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Red shift interpretation

  1. Jul 17, 2014 #1
    When a photon loses a little bit of energy, its frequency lows a little. That is, it suffers a slight redshift.
    So, why to interpret the redshift as being only due to the expansion of the Universe?
  2. jcsd
  3. Jul 17, 2014 #2


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    The basic interpretation of the red shift is that the source-receiver separation is increasing. The expansion of the universe is the explanation of why distant galaxies are all receding from us.
  4. Jul 17, 2014 #3


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    Strictly speaking, it is not entirely due to the expansion. There is s a trivial (by comparison) amount of actual proper motion between galaxies and it may be towards or away but it is so inconsequential compared to the recession speed that it is irrelevant.

    What would you like to interpret it as?
  5. Jul 17, 2014 #4


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  6. Jul 17, 2014 #5
    I think that it could also be that the photons, when traveling between the source and the observer, have some loss of its energy (because of some interactions happening on that travel) and so, with less energy, they will appears as red shifted. Of course that this hypothetical phenomena must be uniform at all the emitted spectrum, as we see in fact.

    This effect is real or not? if yes, can we estimate its value? it will introduce some additional imprecision to the computed distances?

    Thanks to all
  7. Jul 17, 2014 #6


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    The "tired light" theory was thoroughly debunked years ago.
  8. Jul 17, 2014 #7
    Thanks to all by the replies given to my nerd questions. All the best.
  9. Jul 18, 2014 #8
    I think the forums need one on the sociology of science. There are so many examples every minute where there's a meta context that is never discussed. The rampant anthropomorphizing in science writing/reporting is a big one. The very alive and well "alpha-primate" syndrome that still drives so much research money and documentaries in a discipline that touted 400 years ago, "We don't cow-tow to authority". And the way people interact with it. One you see everyday on various threads is the person that has come up with a brilliant idea- I've a theory that is contrary to everything anyone has every thought; I am brilliant- but they can't master English, which thousands manage every day. You see it with conspiracy theorists a lot. "I can't hold a job, move out of my parents' house, manage a relationship, get an education...but I've figured out all the things you don't understand about cold fusion". Or HAARP. I think it's worthy of a DSM category!
  10. Jul 18, 2014 #9


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    I understand your thoughts. I, too, discovered PF at a time that I wanted to express and 'bounce' my own ideas off of a more knowledgable community. I was a "lurker" here for almost a year before registering, and the majority of my posts since then have been focused on to trying to help others.

    I've grown to embrace the concept of PhysicsForums. The goal and success is based on being a place where all visitors can depend on seeking to better understand mainstream, peer-reviewed concepts in all areas of sciences. There are other places/forums on the internet that cater to extended interpretations and/or philosophical suggestions, and I for one am glad that they're separate from PF. It's important to me to know that that my questions and inquiries are 'kept in check' towards my better understanding of mainstream science.

    Just my $.02.
  11. Jul 18, 2014 #10


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    As Tublingdice said, you misunderstand the purpose of the PF. We are not here to debunk nonsense but simply to help folks understand mainstream physics. People who are as you described, thinking they have come up with something brilliant when they understand very little, are not the point of this forum and PF wastes no time on them or on discussions of them.
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