Click the link below the picture
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When it comes to the Universe, there are some things we can be confident are out there based on what we observe. We know that the Universe was hotter, denser, and more uniform in the distant past. We know that the stars and galaxies in the Universe have grown up and evolved as the Universe has aged. We know that gravitation has formed the large-scale structure in the Universe, and that structure has grown more complex over time. And we also know how much normal matter, altogether, is present in the Universe, and that it isn’t sufficient to explain the full suite of the gravitational effects that we see on its own.
So if the normal matter can’t be all that there is, what else can there be? The leading idea is dark matter, but we don’t know precisely what it is. What if it’s just light? Is that possible? That’s what Enon Travis Sci wants to know, asking:
“I’d love to read an article on why light isn’t a dark matter candidate, especially in light (pun intended) of the recent articles about the 50% excess in ambient light in the universe, and the known phenomena of apparent mass photons can have on spacetime…”
It’s a completely reasonable idea to consider. Let’s take a look inside.
First off, there really is an excess in the ambient light we see in the Universe. In fact, I myself wrote about it back in 2020, because it’s one of the most intriguing things that the New Horizons spacecraft was able to measure from its unique location: out beyond the orbit of Pluto. Among all fully functioning spacecrafts, only New Horizons is distant enough to be immune to the tiny, light-reflecting dust grains that exist all throughout our Solar System, and see what sort of light still remains.
Is deep space entirely dark?
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(Credit: IceCube collaboration/NASA) In this artistic rendering, a blazar is accelerating protons that produce pions, which produce neutrinos and gamma rays. Lower-energy photons are also produced. We believe this object, like all galaxies and larger ones, is surrounded by a dark matter halo. But what is that halo composed of, and could heavy photons be an option?
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Click the link below for the article:
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James' World 2 
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