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Analysis indicates that the universe’s expansion is not accelerating

ras.ac.uk

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Re: Analysis indicates that the universe’s expansion is not accelerating

#151

Post by piker »

ImPostingOnHN wrote: post #65
HeinzStuckeIt wrote: post #20

Earlier quoted context omitted.

As an academic, that is exactly what the kind of noncommittal, don’t burn your bridges with colleagues and funding bodies thing that I would say about even clearly flawed research if I were put on the spot by a popular-press publication. In fact, if you know you can rebut flawed research in time, you might want to assist in hyping it first so that your rebuttal will then make a bigger splash and benefit your personal…

It's also something you could say if you forgot to read the assignment and the professor called on you.

"It makes some profound points, yes. What if? BUT what if not?"

Re: Analysis indicates that the universe’s expansion is not accelerating

#152

Post by xwolfi »

shomp wrote: post #103
ASalazarMX wrote: post #70

Earlier quoted context omitted.

> In general, if conservation laws are to hold, expansion must be balanced with [eventual] contraction, is that not obvious? Why would this be? The only physics we know is the one inside our observable universe, there could be variations beyond, or even unknowable laws that don't require conservation of matter outside the edge of the universe. Our incredibly vast universe could be a minuscule blob feeding from an inc…

Because energy cannot be created nor destroyed

Evidently energy was created, or it would not exist, would it ? It probably can be destroyed back to the pre-energy state in some way, just not on a scale we comprehend or even care about.

I suppose we're like bubbles on a boiling pot of water when the fire stops: all this agitation spreads out on the entire volume, and sure no energy was lost, but there are so little bubbles and so much water, once the heat has spread out entirely, the whole volume of water looks pretty dead.

Re: Analysis indicates that the universe’s expansion is not accelerating

#153

Post by jiggawatts »

alfiedotwtf wrote: post #146
jiggawatts wrote: post #137

Earlier quoted context omitted.

The idea is that standard candles are based on chemistry and microscopic physics only, not cosmology.

If I remember correctly (sorry it’s been a while), the size of the star determines its colour, and the data suggests that the colour of stars fits nicely into the mass of a star (ie you’ll never see a star of X color thats Y kg)

The rule is violated in all sorts of fun and interesting ways. There's white dwarfs, for one, then stars with varying levels of metallicity. Stars can merge, which does strange things to their position on the Hertzsprung–Russell diagram. There's oddball combinations like a red giant with a neutron star that has sunk into its core, called a Thorne–Żytkow Object!

Not to mention variable stars, novae, occultation by dust clouds, etc.

Re: Analysis indicates that the universe’s expansion is not accelerating

#154

Post by mr_mitm »

JumpCrisscross wrote: post #140
negativelambda wrote: post #116

Earlier quoted context omitted.

I know the team that did this. In fact i was listening to their seminar just a few days ago. They are very careful and have been working on this a long time. One caveat that they readily admit is that the sample used to create the luminosity age relation has some biases such as galaxy type and relatively lower redshift. They will be updating their results with the Rubin LSST data in the next few years. Exciting times…

> after decades of a standard LCDM model Could you help me understand this sentence: "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”?

The CDM model has no dark energy, unlike the LCDM model. The L stands for Lambda, which is the dark energy term in the Einstein equations. So they are saying when accounting for this effect, our universe looks more like a universe without dark energy, at least when only considering the supernovae probe.

Re: Analysis indicates that the universe’s expansion is not accelerating

#155

Post by mr_mitm »

HeinzStuckeIt wrote: post #20
jampekka wrote: post #17

Earlier quoted context omitted.

At least The Guardian has a comment from an independent expert: "Prof Carlos Frenk, a cosmologist at the University of Durham, who was not involved in the latest work, said the findings were worthy of attention. “It’s definitely interesting. It’s very provocative. It may well be wrong,” he said. “It’s not something that you can dismiss. They’ve put out a paper with tantalising results with very profound conclusions.”…

As an academic, that is exactly what the kind of noncommittal, don’t burn your bridges with colleagues and funding bodies thing that I would say about even clearly flawed research if I were put on the spot by a popular-press publication. In fact, if you know you can rebut flawed research in time, you might want to assist in hyping it first so that your rebuttal will then make a bigger splash and benefit your personal…

I read it as "I recognize some of the names and the abstract doesn't sound like complete nonsense".

