Are Astronomers Wrong About Dark Energy? (cnn.com) 30
An anonymous reader shared this report from CNN:
The universe's expansion might not be accelerating but slowing down, a new study suggests. If confirmed, the finding would upend decades of established astronomical assumptions and rewrite our understanding of dark energy, the elusive force that counters the inward pull of gravity in our universe...
Last year, a consortium of hundreds of researchers using data from the Dark Energy Spectroscopic Instrument (DESI) in Arizona, developed the largest ever 3D map of the universe. The observations hinted at the fact that dark energy may be weakening over time, indicating that the universe's rate of expansion could eventually slow. Now, a study published November 6 in the journal Monthly Notices of the Royal Astronomical Society provides further evidence that dark energy might not be pushing on the universe with the same strength it used to. The DESI project's findings last year represented "a major, major paradigm change ... and our result, in some sense, agrees well with that," said Young-Wook Lee, a professor of astrophysics at Yonsei University in South Korea and lead researcher for the new study....
To reach their conclusions, the researchers analyzed a sample of 300 galaxies containing Type 1a supernovas and posited that the dimming of distant exploding stars was not only due to their moving farther away from Earth, but also due to the progenitor star's age... [Study coauthor Junhyuk Son, a doctoral candidate of astronomy at Yonsei University, said] "we found that their luminosity actually depends on the age of the stars that produce them — younger progenitors yield slightly dimmer supernovae, while older ones are brighter." Son said the team has a high statistical confidence — 99.99% — about this age-brightness relation, allowing them to use Type 1a supernovas more accurately than before to assess the universe's expansion... Eventually, if the expansion continues to slow down, the universe could begin to contract, ending in what astronomers imagine may be the opposite of the big bang — the big crunch. "That is certainly a possibility," Lee said. "Even two years ago, the Big Crunch was out of the question. But we need more work to see whether it could actually happen."
The new research proposes a radical revision of accepted knowledge, so, understandably, it is being met with skepticism. "This study rests on a flawed premise," Adam Riess, a professor of physics and astronomy at the Johns Hopkins University and one of the recipients of the 2011 Nobel Prize in physics, said in an email. "It suggests supernovae have aged with the Universe, yet observations show the opposite — today's supernovae occur where young stars form. The same idea was proposed years ago and refuted then, and there appears to be nothing new in this version." Lee, however, said Riess' claim is incorrect. "Even in the present-day Universe, Type Ia supernovae are found just as frequently in old, quiescent elliptical galaxies as in young, star-forming ones — which clearly shows that this comment is mistaken. The so-called paper that 'refuted' our earlier result relied on deeply flawed data with enormous uncertainties," he said, adding that the age-brightness correlation has been independently confirmed by two separate teams in the United States and China... "Extraordinary claims require extraordinary evidence," Dragan Huterer, a professor of physics at the University of Michigan in Ann Arbor, said in an email, noting that he does not feel the new research "rises to the threshold to overturn the currently favored model...."
The new Vera C. Rubin Observatory, which started operating this year, is set to help settle the debate with the early 2026 launch of the Legacy Survey of Space and Time, an ultrawide and ultra-high-definition time-lapse record of the universe made by scanning the entire sky every few nights over 10 years to capture a compilation of asteroids and comets, exploding stars, and distant galaxies as they change.
Last year, a consortium of hundreds of researchers using data from the Dark Energy Spectroscopic Instrument (DESI) in Arizona, developed the largest ever 3D map of the universe. The observations hinted at the fact that dark energy may be weakening over time, indicating that the universe's rate of expansion could eventually slow. Now, a study published November 6 in the journal Monthly Notices of the Royal Astronomical Society provides further evidence that dark energy might not be pushing on the universe with the same strength it used to. The DESI project's findings last year represented "a major, major paradigm change ... and our result, in some sense, agrees well with that," said Young-Wook Lee, a professor of astrophysics at Yonsei University in South Korea and lead researcher for the new study....
