by JumpCrisscross
2 subcomments
- “Supernova (SN) cosmology is based on the key assumption that the luminosity standardization process of Type Ia SNe remains invariant with progenitor age. However, direct and extensive age measurements of SN host galaxies reveal a significant (5.5σ) correlation between standardized SN magnitude and progenitor age, which is expected to introduce a serious systematic bias with redshift in SN cosmology. This systematic bias is largely uncorrected by the commonly used mass-step correction, as progenitor age and host galaxy mass evolve very differently with redshift. After correcting for this age bias as a function of redshift, the SN data set aligns more closely with the cold dark matter (CDM) model” [1].
[1] https://academic.oup.com/mnras/article/544/1/975/8281988?log...
- > type Ia supernovae, long regarded as the universe’s "standard candles", are in fact strongly affected by the age of their progenitor stars.
A key point in the article. From what I understand, this is the main way we measure things of vast distance and, from that, determine the universe's rate of expansion. If our understanding of these supernovae is wrong, as this paper claims, that would be a massive scientific breakthrough.
I'm really interested in the counterargument to this.
- Seems like the problem should be pretty easy to figure out. Just need to wait ~5 gigayears and see which model is right. I'm personally hoping for deceleration so that we have more total visitable volume.
I'll set a reminder to check back at that time to see who was right.
- Anyone know how credible this is? If true, then that means the big bounce is back on the menu, and the universe could actually be an infinitely oscillating system.
by cosmicjoe
3 subcomments
- As a non-scientist I've always found the Cosmic Distance Ladder as likely to be inaccurate due its assumption about the constant brightness of Standard Candle stars over their lifetime, and the compounding of error at each rung of the ladder. Direct measurement of the CMB seems to be simpler with less chance of error.
https://en.wikipedia.org/wiki/Cosmic_distance_ladder
- If they are replacing a fixed cosmological constant by a model with variable dark energy, doesn't it introduce extra parameters that describe the evolution of dark energy over time? If so, wouldn't it lead to overfitting? Can overfitting alone explain better match of the new model to the data?
- I would not be surprised if the universe was somewhat elastic, expands and then contracts and then expands ad infinitam.
After all, existence in itself is irrefutable and cannot not exist by definition.
If we subscribe to a theory of the multiverse, set theory, likelihood, and interaction driven evolution based on gradient type of fundamental laws.
Locally changing. Obviously everything sharing a fundamental quality that is part of existence itself. But obviously there are sets, there is differentiation. But it is not created, the infinity of unconstrained possibilities exists in the first place and reorganizes itself a bit like people are attracted to people who share some commonalities or have something they need from each other and form tribes. Same processus kind of works for synapse connections, works for molecule formations, works for atoms... etc...
Everything is mostly interacting data.
We could say that the concept of distance is a concept of likelihood. The closer is also the most likely.
Just a little weird idea. I need to think a bit more about it. Somewhat metaphysic?
- If you cover up the part of the Figure 3 graph past "now", it kind of fits a sine wave. https://ras.ac.uk/sites/default/files/2025-10/Figure%203.jpg
Universe gong.
by andrewflnr
1 subcomments
- > The corrected supernova data and the BAO+CMB-only results both indicate that dark energy weakens and evolves significantly with time.
> More importantly, when the corrected supernova data were combined with BAO and CMB results, the standard ΛCDM model was ruled out with overwhelming significance, the researchers said.
I notice they're not saying that dark energy is entirely unnecessary. Do we know if that's just default caution, or are there still strong reasons to believe dark energy exists?
- Was there a date at the top of this? I didn't see one. I saw a similar headlines earlier this year and I'm trying to understand that this is something new
by denismenace
1 subcomments
- Did it change during our life time?
by candiddevmike
4 subcomments
- Aside from unanswerable questions (has the universe started to fill it's container? Is a simulation property nearing "1"?), does this make long distance space travel feasible again? I thought there was something around the universe is expanding too fast to visit places like Alpha Centuri (and preventing visitors to us).
- Standard candles (all these measurements of redshift according to distance, need us to actually get the distance of what we are measuring right) are the gift that keeps on giving.
This study (and many others, depending on the cosmic scales they use) mainly use Supernovas of Type Ia. I.e. the energy emitted by the supernova of a binary acreccion star, which is a star that is capturing the mass from another start that is very nearby and increasing its mass until it collapses into itself, increases temperature up to the point it starts fusing helium, and goes supernova with all the added energy.
That was (and still is now, with some corrections we found since middle last century) supposed to be the same everywhere. Problem is, we keep finding new corrections to it - like this study claims.
That is in fact the big claim of this study (ignore the universe expansion part), that they found a new correction to the Supernova of type Ia luminosity. It's a very big claim and extremely interesting if confirmed. But, like all big claims, it needs a big confirmation. I'm a bit skeptic TBH.
by WalterBright
0 subcomment
- I picked the wrong week to put my faith in cosmology!
- Someone dumped a flat panel near a noisy planet.
by kittikitti
0 subcomment
- This is a fascinating discovery! It's brings into focus the Deep Field imagery from the JWST and how gravitational lensing was found to be greater than expected along with galaxies that were much older than expected based on redshift calculations. Perhaps this could indicate that the universe is even older than we originally thought if redshift calculations accounted for an incorrect perpetual acceleration.
- Circular universe...?
big bang -> expands -> expansion slows -> starts retracting -> singularity again -> big bang again
Roger Penrose seems to be leaning/more convinced of the circular universe theory....
- What does 'now' mean here?
by johnwheeler
0 subcomment
- Just because infinity is a hard thing to understand doesn't mean the universe is and has always been infinite.
by socrateswasone
0 subcomment
- [dead]
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by samdoesnothing
0 subcomment
- Thanks, AI.
by mrbluecoat
5 subcomments
- I have a great deal of respect for the sciences but sometimes astronomy just feels like one giant guessing game: age of the universe, big bang starting as a joke and all the "first minute" timelines thereafter, dark energy and dark matter (code for we have no idea what it is) vastly outnumbering everything else, and now questioning the Nobel Prize-awarded universe expansion. Meanwhile, asteroids the size of buses+ keep whizzing by closer than the moon with little or no warning. Sigh.
- We need an index tracking the expansion rate . And an ETF on it
by CommenterPerson
0 subcomment
- Maybe someone is tailgating it. And it's trying to annoy them by speeding up, then slowing down.
There seem to be so many fudge factors in the whole chain of analysis we won't have an idea until we can make vastly improved measurements.
- Mainstream physics has been delighted to ignore/abandon essential conservation laws when talking about the expanding universe. It's kinda weird, I tried publishing a paper on it recently and it was not received well. In general, if conservation laws are to hold, expansion must be balanced with [eventual] contraction, is that not obvious? Apparently it was quite contentious to say until... this article?
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