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Thread: Red shift

  1. #1 Red shift 
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    In whatever direction we observe the universe we are looking into the past. That means, assuming an expanding universe, that we are looking at a smaller universe, despite the evidence of our senses. If we look far enough, in any direction, we will be looking at a singularity or whatever existed at the origin of the universe. Although we appear to be seeing far distant objects as if in the inside of a vast sphere, these objects are in fact relatively close together in a much more compact volume. Any thought of some objects being separated by a distance, greater than could have been accomplished within the apparent lifetime of the universe without exceeding the speed of light, is spurious. Can anyone tell me the effect on the wavelength of light pass​ing through expanding space? Is it red shifted??


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    Any thought of some objects being separated by a distance, greater than could have been accomplished within the apparent lifetime of the universe without exceeding the speed of light, is spurious.

    You see to be confused. Objects are moving away from each other faster than the speed of light due to the expansion of the universe. Actual motion cannot exceed the speed of light.


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    Quote Originally Posted by BobJeffs View Post
    In whatever direction we observe the universe we are looking into the past. That means, assuming an expanding universe, that we are looking at a smaller universe, despite the evidence of our senses. If we look far enough, in any direction, we will be looking at a singularity or whatever existed at the origin of the universe.


    Actually, no. If we run the clock backwards from the present, we find the universe to be opaque before we get to the bang, so we cannot see earlier than that, regardless of the resolving power of future technology [a possible loophole, being explored theoretically, involves probing that early epoch using other than photons]. Google for the term "surface of last scattering".

    Although we appear to be seeing far distant objects as if in the inside of a vast sphere, these objects are in fact relatively close together in a much more compact volume. Any thought of some objects being separated by a distance, greater than could have been accomplished within the apparent lifetime of the universe without exceeding the speed of light, is spurious.
    That's what one might believe from a common misreading of relativity, such as one might get from having read only poorly-written popularisations of science, rather than studying relativity in some detail. If you do undertake that additional study, you find that there is no prohibition against space expanding superluminally, carrying with it matter contained within. So distant objects can indeed have a recession velocity far in excess of c, without contradicting any known laws of physics, so nothing is "spurious" at all about this observation. Google for the term "metric expansion of space".

    "Can anyone tell me the effect on the wavelength of light pass​ing through expanding space? Is it red shifted??


    And yes if space is stretching, so are the wavelengths of light. The metric expansion of space gives us the famous observed redshift.
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    Why then is the observed red shift interpreted and indicating solely recessional velocity?
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    How then does the light reach us?
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    How then does light pass from one body to another ie. our own planet.
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    Quote Originally Posted by BobJeffs View Post
    Why then is the observed red shift interpreted and indicating solely recessional velocity?
    I don't understand the "then" in your question. It seems a non-sequitur to what I wrote.
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    Quote Originally Posted by BobJeffs View Post
    How then does the light reach us?
    Another non-sequitur. It is almost as if you are ignoring what I wrote, and then simply listing a series of barely related questions.

    You would benefit greatly from studying Ned Wright's cosmology faq and tutorial pages (google for it; he's a UCLA prof., he was a PI on WMAP and COBE, among other accomplishments).

    As to your latest question, not all light reaches us. Some will be forever out of reach, so your question presumes an erroneous premise. Other light can reach us, and will eventually. Still other light is reaching us now.
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    Thank you for the input. My responses on 23 July were supposed to relate to specific items but due to my inexperience of this website I am at a loss to know how to link them.
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    And yes if space is stretching, so are the wavelengths of light. The metric expansion of space gives us the famous observed redshift.

    Why then is the observed red shift interpreted as indicating solely recessional velocity? Ignore this I'm just practising!!
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    Red shift indicates recessional velocity. This can come from two sources, expansion of the universe or actual motion. For most galaxies it is the expansion.
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    I've always been bothered by the observed red shift too. I'm not smart enough to understand the physics, but it seems unlikely to me that the observed red shift should be the same in all directions. Which it apparently is.

    I wonder if time is somehow involved.

    Einstein introduced the idea that time is not a constant, that time can slow down under extreme gravity (near a black hole) -- or presumably at the singularity of a Big Bang? Is it not possible (he asked na´vely) that time is speeding up as the universe expands, so when we look backwards in time to distant galaxies, they're red shifted to a slower timeframe?
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    Quote Originally Posted by NoCoPilot View Post
    I've always been bothered by the observed red shift too. I'm not smart enough to understand the physics, but it seems unlikely to me that the observed red shift should be the same in all directions. Which it apparently is.

    I wonder if time is somehow involved.