Re: Analysis indicates that the universe’s expansion is not accelerating

#156

Post by mr_mitm »

andrewflnr wrote: post #127

> 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 de…

The CMB and BAO measurements give us a picture of how the early universe looked. Supernovae are sensitive to the conditions in the late universe. All probes, which are mostly independent, always pointed at the same amount of dark energy.

Now these people are saying SN actually point at zero dark energy, if accounting for the physics properly. That doesn't invalidate the CMB and BAO results. So dark energy must have had a big influence in the early universe, and no influence in the late universe, so it must by dynamic. (Ironically, supernovae were the first evidence for dark energy, which I guess was just a coincidence, if this new research is correct.)

Re: Analysis indicates that the universe’s expansion is not accelerating

#157

Post by mr_mitm »

shomp wrote: post #51

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?

Maybe this helps: https://www.preposterousuniverse.com/blog/2010/02/22/energy-...

My favorite quote:

> I like to think that, if I were not a professional cosmologist, I would still find it hard to believe that hundreds of cosmologists around the world have latched on to an idea that violates a bedrock principle of physics, simply because they “forgot” it. If the idea of dark energy were in conflict with some other much more fundamental principle, I suspect the theory would be a lot less popular.

Re: Analysis indicates that the universe’s expansion is not accelerating

#158

Post by aatd86 »

antonvs wrote: post #40
aatd86 wrote: post #29

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…

> After all, existence in itself is irrefutable and cannot not exist by definition. I can say the same about forgnoz, which is something I've just invented that must exist by definition. You'd need to try a bit harder to make existence actually inevitable.

You have a material view of existence perhaps. How would the notion of nothingness even exist if there was no existence in the first place? And if we even accepted that nothing was possible, which in itself doesn't make any sense, how would something even start to exist? Well the contradiction is already in the fact that there is a preexisting concept of nothing in the first place. Existence is impredicative too. It defines itself. That's a fact.

It is not because it is impredicative that it needs to be hard to understand I think. It's almost a tautology rather.

Oh by the way, forgniz exist, you made it to design something. It doesn't have to refer to something material. It could be an idea. After all, inventions don't exist by being material in the first place. But idea have at least material support (your brain signals) and the data acquired through your body. As far as we know.

Re: Analysis indicates that the universe’s expansion is not accelerating

#159

Post by aatd86 »

antonvs wrote: post #99
gcanyon wrote: post #87

Earlier quoted context omitted.

I think they mean existence in general, not the existence of any specific thing. Meaning that if there were no “existence” then we wouldn’t be here to consider its nonexistence.

> I think they mean existence in general, not the existence of any specific thing. Yes, but the definition of "existence" doesn't require that anything must actually exist. In other words, it is not the case that existence "cannot not exist by definition." > Meaning that if there were no “existence” then we wouldn’t be here to consider its nonexistence. That's an anthropic principle argument, which is not an argument…

Yes but then there is always something that must exist which is the concept of absence of existence. So it doesn't make sense.

Re: Analysis indicates that the universe’s expansion is not accelerating

#160

Post by aatd86 »

pinkmuffinere wrote: post #75
antonvs wrote: post #40

Earlier quoted context omitted.

> After all, existence in itself is irrefutable and cannot not exist by definition. I can say the same about forgnoz, which is something I've just invented that must exist by definition. You'd need to try a bit harder to make existence actually inevitable.

You’re being downvoted, but your point is true — something can exist “by definition”, and yet not exist in our real world. The thing that exists “by definition” is just a version that we have imagined to exist by definition. But imagining something with property X doesn’t imply anything can actually be found with property X. Side-note: the deontological argument is an argument for the existence of God, which uses the…

Nope :) It 's not about that. It's not because I imagine that there is a banana in front of me that there will be. It's not tied to material existence in that way. It's perhaps another notion of existence which should be more mathematical.

You could think it as "God" provably existing as an idea but that might or might not be realized probabilistically, in our material world. The idea exists obviously. Same as "Zeus"... or "Batman" any other such notions. "Existence" being different from "alive" as we colloquially understand it.

The point is absence of anything is still something. The idea of nothing can only exist if there is existence first. How does it make sense? Then nothing can't exist. Not as an absolute. It can only be a relative negative within a weirdly heterogeneous infinity.

Or you could see it as a predicate, sometimes false, sometimes true. It forms a lower universe of types than existence which is the set of all predicates. Predicates just...exists. They don't have to return true all the time.

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