To reach their conclusions, the researchers analyzed a sample of 300 galaxies containing Type 1a supernovas and posited that the dimming of distant exploding stars was not only due to their moving farther away from Earth, but also due to the progenitor star's age... [Study coauthor Junhyuk Son, a doctoral candidate of astronomy at Yonsei University, said] "we found that their luminosity actually depends on the age of the stars that produce them — younger progenitors yield slightly dimmer supernovae, while older ones are brighter." Son said the team has a high statistical confidence — 99.99% — about this age-brightness relation, allowing them to use Type 1a supernovas more accurately than before to assess the universe's expansion... Eventually, if the expansion continues to slow down, the universe could begin to contract, ending in what astronomers imagine may be the opposite of the big bang — the big crunch. "That is certainly a possibility," Lee said. "Even two years ago, the Big Crunch was out of the question. But we need more work to see whether it could actually happen."
The new research proposes a radical revision of accepted knowledge, so, understandably, it is being met with skepticism. "This study rests on a flawed premise," Adam Riess, a professor of physics and astronomy at the Johns Hopkins University and one of the recipients of the 2011 Nobel Prize in physics, said in an email. "It suggests supernovae have aged with the Universe, yet observations show the opposite — today's supernovae occur where young stars form. The same idea was proposed years ago and refuted then, and there appears to be nothing new in this version." Lee, however, said Riess' claim is incorrect. "Even in the present-day Universe, Type Ia supernovae are found just as frequently in old, quiescent elliptical galaxies as in young, star-forming ones — which clearly shows that this comment is mistaken. The so-called paper that 'refuted' our earlier result relied on deeply flawed data with enormous uncertainties," he said, adding that the age-brightness correlation has been independently confirmed by two separate teams in the United States and China... "Extraordinary claims require extraordinary evidence," Dragan Huterer, a professor of physics at the University of Michigan in Ann Arbor, said in an email, noting that he does not feel the new research "rises to the threshold to overturn the currently favored model...."
The new Vera C. Rubin Observatory, which started operating this year, is set to help settle the debate with the early 2026 launch of the Legacy Survey of Space and Time, an ultrawide and ultra-high-definition time-lapse record of the universe made by scanning the entire sky every few nights over 10 years to capture a compilation of asteroids and comets, exploding stars, and distant galaxies as they change.
The universe is middle aged (Score:1)
This happens to us all: we get older, our strength starts to fail, and we get slower in general. The energy that let us go so fast in our younger days disappears and we get bulgy around the middle The universe is no exception.
Now get off my lawn.
Re: The universe is middle aged (Score:3)
Dark Energy is to explain an observed effect, so it might be that our perspective is insufficient.
Re: (Score:3)
We are blind men attempting to describe an elephant.
https://en.wikipedia.org/wiki/... [wikipedia.org]
Re: (Score:2)
Re:The universe is middle aged (Score:4, Funny)
Re:The universe is middle aged (Score:5, Funny)
our strength starts to fail
Speak for yourself. When I was younger, I could barely lift $100 worth of groceries. Now, it's easy.
Oh No!!!!!! (Score:2)
Re:Oh No!!!!!! (Score:4, Informative)
In a very real sense, everything in the sky actually *is* falling. Bodies in orbit, stars in galaxies, bodies hurtling between galaxies, they are all "falling"--being pulled by the gravity of other celestial bodies.
Re: Oh No!!!!!! (Score:2)
Science self-corrects (Score:4, Insightful)
When scientists are willing to reconsider long-established scienctific understandings in light of new evidence, that's called good science.
Re:Science self-corrects (Score:4, Interesting)
Yeah, stupid headline. The whole point of the label "Dark Energy" is it's a filler for an unknown that still needs to be explained.
Re: (Score:1)
The whole point of the label "Dark Energy" is it's a filler for an unknown that still needs to be explained.
The whole point of dark energy is to explain why the cosmos is expanding more than it theoretically should be. If it isn't, then you don't need dark energy, or if it isn't expanding as much as formerly believed then you don't need as much of it.
I'm an astronomer who studied supernovae ... (Score:5, Interesting)
... and can say that the question, "how does the luminosity of type Ia supernovae depend on redshift?" is a very, very complex one. The number of factors which come into play is large (metallicity, age of the binary system, extinction in the local environment, extinction in the intergalactic environment, corrections for photometric calibration as a function of redshift, etc.), and it's easy to fall into the trap of finding one correlation that seems to explain everything.
