Arthur T Knackerbracket has found the following story:
The accelerating expansion of the Universe may not be real, but could just be an apparent effect, according to new research published in the journal Monthly Notices of the Royal Astronomical Society. The new study—by a group at the University of Canterbury in Christchurch, New Zealand—finds the fit of Type Ia supernovae to a model universe with no dark energy to be very slightly better than the fit to the standard dark energy model.
Dark energy is usually assumed to form roughly 70% of the present material content of the Universe. However, this mysterious quantity is essentially a place-holder for unknown physics.
Current models of the Universe require this dark energy term to explain the observed acceleration in the rate at which the Universe is expanding. Scientists base this conclusion on measurements of the distances to supernova explosions in distant galaxies, which appear to be farther away than they should be if the Universe's expansion were not accelerating.
However, just how statistically significant this signature of cosmic acceleration is has been hotly debated in the past year. The previous debate pitted the standard Lambda Cold Dark Matter (ΛCDM) cosmology against an empty universe whose expansion neither accelerates nor decelerates. Both of these models though assume a simplified 100 year old cosmic expansion law -- Friedmann's equation.
Reference: Lawrence H. Dam, Asta Heinesen, David L. Wiltshire. Apparent cosmic acceleration from Type Ia supernovae. Monthly Notices of the Royal Astronomical Society, 2017; 472 (1): 835 DOI: 10.1093/mnras/stx1858
-- submitted from IRC
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(Score: 2) by The Mighty Buzzard on Sunday September 17 2017, @08:49PM
Good job. I knew you'd figure that one out. I was going to put a fix in for it earlier but I decided to change the oil in my car and have a nap instead.
My rights don't end where your fear begins.
(Score: 2) by The Mighty Buzzard on Sunday September 17 2017, @08:54PM
Also, thanks for finding another bug. This one's in the filter execution itself, so double kudos.
My rights don't end where your fear begins.
(Score: 2) by The Mighty Buzzard on Sunday September 17 2017, @10:36PM (2 children)
Much better.
!=
My rights don't end where your fear begins.
(Score: 4, Funny) by Azuma Hazuki on Sunday September 17 2017, @11:30PM (1 child)
That's what SHE sed!
I am "that girl" your mother warned you about...
(Score: 0) by Anonymous Coward on Monday September 18 2017, @01:25AM
What she sed is AWKward.
(Score: 3, Informative) by Anonymous Coward on Sunday September 17 2017, @05:57PM
Please always include the free and open arxiv link [arxiv.org] when discussing an otherwise paywalled article.
(Score: -1, Troll) by Anonymous Coward on Sunday September 17 2017, @06:08PM (1 child)
..., is totally irrelevant to anything. If cosmology is going to full on adopt this method of "analysis", get ready for the equivalent of "coffee/fat/carbs is good for you, wait we meant bad."
(Score: 1, Interesting) by Anonymous Coward on Sunday September 17 2017, @07:07PM
Not a troll... They tested the hypothesis that we live in "an empty universe whose expansion neither accelerates nor decelerates". In the process assuming "an expansion identical to that of a featureless soup, with no complicating structure."
So, definitely not our universe. When they found the data (from our universe) was inconsistent with what was predicted for the "not our universe", it was claimed that some huge percentage of our universe was made of "dark energy".
The new idea here is that : "the present Universe actually contains a complex cosmic web of galaxy clusters in sheets and filaments that surround and thread vast empty voids."
Good, keep making the models more realistic, but stop claiming you've discovered something about our universe just because you observe a deviation from your simplified model.
(Score: 2, Insightful) by Anonymous Coward on Sunday September 17 2017, @08:08PM (5 children)
"Dark energy is usually assumed to form roughly 70% of the present material content of the Universe. However, this mysterious quantity is essentially a place-holder for unknown physics."
Bingo. Dark Matter/Energy might as well be invisible rainbow ponies or empty flying spaghetti bowls.
Helluva way to say, "We've no clue, so we made this up."
(Score: 2) by Gaaark on Monday September 18 2017, @02:00AM
Insightfully insightful!
Glad they are finally admitting it.
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 0) by Anonymous Coward on Monday September 18 2017, @03:15AM
Yes. The "unknown physics" could even be a rather boring artifact of their data analysis method. The light-curve fitting that is necessary to derive supernova intensity is only thinly justified. It wouldn't be surprising if the dark energy signal is really due to ancient novae acting differently from recent ones.
(Score: 2) by PiMuNu on Monday September 18 2017, @09:56AM (1 child)
> "However, this mysterious quantity is essentially a place-holder for unknown physics"
> ...
> Helluva way to say, "We've no clue, so we made this up."
I agree with this statement; but only in the context that ALL of physics is "made up"; we choose the best model for the data, which is still Dark Energy (and Dark Matter).
I think you are using the wrong emphasis on things. In physics, we make a model that best fits the available data. The accelerating universe model best fits the available data on the cosmological scale. On the microscopic scale, we have no available interpretation for dark energy; but we can't probe scales appropriate to make any useful statement about anything to do with gravity. Put another way, gravity is such a weak force that we have no way to measure it in particle colliders.
(Score: 1) by khallow on Monday September 18 2017, @12:04PM
And the stretching of space-time due to alleged dark energy is many orders of magnitude smaller than gravity. I seem to recall 120 orders of magnitude is claimed.
(Score: 1, Insightful) by Anonymous Coward on Monday September 18 2017, @04:36PM
Dark matter could be invisible rainbow ponies, but invisible elementary particles are the by far simpler theory, and therefore preferable (indeed, the existence of invisible rainbow ponies would imply the existence of invisible elementary particles, as that would be what invisible rainbow ponies would have to be made of).
Empty flying spaghetti bowls are out of the question as those would consist of baryonic matter, and thus would be visible, especially given that there is much more dark matter than ordinary matter.
Neither invisible rainbow ponies nor empty flying spaghetti bowls would have the right properties to explain dark energy.
(Score: 3, Informative) by PiMuNu on Monday September 18 2017, @09:41AM
See also:
https://en.wikipedia.org/wiki/Dark_energy#Evidence_of_existence [wikipedia.org]
(Score: 2) by Grishnakh on Monday September 18 2017, @03:01PM (1 child)
I wonder what the reason is for making it look like the universe is expanding, and that expansion is accelerating. After all, the universe isn't even real; it's just a big simulation that we're living in. That's why we have fundamental limits like the Planck length: these are the resolution limits of the simulation.
(Score: 1, Interesting) by Anonymous Coward on Monday September 18 2017, @04:23PM
Without an expanding universe, you'd have no dark night sky. [wikipedia.org] But without a dark night sky, no life on earth would be possible. So if there are universes with all sorts of parameters (as you might expect if someone is exploring the evolution of universes through simulations), then only those with expanding universes will enable life.
Why the expansion has to be accelerating? Maybe because that way there's no way new galaxies will ever show up at the cosmic horizon. Basically it means that you are assured that the future of your simulation is completely determined by the part of the universe you simulate, without the need to make up new galaxies on the fly. Indeed, as time goes on (and thus the structures you have to simulate get more complicated), in an universe with accelerated expansion the amount of matter you need to simulate goes down, as galaxies pass to beyond the cosmic horizon. Unlike with a decelerating expansion, where galaxies which previously have been beyond it will show up at the cosmic horizon.