Universe Expanding: Space or Matter?

[sylas]

I see a bunch of data -- but NOTHING that supports 'acceleration' without using a model for reference. THAT is the point. Further, there are other models that do NOT show acceleration using the same data. So that it seems to me that the model needs to be proved -- somehow -- independent of the data showing these departures -- BEFORE we invent entirely new kinds of energy just to protect a cherished model.

That's just silly. Data is ALWAYS considered in the light of completing models. Without that, it is just numbers. OF COURSE you can't support ANYTHING if you don't actual check data against models. It's okay to be skeptical, but this is just refusing to look.

Your problem is that you weren't even looking at data as far as we could see in your diagram. You evidently have some strong intuitions about what models you are willing to consider, but there's no sign you are willing or able to test those intuitions against data, which is the meat of of how science works.

The models are the lines in the diagrams I provided. I already explained that an empty model does fit this data set tolerably well -- not as well as the dark energy model, but still pretty good. But we BOTH know that this empty model is falsified already. You even said it yourself just above!

You've completely ignored the specific criticism I gave of your comment... you said evidence for dark energy and accelerating expansion only shows up by comparison with the empty universe model. That's flatly false, as I noted previously.

The talk of "proved" is just failing to understand science. We don't "prove" models like theorems. We check them against data. Which is PRECISELY what I am showing in the diagram, and why people were forced into considering dark energy.

The notion of a "cherished" model is more foolishness. In fact, dark energy was a radically surprising idea; not a cherished model at all. Unless, of course, you mean that the new ideas had to preserve "cherished models" like general relativity. Sheesh.

Anyone is welcome to come up with new models that explain the data -- all of it -- better. Nor is that beyond the bounds of possibility. But so far, the evidence points towards dark energy. It's not proved, but it has a credible case, and so far fits the data better than anything else.

Frankly, the concept that matter density -- critical or otherwise -- having much to do with the expansion of the universe is also an question.

A pretty silly one, frankly; this just goes from bad to worse.

----

But back to the general questions of the thread...

Another paper that is worth looking at is Constraints on Dark Energy from Supernovae, Gamma Ray Bursts, Acoustic Oscillations, Nucleosynthesis and Large Scale Structure and the Hubble constant by Ned Wright, at astro-ph/0701584.

It looks at a range of data and models, include data from greater redshifts than really makes empty universe drop out of contention. One of the models considered is an "evolving supernova" model, in which changes in high redshift supernova are taken as changes in the nature of supernovae over time. This proposal has problems also, but its another idea people are considering.

Cheers -- sylas

PS. Added in edit. I wrote this in response to the first edition of your post. Now you seem to be using the data, but thanks all the same... I'll stick with Ned's account of the matter. The substance seen in this thread does not live up to the standard you are trying to claim by virtue of credentials.

 

[Rymer]

The 'cherished' model was not just 'dark energy' -- Dark energy is no more than a 'tack on' to the Standard Model formulation. The Model I'm objecting to is the Standard Model -- and the way General Relativity has been USED to support it.

But what I'm objecting to even more is this tendency I see in cosmology to generate 'bizarre science' to fix a failing model. The current Standard Model is a monstrosity.
It seems to include just about everything someone can attach to it. There is no way to be critical of a part of it without being force to take it on wholesale.

This is NOT the way science should be done. Keep the hypothesis limited to single or at least limited issues -- and check those out. Don't lock down 'the answer' in mathematical 'smoke' in an attempt to confuse the opposition.

I'll say again -- IF the universe is flat -- spatial dimensions not curved, then the
possible options (to me) seem to be:

1) General Relativity is not needed to describe the large scale of the universe.
2) Or we live in an amazing coincidense of a universe that just by 'luck' happens
to be flat. This 'luck' having names like dark matter (exotic) and dark energy.

 

[sylas]

The 'cherished' model was not just 'dark energy' -- Dark energy is no more than a 'tack on' to the Standard Model formulation. The Model I'm objecting to is the Standard Model -- and the way General Relativity has been USED to support it.

But what I'm objecting to even more is this tendency I see in cosmology to generate 'bizarre science' to fix a failing model. The current Standard Model is a monstrosity.
It seems to include just about everything someone can attach to it. There is no way to be critical of a part of it without being force to take it on wholesale.

