> https://www.scivillage.com/thread-20241.html Tue, 21 Apr 2026 15:38:27 +0000 Magical Realist]]> https://www.scivillage.com/thread-20241.html
"NASA has unveiled one of the closest images ever captured of Jupiter—and the detail is truly stunning.

Swirling cloud patterns, enormous storms, and chaotic bands sweep across the planet, each one far larger than Earth itself. These massive systems have been active for centuries, and many are likely to persist for generations.

A powerful reminder of how intense and ever-changing our Solar System truly is."

]]>
"NASA has unveiled one of the closest images ever captured of Jupiter—and the detail is truly stunning.

Swirling cloud patterns, enormous storms, and chaotic bands sweep across the planet, each one far larger than Earth itself. These massive systems have been active for centuries, and many are likely to persist for generations.

A powerful reminder of how intense and ever-changing our Solar System truly is."

]]> <![CDATA[Planets need more water to support life than scientists previously thought]]> https://www.scivillage.com/thread-20198.html Wed, 15 Apr 2026 20:54:19 +0000 C C]]> https://www.scivillage.com/thread-20198.html https://www.eurekalert.org/news-releases/1124414

INTRO: Unfortunately for science fiction fans, desert worlds outside our solar system are unlikely to host life, according to new research from University of Washington. Scientists show that an Earth-sized planet needs at least 20 to 50% of the water in Earth’s oceans to maintain a critical natural cycle that keeps water on the surface.

Scientists believe that there are billions of planets outside our solar system. More than 6,000 of these exoplanets are confirmed, but only some of them are candidates for life. The search for life has focused on planets in the “habitable zone,” a sweet spot that is neither too close nor too far from a central star. Planets in this zone are considered viable because they can maintain liquid surface water.

“When you are searching for life in the broad landscape of the universe with limited resources, you have to filter out some planets,” said lead author Haskelle White-Gianella, a UW doctoral student of Earth and space sciences.

Water, although essential, does not guarantee the existence of life. With this study, researchers worked to further narrow the search by investigating planets with just a small amount of water.

“We were interested in arid planets with very limited surface water inventory — far less than one Earth ocean. Many of these planets are in the habitable zone of their star, but we weren’t sure if they could actually be habitable,” White-Gianella said.

The team’s results, published April 13 in Planetary Science Journal, show that habitability hinges on the geologic carbon cycle — a water-driven process that exchanges carbon between the atmosphere and interior over millions of years, stabilizing surface temperatures... (MORE - details, no ads)]]> https://www.eurekalert.org/news-releases/1124414

INTRO: Unfortunately for science fiction fans, desert worlds outside our solar system are unlikely to host life, according to new research from University of Washington. Scientists show that an Earth-sized planet needs at least 20 to 50% of the water in Earth’s oceans to maintain a critical natural cycle that keeps water on the surface.

Scientists believe that there are billions of planets outside our solar system. More than 6,000 of these exoplanets are confirmed, but only some of them are candidates for life. The search for life has focused on planets in the “habitable zone,” a sweet spot that is neither too close nor too far from a central star. Planets in this zone are considered viable because they can maintain liquid surface water.

“When you are searching for life in the broad landscape of the universe with limited resources, you have to filter out some planets,” said lead author Haskelle White-Gianella, a UW doctoral student of Earth and space sciences.

Water, although essential, does not guarantee the existence of life. With this study, researchers worked to further narrow the search by investigating planets with just a small amount of water.

“We were interested in arid planets with very limited surface water inventory — far less than one Earth ocean. Many of these planets are in the habitable zone of their star, but we weren’t sure if they could actually be habitable,” White-Gianella said.

The team’s results, published April 13 in Planetary Science Journal, show that habitability hinges on the geologic carbon cycle — a water-driven process that exchanges carbon between the atmosphere and interior over millions of years, stabilizing surface temperatures... (MORE - details, no ads)]]> <![CDATA[Inflation explains universe’s low entropy at birth + Expansion rate doesn't add up]]> https://www.scivillage.com/thread-20166.html Sat, 11 Apr 2026 13:32:39 +0000 C C]]> https://www.scivillage.com/thread-20166.html The local universe’s expansion rate is clearer than ever, but still doesn’t add up
https://www.eurekalert.org/news-releases/1123728

EXCERPT: These two approaches are expected to yield the same result, but they don’t. Measurements based on the nearby Universe consistently indicate a higher expansion rate — around 73 kilometers per second per megaparsec — while predictions derived from the early Universe yield a lower value, closer to 67 or 68. Although the numerical difference is modest, it is far larger than can be explained by statistical uncertainty. This persistent disagreement, known as the Hubble tension, has now been observed across multiple independent studies and techniques... (MORE - missing details, no ads)

PAPER: http://dx.doi.org/10.1051/0004-6361/202557993

Cosmic inflation explains the universe’s low entropy at birth
https://bigthink.com/starts-with-a-bang/...hypothsis/

EXCERPTS: So how, then, did we — very ordered beings — emerge from this chaos? And if entropy has always been increasing, how did the Universe begin with an entropy that’s so much smaller than it is today? That’s the key behind a philosophical conundrum known as the past hypothesis puzzle. While philosophers may lose sleep over it, physicists don’t have to, because cosmic inflation solves it. Here’s how.

