Astronomers see the 1st stars dispel darkness 13 billion years ago at 'Cosmic Dawn

[Admin]

The CLASS telescope array has taken a fresh look at the infant universe to hunt for polarized light in the Cosmic Microwave Background that resembles light bouncing off a cosmic car hood.

Astronomers see the 1st stars dispel darkness 13 billion years ago at 'Cosmic Dawn : Read more

 

[Unclear Engineer]

This article is a mess!

It states:
"Suddenly, photons were free to travel unimpeded through the cosmos as the universe instantly went from transparent to opaque. This "first light" is seen today as the CMB."

With statements like that, the article loses all credibility. Please note that the definition of "opaque" is :
"1. Blocking the passage of radiant energy and especially light" https://www.merriam-webster.com/dictionary/opaque

Then it says:
"When the first stars formed, their intense radiation ripped electrons from neutral hydrogen once again, an event called "reionization," turning the universe dark again during an epoch known as the 'Cosmic Dark Ages."'

But, that would mean that we are still in the "cosmic dark ages", even now with the hydrogen ionized, still. So, why could we seen anything by a white haze? Oh, maybe because the authors think "opaque" means "transparent"?!

So, what seems to be "opaque" is these continuing misstatements about how light behaved in the universe between 380,000 years after the "Big Bang" and the "cosmic dawn" when it is thought that stars began emitting light.

Trying to get something intelligent out of the article, it seems that the CLASS radiotelescopes are looking for polarized microwaves amid the CMBR.

But, the article's statements:
" What this team specifically aims to measure with CLASS is the probability of a photon from the CMB encountering an electron ripped free of neutral hydrogen by the universe's first stars and being scattered."

However, there is no explanation of how such a random scattering process would occur in such a manner to cause an observable degree of polarization here on Earth from stars well over 13 billion light years away.

Statements like:
""Using the new common signal, we can determine how much of what we're seeing is cosmic glare from light bouncing off the hood of the Cosmic Dawn, so to speak."

This seems to portray "the Cosmic Dawn" as some sort of wall with conductive properties that would polarize reflecting light, like the automobile hood used as an analogy in the article.

But, that analogy does not seem to fit a theory where there is no "wall" at all, just light going everywhere at all angles from a phase change over an entire volume, which is the CMBR, and maybe along with that, unpolarized light being emitted from the first stars.

So, please provide a cogent scientific explanation of how this theorized polarization of just the starlight and not the CMBR is conceptualized to have occurred.

 

[contrarian]

It states:
"Suddenly, photons were free to travel unimpeded through the cosmos as the universe instantly went from transparent to opaque. This "first light" is seen today as the CMB."

Ouch!

Looks like it needs some work to get this right.

And in more ways than one.

 

[Classical Motion]

AI is going to affect our lives much more than the internet did. Get use to it.

 

[Unclear Engineer]

If that was "AI", then it is short for "Automated Incompetence".

And, it seems incredible that any journalist, or editor, would simply trust "AI" to do their jobs for them, without even proof reading the output!

Maybe the basic problem is that the "AI" developers are "training" their products with stuff gleaned from the Internet. So, it just mimics the average stupid response one would get from the Internet, rather than what one would get from actual experts.

I suggest that if you want to mimic experts, you need to train with the experts, not the average Joes (and Josephines) with the spare time to dominate the content of the Internet. Train it with curated information from reliable expert sources, and you will at least get automated knowledge.. But, to get automated intelligence, they need to develop automated critical thinking. And that seems a long way off.

While critical thinking is still lacking in these automated products, it is the jobs of the authors and editors to supply it. Clearly, that was not done for this article.

 

[Helio]

Then it says:
"When the first stars formed, their intense radiation ripped electrons from neutral hydrogen once again, an event called "reionization," turning the universe dark again during an epoch known as the 'Cosmic Dark Ages."'

But, that would mean that we are still in the "cosmic dark ages", even now with the hydrogen ionized, still. So, why could we seen anything by a white haze? Oh, maybe because the authors think "opaque" means "transparent"?!