This is NOT the way science should be done. Keep the hypothesis limited to single or at least limited issues -- and check those out. Don't lock down 'the answer' in mathematical 'smoke' in an attempt to confuse the opposition.

I'll say again -- IF the universe is flat -- spatial dimensions not curved, then the
possible options (to me) seem to be:

1) General Relativity is not needed to describe the large scale of the universe.
2) Or we live in an amazing coincidense of a universe that just by 'luck' happens
to be flat. This 'luck' having names like dark matter (exotic) and dark energy.

Well, I've given some specifics of where your criticisms went from skepticism to outright misrepresentation or misunderstanding of the models.

I also think you are completely incorrect about this being the wrong way to do science; in fact it has been very much the reverse. Cosmology has been progressing and developing and changing precisely because it has become much more an experimental and observation based science. That's going to continue, with new experiments coming up to test the competing ideas. For example, there's the proposed Supernova Acceleration Probe. This will be a strong test of the dark energy hypothesis. If selected, it could be launched next decade.

The idea that science should deliberately limit hypotheses is about as wrong as wrong can be. Dark energy is not sacrosanct. Anyone is welcome to propose and explore new ideas: I mentioned the "evolving supernova" proposal. You can object all you like, but to imagine that you are supporting science by trying to disallow hypotheses based on some intuition you appear to have about what is permissible is so completely counter to how science works that I am actually quite stunned.

By all means take on the current leading models wholesale! Go hard... that's how we develop new insights. But you are going to have to do that with empirical evidence and alternatives that match the data. Not just ruling what you don't like out of bounds, with subjective notions of what you consider "bizarre", or "monstrous", or by just labeling a model you don't like for some reason as "lucky". (What the heck was THAT about?) There's lots about the world which has turned out to be "bizarre" and counter to intuitions. Being open to what seem initially unintuitive is just about a necessary precondition for working in science.

I am pretty certain, frankly, that we are due for some surprises and upsets in physics over the next decade or two, in work on cosmology and fundamental physics. But I expect to progress to come from people who are more willing to go with data, rather than preconceived ideas of what is permissible.

Cheers -- sylas

 

[yogi]

The 'cherished' model was not just 'dark energy' -- Dark energy is no more than a 'tack on' to the Standard Model formulation. The Model I'm objecting to is the Standard Model -- and the way General Relativity has been USED to support it.

But what I'm objecting to even more is this tendency I see in cosmology to generate 'bizarre science' to fix a failing model. The current Standard Model is a monstrosity.
It seems to include just about everything someone can attach to it. There is no way to be critical of a part of it without being force to take it on wholesale.

This is NOT the way science should be done. Keep the hypothesis limited to single or at least limited issues -- and check those out. Don't lock down 'the answer' in mathematical 'smoke' in an attempt to confuse the opposition.

I'll say again -- IF the universe is flat -- spatial dimensions not curved, then the
possible options (to me) seem to be:


1) General Relativity is not needed to describe the large scale of the universe.
2) Or we live in an amazing coincidense of a universe that just by 'luck' happens
to be flat. This 'luck' having names like dark matter (exotic) and dark energy.

Good Post - I have always had doubts about sewing together so many ad hocs to make the model viable - of course, as Feynman suggested, there is no guarantee the universe will turn out to be mathematically beautiful or simple.

But at present the data does not seem to be sufficiently compelling as to justify conclusion

 

[Rymer]

Good Post - I have always had doubts about sewing together so many ad hocs to make the model viable - of course, as Feynman suggested, there is no guarantee the universe will turn out to be mathematically beautiful or simple.

But at present the data does not seem to be sufficiently compelling as to justify conclusion

We are indeed sorely lacking in good data. And it appears that the data we do have are acquired based on the need to support particular a theory. No problem with that per se, but there can be a problem when a single model is 'driving' the interpretation of that data.

The monolithic nature that the Standard Model has become nearly always results in demands for any questioner on a single part that might reflect on the basic model be required to support his idea in so many diverse fields of knowledge that it is impossible for an individual or small group to meet.

Too many people have their entire careers and lives invested in the Standard Model for anything to change in the short term.

Time -- and good data -- will tell.