[...] here’s where the big question regarding the past hypothesis comes in: if each passing moment brings along with it an increase in entropy, and the entropy of the Universe has always been increasing, and the second law of thermodynamics dictates that entropy must always increase (or remain the same) and can never decrease, then how did our Universe initially start off in such a low-entropy state to begin with?

The answer, perhaps surprisingly, has been known theoretically for more than 40 years: cosmic inflation.

You might think of cosmic inflation in different terms, as either:

the reason the Big Bang occurred,
the additional, now-verified hypothesis of what came before and set up the conditions that the Big Bang was born with,
or as the theory that removed the notion of the “Big Bang singularity” from the notion of the hot, dense, expanding state we identify as the Big Bang.

the reason the Big Bang occurred,
the additional, now-verified hypothesis of what came before and set up the conditions that the Big Bang was born with,
or as the theory that removed the notion of the “Big Bang singularity” from the notion of the hot, dense, expanding state we identify as the Big Bang.

(All are correct in their own ways.) But inflation, although it’s a not-particularly well-appreciated feature of it, by its very nature forces the Universe to be born in a low entropy state, regardless of the conditions from which inflation arose. And even more remarkably, it never once violates the second law of thermodynamics, allowing entropy to never decrease during the process.

How does this occur?

The simplest way to explain it is to introduce two concepts to you that you likely have already heard of, but perhaps don’t have a sufficient appreciation of. The first is the difference between entropy (the total amount you’ll find) and entropy density (the total amount you’ll find in a given volume of space), which sounds easy enough. But the second requires a little bit of an explanation: the concept of adiabatic expansion. Adiabatic expansion is an important property in thermodynamics, in engines, in astrophysical gases and plasmas, and also in the expanding Universe...

[...] In other words, the solution to the problem of the past hypothesis puzzle, or why the Universe possessed a low-entropy state at the start of the hot Big Bang, is because the Universe underwent a period of cosmic inflation. The rapid, relentless, exponential expansion of the Universe took whatever entropy might have pre-existed within a specific region of space — occupying a certain volume of space — and inflated that volume to tremendous quantities.

Even though entropy was conserved (or possibly even increased very, very slightly), the entropy density plummets, as near-constant entropy in an exponentially expanding volume translates to having the entropy in any specific, well-defined volume of space becoming exponentially suppressed. That’s why, if you accept the evidence in favor of cosmic inflation, where that evidence is very, very strong, you no longer have a “past hypothesis” problem. The Universe is simply born with the amount of entropy that the transition from an inflationary state to a hot Big Bang state, a process known as cosmic reheating, imprints upon it.

The Universe was born in a low-entropy state because inflation caused the entropy density to plummet, and only after that did the hot Big Bang occur. Then, as expected, from that initial value, the Universe’s entropy has been forever increasing from that point onward. As long as you remember that entropy is not entropy density, and that inflating any volume while keeping the entropy constant necessarily results in a very small entropy density in the aftermath of that inflationary period, you’ll never be confused by the past hypothesis puzzle again... (MORE - missing details)]]> <![CDATA[Black hole at center of our galaxy may be even stranger]]> https://www.scivillage.com/thread-20158.html Fri, 10 Apr 2026 01:10:50 +0000 C C]]> https://www.scivillage.com/thread-20158.html Scientists thought there was a black hole at the centre of our Galaxy. It turns out it may be something even stranger
https://www.skyatnightmagazine.com/news/...ark-matter

INTRO: Astronomers have proposed a radical alternative to the long-held belief that a supermassive black hole sits at the centre of the Milky Way, suggesting that instead a dense clump of dark matter could generate the same gravitational effects. The new study, published in Monthly Notices of the Royal Astronomical Society, argues that an ultra-compact dark matter core can explain both the rapid motions of stars near our galactic centre and the larger-scale rotation of our Galaxy.

For decades, the object known as Sagittarius A* has been interpreted as a black hole more than four million times the mass of the Sun, largely because stars in its vicinity, called S-stars, whirl around
it at enormous speeds. However, an international team have put forward a fermionic dark matter model that could reproduce the same stellar motions without a black hole.

“This is the first time a dark matter model has successfully bridged these vastly different scales and various object orbits, including modern rotation curve and central stars data,” says the study’s co-author Dr Carlos Argüelles. “We are not just replacing the black hole with a dark object; we are proposing that the supermassive central object and the Galaxy’s dark matter halo are two manifestations of the same substance.” (MORE - details)

Eurekalert (excerpts): The international team of researchers have instead put forward an alternative idea – that a specific type of dark matter made up of fermions, or light subatomic particles, can create a unique cosmic structure that also fits with what we know about the Milky Way's core. It would in theory produce a super-dense, compact core surrounded by a vast, diffuse halo, which together would act as a single, unified entity.