Good catch. The article seems false here. The Dark Ages following the first Reionization (CMBR light) came as a result of the newly formed atomic hydrogen cooling and forming H2, which is opaque to visible wavelengths. [Think Bok globules.] The first stars would have ionized molecular hydrogen to the point where more and more visible light would pass. The redshifting of the light due to expansion plays a role, especially regarding the Lyman Alpha Forest.

The proper explanation can be found here.

 

[Unclear Engineer]

One of the things that bothers me about explanations like the one in Helio's link is that somehow, the CMBR that supposedly was emitted when neutral hydrogen was formed made it through that "opaque" dense hydrogen that was present in the "dark ages" supposedly created by the neutral hydrogen.

How are we seeing "light" (now microwaves) that was emitted before the "dark ages" and must have passed through it to be seen now? i do understand the theory that space expanded and stretched the light photons into microwaves, but that supposedly did not occur instantaneously. So, what is the explanation for how the CMBR made it through the "opaque" hydrogen gas?

 

[Helio]

One of the things that bothers me about explanations like the one in Helio's link is that somehow, the CMBR that supposedly was emitted when neutral hydrogen was formed made it through that "opaque" dense hydrogen that was present in the "dark ages" supposedly created by the neutral hydrogen.

This topic is often poorly explained and I still don't have a clear understanding of how we see light from the earliest moments. Perhaps chronological stages will help, including for me:

• The Bang giving us “pure” energy, as Spock called it.
• About 1 in 10 nuclei are He. Beginning around 18k years, electrons began combining with He to form the first atoms. [I know, we usually only hear the H story.]
• At about 47k years, matter has more effect on the universe than radiation.
• At around 100k years, the first molecules forms (helium hydride; HeH+).
• At about 380k years, we get Recombination for hydrogen, forming neutral atomic hydrogen. This captures the free electrons, which allows light to propagate freely. It is this light that we see as the CMBR. [Keep in mind that as the universe expanded further the wavelengths redshifted, which allowed propagation through zones that would otherwise be “opaque”.]
• [But you’ll read about atomic hydrogen emitting copious amount of light at cm wavelengths. So did the 3000K temp. prevent this behavior, or was it really too trivial to upset the near perfect BB distribution?]
• Next came increasing concentration of hydrogen in the areas of the anisotropy, both of matter and dark matter. This concentration of hydrogen disrupted the propagation of visible light. But perhaps the CMBR light had redshifted enough during this period to allow passage. I’m not clear on this. Regardless, the concentration of light around areas that formed stars and galaxies became dark.
• After bout 200 million years or so, the first stars forms, along with protogalaxies, including the formation of early filaments of galaxies.
• Later, and gradually, the starlight lead to a period of reionization. This ended the Dark Ages allowing visible light propagation due mainly, I think, to the much lower density in the now expanded universe.

Most of the above can be found in Wiki here.

How are we seeing "light" (now microwaves) that was emitted before the "dark ages" and must have passed through it to be seen now? i do understand the theory that space expanded and stretched the light photons into microwaves, but that supposedly did not occur instantaneously. So, what is the explanation for how the CMBR made it through the "opaque" hydrogen gas?

I think the answer is both in redshift and lower density.

The behavior of H also confuses my interpretation of what happened. So how is this best understood during the first "Recombination"? I don't know.

Ionized hydrogen blocks visible light, but it emits copious amount of cm wavelengths.

And molecular hydrogen (H2) is non-reactive to visible light, hence dark regions of it block light, but dust more so, apparently.

 

[Unclear Engineer]

But redshift and lower density did not happen faster than light can be absorbed. And from what I have read, the CMBR frequency distribution looks like red-shift black body radiation rather than red shifted absorption and emission lines for the various forms of hydrogen.

It just strikes me as a lot of arm waving when I read about it.

Perhaps somebody has a simulation model that performs the theorized emissions and absorptions over the postulated time frames and demonstrates the observed CMBR properties? If so, then I would think there is a better explanation somewhere.

 

[Unclear Engineer]

Here is an article that makes more sense, and also mentions a simulation for at least the end of the "dark ages" to make comparisons with observations. https://phys.org/news/2025-06-hours-square-kilometer-array-cosmic.html

But, I am still looking for a simulation that goes back to the supposed CMBR emission and tracks that through the dark ages.