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This article from Creation Magazine argues that:

If the big bang were true, the light from the fireball should cast shadows in the foreground of all galaxy clusters.

It uses some 2006 findings about Cosmic Microwave Background radiation to argue that there are flaws in the Big Bang Theory.

The page links to a related article which says:

NASA announced, with fanfare, how they were looking right back into the beginning of the universe. But the lack of the right shadows shows that CMB cannot be from the big bang at all. Thus what had been touted as one of the main glorious predictions of the big bang is falsified. If the CMB has nothing to do with the big bang, then the COBE fluctuations are irrelevant.

Is there any truth in the claims made in both of these articles?

Shadows will be cast when a body is in front of a source of light. So if the Big Bang produced the most amount of light, why isn't this light cast on everything.

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    This seems like a gross misunderstanding of the Big Bang. firstly, it wasn't a fireball, it's a rapid expansion of space itself. Second, why would galaxies cast shadows from the Big Bang when they're created by it? It's like suggesting that the flames in a fire should cast shadows from the flames behind them. – BorderlineBaguette Jun 8 '16 at 10:14
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    @BorderlineBaguette I don't think creationists have ever been worried about misunderstanding (or misquoting) any science. I suppose we could ask them for the calculations that predict a shadow. I won't hold my breath though. – hdhondt Jun 8 '16 at 10:45
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    @BorderlineBaguette The photons observed near Earth as the cosmic microwave background (according to mainstream theory) have been traveling since recombination (about 379,000 years after the big bang) and therefore originate from a very distant periphery (otherwise they would have arrived long ago). The distant periphery must be beyond the observed galaxy clusters. The light encounters these clusters and interacts. – DavePhD Jun 8 '16 at 12:00
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    @hdhondt, flames can in fact cast shadows: youtube.com/watch?v=Xnk6RoaOKM4&t=24s – Ray Butterworth Nov 17 at 15:42
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    "Gross misunderstanding of basic concepts" is pretty much how most of creationism and intelligent design arguments work. As a rule they rely on their target audience also not understanding those concepts. – Shadur Nov 18 at 8:07
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The quote in the OP from the creation article is an accurate summary of a mainstream Science Daily article: Big Bang's Afterglow Fails Intergalactic 'Shadow' Test:

If the standard Big Bang theory of the universe is accurate and the background microwave radiation came to Earth from the furthest edges of the universe, then massive X-ray emitting clusters of galaxies nearest our own Milky Way galaxy should all cast shadows on the microwave background.

enter image description here

In turn, the Science Daily article is based mainly upon:

The Sunyaev-Zel'dovich effect in a sample of 31 clusters: A comparison between the X-ray predicted and WMAP observed decrement, Astrophysical Journal, Vol. 648, p. 176-199. (alternative link to pre-prints)

One vital test of the present cosmological paradigm is the search for scattering of the CMB by foreground structures such as clusters of galaxies. Such observations can provide important information both about clusters of galaxies as well as basic cosmological parameters like Ho. For the CMB, scattering arises from the Compton interaction with free electrons in the hot (X-ray temperature) plasma of clusters of galaxies, which removes Rayleigh-Jeans blackbody flux in the direction of a cluster, and leads to an apparent decrease in the CMB temperature, a phenomenon known as the Sunyaev-Zel’dovich effect (SZE). By now, the degree of SZE is highly predictable for many clusters of galaxies, because their hot intracluster medium (ICM) properties are well-measured by X-ray satellite missions.

...

In summary, it is through the first detailed radial profile comparison between X-ray and microwave observations that an apparent sample-wide discrepancy between the expected and measured levels of SZE from some of the best known clusters of galaxies was uncovered

See also Detailed X-ray/WMAP comparison for a sample of 31 nearby galaxy clusters - incomplete Sunyaev-Zel'dovich silhouette and the question of the CMB distance scale the abstract of which says:

A resolution of this discrepancy between predicted and observed decrements have potentially extreme ramifications for our interpretation of the CMB. One is forced to conclude that either the CMB is non-cosmological, or there are issues with the WMAP data itself which must be taken into account when interpreting the CMB emission.

See also the Phys.org article Big Bang's Afterglow Fails an Intergalactic Shadow Test:

The apparent absence of shadows where shadows were expected to be is raising new questions about the faint glow of microwave radiation once hailed as proof that the universe was created by a "Big Bang."

which offers another popular science summary.

Both the creation article and the Science Daily article quote Dr. Lieu as saying:

Either it (the microwave background) isn’t coming from behind the clusters, which means the Big Bang is blown away, or … there is something else going on

The title in the OP isn't representative of this "either ... or" statement.

