Epistemological Role in Science and Synthetic A Priori Knowledge

[dce]

Now I'll be the first to admit I understand, for all practical purposes, close to nothing of theoretical physics. But I came across an article on "phys org" titled "Scientists Glimpse Universe Before Big Bang"(http://www.physorg.com/news/2010-11-scientists-glimpse-universe-big.html). Now from what I do know of physics, a singularity is a point from which our mathematics is not only unable to verify or delve into the realm into the phenomenon, but it is actually proven as an actually mathematically verified impossible task. But I suppose that's based on current scientific understanding, and with new verified knowledge, equations somewhere could be tweaked to yield actual knowledge and then the identifying the phenomenon as a singularity would be flawed. But I'm taking, from my perspective, a huge leap here with not knowing what I'm leaping over. I'll yield this fundamental understanding of mine as flawed and accept the implications of the article prosoped as possible.
After this leap, I accept that this article is suggesting a cyclic universe and that it is within the realm of possibility. But why are the implications that are proposed regarding this effect being suggested as a correlation to a cyclic universe? This article seems to make assumptions that have no epistemological value, however interesting as it may be. Honestly, I, unlike many other "serious" physicists, love the constant barrage of synthetic a priori knowledge, especially prevalent in physics books, proposed as a means of attempting to describe the literally unknowable through science (To many this will seem to many as irrelevant, but I do believe in God). Science seems to be based upon a very strict set of rules and the moment we take science to these unknowable areas of knowledge the topic would seem to not belong within science and venture into what many would call pseudoscience, usually having a negative connotation. But if we jump to this conclusion of a cyclic universe not only would we need to add additional parameters to our knowledge, we would need to, at the very least, make fundamental changes in our interpretation of some very basic knowledge of physics.
So lastly, Calibi-Yau geometry does seem to verify the possibility of 10-dimensional reality through variations of strings. Why would it be such a large step to assume that (from these observations through the article), though space-time seems to be an inherent component of are universe, our reality, including space-time, is within some sort of super-region of unknowable forces? Could this explain explain the effect observed in the article? Now I understand that theoretically it couldn't be predicted at this point, but I want to know where my flaws are in the idea. This is why I have grown so fond of physics it is to me the very essence of art where ideas of reality are adjusted, sometimes with gigantic leaps, to give the individual a new lens every time one of these theories is confirmed. I would really appreciate some feedback though on both the article and the epistemological role in science.

 

[marcus]

Now I'll be the first to admit I understand, for all practical purposes, close to nothing of theoretical physics. But I came across an article on "phys org" titled "Scientists Glimpse Universe Before Big Bang"(http://www.physorg.com/news/2010-11-scientists-glimpse-universe-big.html). Now from what I do know of physics, a singularity is a point from which our mathematics is not only unable to verify or delve into the realm into the phenomenon, but it is actually proven as an actually mathematically verified impossible task...

The cosmological singularity occurs in the context of classical GR. Within that context it can be proven that GR theory has failure points where it blows up/stops giving meaningful numbers.

There is a research area called quantum cosmology where the start of expansion is modeled and the models go back pre-start (or "pre-bang" if you like) and do not blow up.
http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=dk+quantum+cosmology+and+date+%3E2006&FORMAT=WWW&SEQUENCE=
Here are 389 papers in quantum cosmology which Spires says have appeared since the beginning of 2007.

With any model of the past, the crucial thing is to be able to test using what it says we should be able to see in the present. Therefore papers by phenomenologists like these (asserting falsifiability) are important:

http://arxiv.org/abs/1011.1811
Observing the Big Bounce with Tensor Modes in the Cosmic Microwave Background: Phenomenology and Fundamental LQC Parameters
Julien Grain, A. Barrau, T. Cailleteau, J. Mielczarek
12 pages, 5 figures
(Submitted on 8 Nov 2010)
"Cosmological models where the standard Big Bang is replaced by a bounce have been studied for decades. The situation has however dramatically changed in the last years for two reasons. First, because new ways to probe the early Universe have emerged, in particular thanks to the Cosmic Microwave Background (CMB). Second, because some well grounded theories -- especially Loop Quantum Cosmology -- unambiguously predict a bounce, at least for homogeneous models. In this article, we investigate into the details the phenomenological parameters that could be constrained or measured by next-generation B-mode CMB experiments. We point out that an important observational window could be opened. We then show that those constraints can be converted into very meaningful limits on the fundamental Loop Quantum Cosmology (LQC) parameters. This establishes the early universe as an invaluable quantum gravity laboratory."

