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B Speed of Light in Dark Matter

  1. Jun 14, 2018 #21

    Drakkith

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    Yes, but skewed how? What would the observable effects be? It can't be anything too drastic, as we don't observe sudden, extreme shifts in the properties of incoming light. The issue is that our current model is remarkably well supported with very little evidence to point to where it may be inaccurate. For example, the redshift and the angular size of galaxies follow each other fairly closely. We don't find galaxies with high redshift that are also very large (angular size). The highest redshift comes from galaxies which are barely larger than a handful of pixels. Nor do we find sudden shifts in the light when we move our observations between galaxies or clusters into the voids between them. In fact, the CMB can be seen when looking through these galaxies, and there is no known association between the placement of these galaxies, clusters, and voids and a change in the CMB as far as I am aware.

    If the permittivity and permeability of space changes over time or distance, it changes in such a way as to make it look extraordinarily similar to the expanding universe that the standard cosmological model represents.
     
  2. Jun 15, 2018 #22

    Sanborn Chase

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    What if all observations have been skewed, and skewed how is unknown? A link in the inductive chain may be in question. Perhaps the question should be the speed of light without dark matter present. And, again, I labelled this original post as "B" high school level because they didn't offer elementary school level.
     
  3. Jun 15, 2018 #23

    Drakkith

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    What if they haven't been skewed? Just asking what if they've been skewed isn't a very useful question without something more specific to talk about.

    Or there may be nothing wrong with our understanding of the speed of light. That's why you need evidence to point to that can't be explained by the standard model but can be explained with another.

    I don't mean to shut down your question, but you could ask "What if X is wrong" about anything at all and in any variation. What if our understanding of the speed of light through dark matter is incorrect, but in a way that we don't know and that looks like something else that we can explain through the standard cosmological model? Well then we're wrong and we don't know it!
     
  4. Jun 15, 2018 #24

    Sanborn Chase

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    Dear Mr. Drakkith, I can't tell you how much I appreciate your very kind responses to my questions. You've been patient and informative with me, and I know you sense my ignorance and lack of understanding. Perhaps it would help if I explained where my attention is centered.

    When I was about ten years old my father and I ground an eight inch mirror and built a reflecting telescope. Certainly I didn't understand what exactly we were doing until one night after its completion he aimed it at the night sky, and I stood on my little stool and looked in the eyepiece. There was Saturn about the size of a dime with all of the colors and rings! My heart just melted; not just about seeing another world, which was so amazing to me, but because my father cared enough about me to wish to share this with his son. I wanted to be an astronomer and learn all I could about that glorious mysterious world out there. My future was settled.

    Shortly after this that poor man died of a heart attach, and my life changed completely. I could no longer pursue my dream as necessities eclipsed desires. But I've never lost my sense of awe, and for the next sixty years I've read and studied as much as time allowed in pursuit of those secrets.

    When I found these forums I was thrilled. After thoroughly reviewing the protocols and rules protecting the use of them, I decided to join and have never regretted it. I'm completely fascinated by the subjects and responses to these threads. Occasionally, I screw up my courage and ask dumb questions. I realize to some of you with a great deal of quite remarkable knowledge you perceive how sophomoric they seem, but I can't help myself. For I I know I'm standing with giants.

    If you have the power to "shut down" my questions, and they seem to have irritated you in some manner, go ahead. But as far as I'm concerned I've paid my money, and I'll take my choice. I hope you won't; there seem to be others interested, too.
     
    Last edited by a moderator: Jun 15, 2018
  5. Jun 15, 2018 #25

    Drakkith

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    On the contrary, I'm not irritated at all (nor do I have the power to shut you down). I'm merely explaining that 'what if' questions are inherently very difficult to answer because there are potentially an infinite amount of other possibilities and we need some way of narrowing things down. That's why I stressed the need for observations that are difficult for the standard model to explain. Dark matter was conceived as an idea after observations revealed things that the standard model couldn't explain, like the odd galaxy rotation curves and the fact that there appears to be a lot of mass in places that we can observe little to no matter. The inability of our standard model to explain these prior to the introduction of dark matter is exactly the sort of thing that I'm talking about. We had clear evidence that something wasn't quite right with our standard model so we gathered more evidence and eventually came up with and refined the idea of dark matter.

    When it comes to the speed of light, we don't have anything similar. There are no observations that would lead us to believe that the speed of light is different in different parts of the universe, so we have no reason to even look for something that could cause this. Like I said, the number of possible things that might be wrong but that we haven't observed is potentially infinite, so we need something to point to and say, "Look! That's not right!"
     
  6. Jun 15, 2018 #26

    Sanborn Chase

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    Thank you very much for your thoughts; I'm happy I've not irritated you, Mr. Drakkith.
    I've been following the literature about dark matter for a number of years. I understand very little of the technical arguments as mathematically expressed (I wilted shortly after calculus), but the concepts surrounding the mystery of dark matter have continued to amaze me, and I realize its quantification is cardinal to our understanding of our world. I also think it's extremely important to understand its nature, and so far there hasn't been a profound breakthrough. It deserves our closest scrutiny. In my life all too often my ignorance has hidden behind my certainty.
    BTW. I doubt Greg B. wants me cross talking so much. I'll cease and desist as of now.
    Again, thanks for everyone's opinions and thoughts.
     
  7. Jun 16, 2018 #27
    Thanks Drakkith, and I agree. Which makes me wonder... given that researchers are converging towards two very precise, but different, values for a "Hubble constant", would this qualify as a pointer to something that may turn out to be "difficult for the standard model to explain"?

    https://www.scientificamerican.com/...on-universes-expansion-polarizes-scientists1/

    Nigel
     
  8. Jun 17, 2018 #28

    Drakkith

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    It might. It depends on whether there's a true difference vs a measurement error or something.
     
  9. Jun 17, 2018 #29
    Sorry for expanding this aside, but let me sum up the article.
    1. The expansion rate was 67.3 km/s/Mpc in the early universe
    2. The expansion of the universe is accelerating
    3. Today, the expansion rate is 73.5 km/s/Mpc.
    I fail to see a problem here...?
     
  10. Jun 17, 2018 #30

    Ken G

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    Acceleration doesn't mean the Hubble parameter should increase. Without acceleration, it should drop with age, and the steepest type of acceleration that is normally treated is one in which the Hubble parameter stays fixed with age, which might be a situation we are now moving toward as dark energy wrests control. But it would be a significant problem for current models if the Hubble parameter increased with age.
     
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