I'll add that it's particularly easy, in my opinion, for theorists to fall into this trap.
Re:I'm an astronomer who studied supernovae ... (Score:4, Funny)
it's easy to fall into the trap of finding one correlation that seems to explain everything.
I'll add that it's particularly easy, in my opinion, for theorists to fall into this trap.
Oh dang, you're right! That's explains everything! ;)
Welcome to the singularity. Again (Score:2)
No. Not that kind of [tech] singularity... The one with infinite density in an infinitesimally small point.
Maybe the second law of thermodynamics won't win after all.
The Sun is fucked (Score:2)
We only have about 1 billion, maybe 2 billion at max years to figure out how to build a generational starship. That may seem like a long time, but it'll be right up on us in no time. You realize that with present day tech, it's basically impossible. We don't have the faintest idea of how to build a habitat in space. It's not even in the realm of imagination as to how to do it. We need to start funding it at a massive level.
Re: (Score:2)
Well, Elmo says we can get 1 Million (or was it 1 Billion) people living on Mars by 2050 as a way to preserve humanity from the Hell he is helping to build on Earth. I'm all for it, starting with him. I vote we give him a hammer, some nails, some wood, etc., strap his ass to one of his rockets, and give him a fair sendoff. Go for it, Elmo, you know you can do it!!
Re: (Score:2)
We only have about 1 billion, maybe 2 billion at max years to figure out how to build a generational starship. That may seem like a long time, but it'll be right up on us in no time. You realize that with present day tech, it's basically impossible. We don't have the faintest idea of how to build a habitat in space. It's not even in the realm of imagination as to how to do it. We need to start funding it at a massive level.
In either case, 1 billion or 2 billion years, we'll either have managed to finish ourselves off, or we'll still be bickering over the imaginary game tokens we've devised to ascribe value of a human being, i.e. money. We refuse to grow up as a species and think in the long-term, because there's a chance we may lose a few game tokens this quarter if we actually start planning for the future.
Are Astronomers Wrong About Dark Energy? Probably (Score:5, Interesting)
Re: (Score:1)
"My feeling is that Dark Matter/Energy will go away when they discover the real explanation, but that's just me."
Brilliant!! You vote to replace the mere placeholders in our theories with something else and then declare the placeholders have gone away. Have you told anyone else about this? Or are we just privileged? Maybe you could write a paper for a physics journal and get back to us in how well it was received. Good luck!!
Read this (Score:2)
https://bigthink.com/starts-wi... [bigthink.com]
This describes the distortion that shows up in headlines like this one that seem to indicate that there is scientific evidence against the consensus, when really such evidence is very weak. Really, read that article.
Is Dark Energy real? Who knows; we don't really understand what's going on.
However, is the supernova evidence that the Universe is accelerating wrong? No. What's more, even if it were, you can come to the conclusion that the Universe is accelerating now with
Subir Sarkar's work ... (Score:2)
Related to the topic at hand ...
I posted this last year when the topic of dark energy and the acceleration of the expansion came up ...
Anyway ...
Watch Subir Sarkar's lecture on Beyond The Cosmological Standard Model [youtube.com].
Sarkar is a professor at Oxford who has done some interesting work providing evidence that the expansion of the universe is NOT accelerating.
Instead, he is saying that there is a dipole effect because earth, and the galaxy cluster that we are in, are all moving in space, and that gives the effec
Re: (Score:2)
Thank you.
Always informative to hear from specialists.
NOT slowing down (Score:3)
The author of this article is confused about what they're saying and makes some incorrect claims about it.
The universe's expansion might not be accelerating but slowing down, a new study suggests.
No, it's still accelerating. They aren't disputing that. They're saying that it's not accelerating as quickly as it used to. It's a higher derivative. There's the size of the universe. Its first derivative is the rate of expansion. That's positive: the universe is expanding. Its second derivative is the rate of acceleration. That's also positive: the rate of expansion is increasing. People have mostly assumed the rate of acceleration was constant (third derivative is zero). These people claim the acceleration is decreasing with time (third derivative is negative).