http://arxiv.org/abs/1007.2396
Constraints on standard and non-standard early Universe models from CMB B-mode polarization
Yin-Zhe Ma, Wen Zhao, Michael L. Brown
(Submitted on 14 Jul 2010)
"We investigate the observational signatures of three models of the early Universe in the B-mode polarization of the Cosmic Microwave Background (CMB) radiation. In addition to the standard single field inflationary model, we also consider the constraints obtainable on the loop quantum cosmology model (from Loop Quantum Gravity) and on cosmic strings, expected to be copiously produced during the latter stages of Brane inflation. We first examine the observational features of the three models, and then use current B-mode polarization data from the BICEP and QUaD experiments to constrain their parameters. We also examine the detectability of the primordial B-mode signal predicted by these models and forecast the parameter constraints achievable with future CMB polarization experiments. We find that:
(a) these three models of the early Universe predict different features in the CMB B-mode polarization power spectrum, which are potentially distinguishable from the CMB experiments;

(b) since B-mode polarization measurements are mostly unaffected by parameter degeneracies, they provide the cleanest probe of these early Universe models;

(c) using the BICEP and QUaD data we obtain the following parameter constraints:
$$r=0.02^{+0.31}_{-0.26}$$ (1 sigma for the tensor-to-scalar ratio in the single field inflationary model);

$$m < 1.36\times 10^{-8} \text{M}_{\text{pl}}$$ and $$k_{*} < 2.43 \times 10^{-4} \text{Mpc}^{-1}$$ (1 sigma for the mass and scale parameters in the loop quantum cosmology model);

$$G\mu < 5.77 \times 10^{-7}$$ (1 sigma for the cosmic string tension);

(d) future CMB observations (both satellite missions and forthcoming sub-orbital experiments) will provide much more rigorous tests of these early Universe models."

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Physicsforums has a PHILOSOPHY FORUM down the menu in the "General Discussion" section. It may be that what you want to talk about belongs there rather than here.

Not all theories of gravity and geometry suffer a singularity at the start of expansion.

There is no epistemological problem with looking back pre-start, more than with any other case of looking back into the past. It always involves assumptions, which one tries to justify, and efforts to test by experiment and observation in the present.

We assume that fairies or aliens did not bury fake dinosaur bones to fool us. We assume that those bones got there the way other bones do---from animals that lived. So we infer that dinosaurs lived. But we cannot know this as a certainty. It involves extrapolation back into the past using a mental model of how things happen in the real world.

The mods may want to move the thread to Philosophy.
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The PhysOrg popularization is AFAICS sketchy and IMO misinformed. I would recommend reading the preprint of Penrose Gurzadyan on Arxiv, instead of the PhysOrg thing.

http://arxiv.org/abs/1011.3706

But Penrose idea is not the leading pre-start cosmology idea. LQC is much more studied. It is one of those mentioned in the papers by phenom'ists Barrau, Grain,...Zhao, and others.

 

[dce]

Awesome man, I really appreciate it.

 

[marcus]

I appreciate your asking the question, dce, and bringing up the Penrose Gurzadyan paper. No one else here has mentioned it so far, I think.
As someone not involved in the research, just an interested bystander, I can't really judge this, but it seems to me that if Penrose and Gurzadyan are right about the existence of concentric circles of suppressed temperature variation----if they are right----then that would tend to discredit the bounce models that come up, for instance, in LQC.

Perhaps P & G are not right and their circles are a statistical mirage---or have some alternative explanation. As a non-expert I cannot think of any, nor can I think of any way such curious patterns (if they exist) in the noisy CMB could arise within the LQC picture.

We'll wait and see as usual Perhaps we'll hear more in the next few months.

 

[bcrowell]

I appreciate your asking the question, dce, and bringing up the Penrose Gurzadyan paper.

There was some discussion here: https://www.physicsforums.com/showthread.php?t=442740

 

[marcus]

Right! Jack brought up the Penrose Gurzadyan paper in post #7 of your thread. Thanks for reminding me.
I hope you agree it merits further discussion, Crowell. But still don't concentric circles in the CMB skymap strike you as a bit odd? Did anyone look up Gurzadyan's previous work?

 

[bcrowell]

But still don't concentric circles in the CMB skymap strike you as a bit odd?

Because...?

Did anyone look up Gurzadyan's previous work?

Gurzadyan got the WMAP and Boomerang collaborations to give him data to look at. He is not part of those collaborations, but he has a ton of papers on CMB on arxiv, seems to be a heavy hitter in the field.

My gut reaction is that if the these features were really believable and robust, then it would be a really momentous discovery, and therefore the big collaborations would jump on it and make a big deal out of it. The fact that they are not co-authors suggests to me that they don't the features are real.

-Ben

 

[marcus]

...My gut reaction is that if the these features were really believable and robust, then it would be a really momentous discovery, and therefore the big collaborations would jump on it and make a big deal out of it. The fact that they are not co-authors suggests to me that they don't the features are real...

This puts it nicely. I was having an uneasy reaction and couldn't say why, it might be that.
If there really were concentric circles then we'd be hearing a lot more about it from several directions.