The inner core would be so compact and massive that it could mimic the gravitational pull of a black hole and explain the orbits of S-stars that have been observed in previous studies, as well as the orbits of the dust-shrouded objects known as G-sources which also exist nearby.

Of particular importance to the new research is the latest data from the European Space Agency's GAIA DR3 mission, which has meticulously mapped the rotation curve of the Milky Way's outer halo, showing how stars and gas orbit far from the centre.

It observed a slowdown of our galaxy's rotation curve, known as the Keplerian decline, which the researchers say can be explained by their dark matter model's outer halo when combined with the traditional disc and bulge mass components of ordinary matter.

This, they add, strengthens the 'fermionic' model by highlighting a key structural difference. While traditional Cold Dark Matter halos spread out following an extended 'power law' tail, the fermionic model predicts a tighter structure, leading to more compact halo tails.

[...] "Our model not only explains the orbits of stars and the galaxy's rotation but is also consistent with the famous 'black hole shadow' image. The dense dark matter core can mimic the shadow because it bends light so strongly, creating a central darkness surrounded by a bright ring."

The researchers statistically compared their fermionic dark matter model to the traditional black hole model. They found that while current data for the inner stars cannot yet decisively distinguish between the two scenarios, the dark matter model provides a unified framework that explains the galactic centre (central stars and shadow), and the galaxy at large.

The new study paves the way for future observations. [...] The outcome of these findings could potentially reshape our understanding of the fundamental nature of the cosmic behemoth at the heart of the Milky Way. (MORE - missing details, no ads)]]> Scientists thought there was a black hole at the centre of our Galaxy. It turns out it may be something even stranger
https://www.skyatnightmagazine.com/news/...ark-matter

INTRO: Astronomers have proposed a radical alternative to the long-held belief that a supermassive black hole sits at the centre of the Milky Way, suggesting that instead a dense clump of dark matter could generate the same gravitational effects. The new study, published in Monthly Notices of the Royal Astronomical Society, argues that an ultra-compact dark matter core can explain both the rapid motions of stars near our galactic centre and the larger-scale rotation of our Galaxy.

For decades, the object known as Sagittarius A* has been interpreted as a black hole more than four million times the mass of the Sun, largely because stars in its vicinity, called S-stars, whirl around
it at enormous speeds. However, an international team have put forward a fermionic dark matter model that could reproduce the same stellar motions without a black hole.

“This is the first time a dark matter model has successfully bridged these vastly different scales and various object orbits, including modern rotation curve and central stars data,” says the study’s co-author Dr Carlos Argüelles. “We are not just replacing the black hole with a dark object; we are proposing that the supermassive central object and the Galaxy’s dark matter halo are two manifestations of the same substance.” (MORE - details)

Eurekalert (excerpts): The international team of researchers have instead put forward an alternative idea – that a specific type of dark matter made up of fermions, or light subatomic particles, can create a unique cosmic structure that also fits with what we know about the Milky Way's core. It would in theory produce a super-dense, compact core surrounded by a vast, diffuse halo, which together would act as a single, unified entity.

The inner core would be so compact and massive that it could mimic the gravitational pull of a black hole and explain the orbits of S-stars that have been observed in previous studies, as well as the orbits of the dust-shrouded objects known as G-sources which also exist nearby.

Of particular importance to the new research is the latest data from the European Space Agency's GAIA DR3 mission, which has meticulously mapped the rotation curve of the Milky Way's outer halo, showing how stars and gas orbit far from the centre.

It observed a slowdown of our galaxy's rotation curve, known as the Keplerian decline, which the researchers say can be explained by their dark matter model's outer halo when combined with the traditional disc and bulge mass components of ordinary matter.

This, they add, strengthens the 'fermionic' model by highlighting a key structural difference. While traditional Cold Dark Matter halos spread out following an extended 'power law' tail, the fermionic model predicts a tighter structure, leading to more compact halo tails.

[...] "Our model not only explains the orbits of stars and the galaxy's rotation but is also consistent with the famous 'black hole shadow' image. The dense dark matter core can mimic the shadow because it bends light so strongly, creating a central darkness surrounded by a bright ring."

The researchers statistically compared their fermionic dark matter model to the traditional black hole model. They found that while current data for the inner stars cannot yet decisively distinguish between the two scenarios, the dark matter model provides a unified framework that explains the galactic centre (central stars and shadow), and the galaxy at large.

The new study paves the way for future observations. [...] The outcome of these findings could potentially reshape our understanding of the fundamental nature of the cosmic behemoth at the heart of the Milky Way. (MORE - missing details, no ads)]]>