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So, we can "see" 13.7 billion (intentionally not including expansion) light years in all directions and we "see" a red shift.

What if, the reason we can't observe photons beyond this limit is that they decay into a low energy-high mass dark matter particle after 13.7 billion years?

The initial decay process produces the red shift with a quantum decay to dark.

Perhaps our universe is many times older than 13.7 billion years and the decay from the past light is the dark matter we seek, and our universe is not expanding, and we do not need to find dark energy to explain expansion.

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closed as unclear what you're asking by WillO, Aaron Stevens, ZeroTheHero, Jon Custer, John Rennie Jan 15 at 7:01

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    $\begingroup$ "I have a hard time understanding/believing that the earth is at the center of our observable universe. (i.e 13.7 billion light years in all directions from us)" All points in a homogeneous universe are at the center of the regions that they can observe. $\endgroup$ – D. Halsey Jan 14 at 14:54
  • $\begingroup$ If photons could decay into dark matter particles, then collisions between dark matter particles should produce photons. There would be photons popping into existence in places where no normal charged matter is present. Have we ever seen any such events? $\endgroup$ – Lewis Miller Jan 14 at 16:30
  • $\begingroup$ If photons could decay they would have some probability of decaying per unit time. But photons experience no proper time, so they can't decay. $\endgroup$ – tfb Jan 14 at 19:22
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It seems that you have a lot of confusion about the observable universe, dark matter and etc.

So, we can "see" 13.7 billion (intentionally not including expansion) light years in all directions and we "see" a redshift.

We can see further than that. The universe is 13.7 billion years old but due to the expansion of the universe, we can see further than the 13.7 Billion ly. The radius of the observable universe is actually 46.6 Billion ly.

What if, the reason we can't observe photons beyond this limit is that they decay into a low energy-high mass dark matter particle after 13.7 billion years?

We can't see beyond the observable universe because simply the light from there has not reached us yet. It has nothing to do with DM.

I have a hard time understanding/believing that the earth is at the center of our observable universe. (i.e 13.7 billion light years in all directions from us)

There's no center for the universe. We cannot define center in a homogeneous and isotropic universe. It's just a contradictory idea with homogeneity and isotropy. Look this The Cosmological Principle

For the observable umiverse we can define ourselfs as in the center due to the particle horizon.

Perhaps our universe is 20 times older than 13.7 billion years and the decay from the past light is the dark matter we seek, and our universe is not expanding, and we do not need to find dark energy to explain expansion.

Our universe cannot be 20 times older. The CMBR radiation, redshift data from other galaxies (Hubble Law), and the Friedmann Equation can give a highly good result about the age of the universe, And its 13.7 Billion year.

Photons do not decay.

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  • $\begingroup$ This is a good answer overall, except “There's no center for the observable universe”. There is no center for the universe, but earth is the center of the observable universe $\endgroup$ – Dale Jan 14 at 23:26
  • $\begingroup$ Indeed. Sometimes it's hard for me to accept the central idea in general. It seems to me that we are not actually the center of something. Its just comes from the definitions. $\endgroup$ – Reign Jan 15 at 5:25
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    $\begingroup$ Good update, +1 from me $\endgroup$ – Dale Jan 15 at 5:34
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To your question : I have a hard time understanding/believing that the earth is at the center of our observable universe. (i.e 13.7 billion light years in all directions from us)

Well firstly there is no centre of the universe for those are living inside it.. You can not define the state of a system by being inside that very system. Its only possible if you are outside the system observing it. In fact the universe in actually around 46 billion light years in radii. And the limit that you can look at is 13.8 billion light years and that's simply because light have travelled only that much distance since the beginning.

Next you can choose any fixed point and consider it as the center of the universe(just for your happiness!!) and make measurements... Simply because being in a Homogenous Universe won't make a difference as to where you are and in which direction you make the measurement, the farthest galaxies you observe will then also be within boundary limit of universe.

Finally, about your proposition. Whether photon could form dark matter and possibly if the universe is much older than we are thinking. Well yes it might be that the universe is much older than we measure... In fact once at a point in the history of cosmology, Scientists even believed that the Universe is 1.8 Billion years Old while Earth was considered to be around ~ 4.5 billion years old. What ?? But we transcended from that point to today where we do know that the Universe is 13.8 billion years old.. And this must be no surprise to us of tomorrow we wake up and find the sign that the universe is much older and prove it by observing the unobservable. Science progresses that way. Its always from not knowing something to have transition into a better understanding of the scene. So YES it !maybe that universe is older but we are not sure yet !!!

And for if photon decay into dark matter, I really don't think photons decay, because they don't experience time.

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