In other words, there are alternative explanations, no one quoted in the OP is saying that the research "disproves" the big bang theory.

Dr. Lieu's publication was from 2006. Looking at articles citing to Dr. Lieu's is the best way to see the current status of this research. The big bang theory is not considered disproven.

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    Follow-ups to this test show that these results can, in fact, be consistent with the Big Bang: mnras.oxfordjournals.org/content/402/2/1179.full.pdf – called2voyage Jun 8 '16 at 15:09
  • A short summary would be help. Am I right in concluding from your answer that (a) yes, the predicted "shadows" are indeed missing, which proved to be a challenge to some models of the Big Bang, but [via the comment which probably deserves a place in the answer] (b) there are tweaks to the model parameters that can explain this anomaly, so underlying theory remains intact with small improvements to the models? – Oddthinking Jun 9 '16 at 2:28
  • So the deficit was document in around 2005/2006, the model was improved around 2009, and the Creationist article was written in 2015. – Oddthinking Jun 9 '16 at 2:31
  • @Oddthinking so basically you are saying the creationist have a point? since they waited until after? – Lucian09474 Jun 9 '16 at 2:33
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    @Lucian09474: I'm not sure if that was tongue-in-cheek, but just in case: No, I am saying the creationist was criticising an out-dated model, and wasn't up-to-date with the latest science. (Which is an easy trap to fall into.) – Oddthinking Jun 9 '16 at 2:43
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The Big Bang was the whole universe. There was no "centre" to the Big Bang; the (hypothetical) point source was all of the universe. There was no space expanding from that point, space itself was expanding.

Hence light from the BB was everywhere in the whole universe. If you were there it would be like living in the middle of a massive fireball - so there cannot be any shadows in any direction. You could not be at the "edge" of that fireball, everything was in the middle of it. And, until 380,000 years after the BB, photons were not free to travel, as the universe was not even transparent to light.

At the time of the CMB, 380,000 years after the BB, the temperature of the universe was about 3,000K, roughly the melting temperature of Tungsten, or double the melting point of Iron. At that temperature, electrons and nucleons could just combine into atoms, and, as it was no longer a plasma, the universe became transparent to radiation. But to this question it does not really matter what the temperature was, as everything was at the same temperature, accurate within about 1 part in 10,000, as reflected in the anisotropy of the BB.

EDIT

The effect mentioned in the OP comes from a study in 2006 by Dr Lieu of the University of Alabama. It relates to the fact that, although the CMB comes from everywhere, in the direction of glacatic clusters we should see a reduction in the glow. This is caused by ionised gases in the cluster distorting the CMB and is called the Sunyaev–Zel’dovich effect (SZE). Dr Lieu found that the signal from the direction of clusters did not match the predicted SZE. However, in 2009 Diego and Partridge used more data from the WMAP probe and found that, while there are still some discrepancies, they depend strongly on the particular model used, and they can accommodate the measurements. They concluded:

the combination of a steeper gas profile and the contribution from point sources allows us to consistently explain the X-ray emission and SZE in galaxy clusters as measured by both ROSAT and WMAP.

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    @Sklivvz It's not a good answer, because the light arriving at Earth now, having traveled uninterrupted since 380,000 years after the big bang, is necessarily from a distant spherical shell, a distant 'edge' so to speak, and would cast a shadow. – DavePhD Jun 8 '16 at 12:17
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    @DavePhD It doesn't work that way at all. The large majority of observable space does not have anything in it, as far as we can tell. This is where we see CMB. The rest are tiny dots we call stars/galaxies/nebulae etc. which obviously block CMB which is a background radiation. That said, the radiation distribution itself doesn't seem to have "halos" around stars. See also: pic of this, Wikipedia – Sklivvz Jun 8 '16 at 13:46
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    @Sklivvz It seems like you're just repeating my comment. We're both saying that galaxy clusters (where they exist) block the CMB radiation. We're both contradicting the part of the answer that says "there cannot be any shadows in any direction". – DavePhD Jun 8 '16 at 14:05
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    Nope, there cannot be (and there aren't) any "shadows" in the background radiation. There are only items in the foreground. The answer refers to the period before there were any items and explicitly says there cannot be anything outside the big bang. What you refer to is inside. It's tricky, but the answer is correct -- just hard to interpret. – Sklivvz Jun 8 '16 at 14:22
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    @Sklivvz Science Daily words it as "cast shadows on the microwave background", but I would word it as "galaxies cast shadows on the Earth with respect to the microwave background" or "galaxies block the path of microwaves to Earth from distant points beyond". – DavePhD Jun 8 '16 at 14:30

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