Slartibartfast wrote:The big bang is built on assumptions and hasn't made testable predictions that have been confirmed like general relativity.
Assumptions: The laws of physics, whatever they may be, are the same everywhere and everywhen.
At large scales, the distribution of matter is the same everywhere.
There is no evidence of a scale at which distribution of matter is uniform. In fact, in all the scales we have observed (sub-atomic, human, solar system, galaxy, galactic cluster and up to galactic filaments) matter is decidedly clumpy. This is a very dubious assumption, in my opinion.
General Relativity is a good summary of the behavior of space, time and gravity. Relativistic Quantum Physics (later the Standard Model of Particle Physics) is a good summary of the behavior of matter and energy.
I would say that they are our best understanding given the current evidence.
From the general behavior of gravity, little fluctuations in density tend to grow over time.
Yes, but for them to grow to 3 gigaparsecs in the time that the universe has existed according to the Big Bang theory there would have had to have been more than "little fluctuations" in the density. Not to mention that, in general, characteristic time scales correlate with size. I'm trying to put together a chart to visualize this, but, intuitively, if a star has a lifespan of billions of years, does it really make sense that the universe, over 18 orders of magnitude larger, should have a lifespan less than one order of magnitude larger? I don't think so.
From the Friedmann equations describing the GR evolution of a homogeneous non-empty space-time without edge, the later universe is cooler and less dense than at times in the past.
I'll accept this as true, but you are making an assumption that the Friedmann equations are a map which accurately describes the territory which I will not accept a priori.
So the Big Bang model is the hypothesis that the observable universe is consistent with the universe once being in such a uniform, hot and dense state that our incomplete human knowledge of the laws of physics is not able to describe it well.
Well stated. Essentially you are saying that the red shift, or the expansion that is inferred from the red shift,
rather, can be extrapolated backwards to a state where our understanding of the laws of physics breaks down, i.e. something we can't, at least not yet, produce in laboratory conditions.
I, on the other hand, will not extrapolate beyond our understanding of the physics. There are other plausible explanations of observations besides the Big Bang and while I'm not necessarily a proponent of any of them, the plasma cosmology, based on the work of Nobel Laureate Hans Alfven is the most intuitively appealing to me. Essentially he suggests that the same plasma phenomena seen in laboratories, the magnetosphere, and the solar system play a significant role in galaxies, interstellar clouds and all the way up to the largest structures in the observable universe.
The gripping hand is just a gratuitous science fiction reference in this case.
At all times in the past, the overwhelming statistical trend will be for matter which is not part of our own gravitationally bound system (galaxy or as it turns out cluster of galaxies) to be retreating from us and this recession caused by the expansion of space should be at first order proportional to distance.
There are some issues with using red shift to measure both distance and velocity as well as alternatives (tired light)
that explain the red shift in other ways. This amounts to an assumption that the Hubble expansion is the correct interpretation of the red shift. Now, I will admit that the Hubble expansion is a very plausible interpretation of the red shift, but it's not the only one.
Hubble's original discovery has been confirmed in detail by repeated studies.
Hubble's discovery, i.e. that (apparent) speed is proportional to (apparent) distance is well-established evidence, yes, but Hubble's explanation for it has not made any predictions that can be verified that I am aware of.
Further that this is General Relativity-predicted cosmological redshift rather than some non-GR light phenomenon is confirmed by the fact that supernovae in remote galaxies are time-dilated consistent with the known behavior of space and time and gravity.
I lack sufficient expertise to argue this, so I will just point out that the validity of the Hubble expansion does not imply the validity of the Big Bang, which, as you said, is an extrapolation far beyond the data.
At at early times until a certain time in the past, the matter in the universe was too hot to remain unionized and thus was plasma and significantly opaque to light at all frequencies (as opposed to atomic and molecular gases which have limited absorption spectra). So all times later than this would be filled with photons emitted by this hot black body. Following the laws of GR, this radiation would cool over time as the universe expanded. This has been confirmed in detail. Today, this is the Cosmic Microwave Background radiation has been shown to be greatly uniform and consistent with a thermal distribution to high degree. Further, for very remote galaxies we can see evidence that it was hotter in the past.
Noterdaeme, P., et al. "The evolution of the cosmic microwave background temperature-measurements of TCMB at high redshift from carbon monoxide excitation." Astronomy & Astrophysics 526
(2011): L7. https://scholar.google.com/scholar?clus ... 0284069603
Not everyone would agree. From a paper by Eric Lerner (a plasma physicist and author of The Big Bang Never Happened).
Recent measurements of the anisotropy of the CBR by the WMAP spacecraft have been claimed to be a major confirmation of the Big Bang theory. Yet on examination these claims of an excellent fit of theory and observation are dubious. First of all, the curve that was fitted to the data had seven adjustable parameters, the majority of which could not be checked by other observations. Fitting a body of data with an arbitrarily large number of free parameters is not difficult and can be done independently of the validity of any underlying theory. Indeed, even with seven free parameters, the fit was not statistically good, with the probability that the curve actually fits the data being under 5%, a rejection at the 2 s level. Significantly ,even with seven freely adjustable parameters, the model greatly overestimated the anisotropy on the largest angular scales. In addition, the Big Bang model's prediction for the angular correlation function did not at all resemble the WMAP data. It is therefore difficult to view this new data set as a confirmation of the Big Bang theory of the CBR.
The plasma alternative views the energy for the CBR as provided by the radiation released by early generations of stars in the course of producing the observed 4He. The energy is thermalized and isotropized by a thicket of dense, magnetically confined plasma filaments that pervade the intergalactic medium. While this model has not been developed to the point of making detailed predictions of the angular spectrum of the CBR anisotropy, it has accurately matched the spectrum of the CBR using the best-quality data set from COBE. This fit, it should be noted, involved only three free pamenters and achieved a probability of 85%.
Since this theory hypotheses filaments that efficiently scatter radiation longer than about 100 microns, it predicts that radiation longer than this from distant sources will be absorbed, or to be more precise scattered, and thus will decrease more rapidly with distance than radiation shorter than 100 microns. Such an absorption was demonstrated by comparing radio and far-infrared radiation from galaxies at various distances--the more distant, the greater the absorption effect[5,7]. This work was done using an IRAS sample limited to flux of more than 5.24mJy at 60 microns. More recent results, reported here for the first time(and to be published in greater detail elsewhere) extend this demonstration of absorption .
If long wavelength radiation is being absorbed or scattered by the intergalactic medium (IGM), then this effect should be constant for all wavelengths longer than about 100-200 microns. Absorption at one wavelength in this range should be the same, for a given galaxy, as absorption at another wavelength. The recent observations of submillmeter, 850micron, wavelengths by the SCUBA survey is an opportunity to test this prediction.
From "A Technical Paper on Plasma Cosmology and Big Bang" at http://bigbangneverhappened.org
With seven parameters you can make an elephant dance the ballet. Just sayin'.
If we posit that at one time it was so hot that unstable free neutrons were likely to be formed by electron-proton collision, then as that cooled only light isotopes should be primordial products of that nucleon sea. Details of how it cooled will be revealed in details of the isotope ratios. The primordial isotopic composition of the universe has been confirmed to be consistent with the understanding of a cooling plasma of protons and neutrons. (There is as yet an unexplained problem with Lithium abundance.)
Gross violation of 4 paragraph rule under sekrit button due to no direct link to the page (really old website design). It is a critique of the light isotope ration predictions of the Big Bang.
The Big Bang model and observation is not consistent with the universe being made up of just protons, neutrons and electrons.
But is the assumption of something in the universe beyond protons, neutrons, and electrons (and radiation, neutrinos, etc.) not multiplying entities beyond necessity? What great need, beyond saving a pet theory, do these completely hypothetical particles serve?
Something else heavy and clumpy like matter is needed if our understanding of the laws of physics is good.
If our understand of the laws of physics are good and the Big Bang is correct, you mean. If we don't assume the validity of the Big Bang, we don't have to explain how something basically homogeneous became unmistakably clumpy.
That hypothetical other matter, dark matter, has been confirmed in the behavior of galactic clusters, spiral galaxy rotation rates with respect to radial distance, gravitational lensing of the bullet cluster and in other ways.
The person who measured the spiral galaxy rotation rates, Vera Rubin, wasn't so sure:
"If I could have my pick, I would like to learn that Newton's laws must be modified in order to correctly describe gravitational interactions at large distances. That's more appealing than a universe filled with a new kind of sub-nuclear particle."[
She felt, later in her life, that we should have found some kind of evidence if dark matter actually existed and, as implied in the quote, leaned towards modified Newtonian dynamics as the leading theory.
Finally, as the Big Bang model is a single hypothesis for all these predictions, the details from multiple lines of otherwise unrelated evidence should be consistent with a single set of parameters. This has been confirmed in detail.
I've pointed the shortcomings of this "fit" out above, but too, also, as a mathematical modeler, I am very wary of top-down models with lots of parameters that aren't based on well-established laws of physics. It is, in my (in this case expert)
opinion, something that should be viewed with much skepticism, especially when theory has gotten out so far ahead of experiment.