    Einstein introduced the idea that time is not a constant, that time can slow down under extreme gravity (near a black hole) -- or presumably at the singularity of a Big Bang? Is it not possible (he asked na´vely) that time is speeding up as the universe expands, so when we look backwards in time to distant galaxies, they're red shifted to a slower timeframe?
    Red Shift is also caused by gravity itself, yet the ratio to doppler/gravity have not been determined, nor applied to any object. It seems that it hasn't even been studied as co-existing.
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    Quote Originally Posted by justoldbob View Post
    Red Shift is also caused by gravity itself, yet the ratio to doppler/gravity have not been determined, nor applied to any object. It seems that it hasn't even been studied as co-existing.
    The ratio of Doppler to gravitational red-shift is easy to calculate (it depends on the ratio of relative speed and difference in gravitational potential). They have also both been measured to confirm that the calculations are correct. It is actually relevant to GPS systems.

    Both are largely irrelevant to cosmological red-shift.
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    True to local area and not to great accuracy, but how about 13.9 Billion Light years distance? I just cannot trust observation, calculation and actual effects on that distance scale.
    Thank you for thinking about it with me. Data will always change and the concepts associated with it will also.
    By the way, where is Northamptonshire?
    Bob
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    Quote Originally Posted by justoldbob View Post
    True to local area and not to great accuracy, but how about 13.9 Billion Light years distance?
    What about it? Why wouldn't the same physics apply as locally? (Note that we cannot observe anything (directly) at that distance)

    I just cannot trust observation, calculation and actual effects on that distance scale.
    You don't trust the measurements? And you don't trust arithmetic. So you don't trust any science. Not sure why you are posting on this forum.
    ei incumbit probatio qui dicit, non qui negat
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  18. #17  
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    Quote Originally Posted by justoldbob View Post
    True to local area and not to great accuracy, but how about 13.9 Billion Light years distance? I just cannot trust observation, calculation and actual effects on that distance scale.
    So you think that we're in some sort of privileged position in the universe?
    What do you base that on?
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    Quote Originally Posted by Strange View Post
    Quote Originally Posted by justoldbob View Post
    True to local area and not to great accuracy, but how about 13.9 Billion Light years distance?
    What about it? Why wouldn't the same physics apply as locally? (Note that we cannot observe anything (directly) at that distance)

    I just cannot trust observation, calculation and actual effects on that distance scale.
    You don't trust the measurements? And you don't trust arithmetic. So you don't trust any science. Not sure why you are posting on this forum.

    My gripe is not with the science or the math. It is the interpretation of the data. Far too many scientists are stating as fact, some observations based on 'assumptions'. When teachers do it, it bothers me quite a bit.
    For instance can you determine the difference between a Gaussian blurring to a Inverse square blurring of a galaxie billions of light years away? They appear identical but mathematically are very different.
    Study is only now starting to be able to attempt to determine ratios of cosmological redshifting to gravitational redshifting, and even that is at a local distance. Mass of Galaxies are currently being based on luminosity only, even though we know that gravitational redshifting must be occuring.
    Instead of stating something as 'fact' it should be stated 'we think' untill it is proven, other wise some may be led away from investigation into some things not yet proven.
    Bob

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    You had previously been given a hint.
    Now it's more than that: don't post in the hard science sub-fora in future.
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    Quote Originally Posted by Dywyddyr View Post
    You had previously been given a hint.
    Now it's more than that: don't post in the hard science sub-fora in future.
    It's great being a moderator because even when you are a total dumbass you can always tread over everyone else and claim to be right.

    Hint. You are a dumbass.
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    Quote Originally Posted by MikeinSpain View Post
    Quote Originally Posted by Dywyddyr View Post
    You had previously been given a hint.
    Now it's more than that: don't post in the hard science sub-fora in future.
    It's great being a moderator because even when you are a total dumbass you can always tread over everyone else and claim to be right.

    Hint. You are a dumbass.
    Oh good, chuckles is back, for a moment anyway...
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  23. #22  
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    Quote Originally Posted by justoldbob View Post
    My gripe is not with the science or the math. It is the interpretation of the data.
    The interpretation is the theory; unless you can show some specific errors in the mathematics or the data, I don't know what you are talking about.

    Far too many scientists are stating as fact, some observations based on 'assumptions'.
    Scientists rarely state things as fact (although science journalists often do). There are some theories that are swell evidenced that they can be considered pretty close to "facts" (such as evolution by natural selection, general relativity, the Big Bang model of the universe, etc.)

    For instance can you determine the difference between a Gaussian blurring to a Inverse square blurring of a galaxie billions of light years away? They appear identical but mathematically are very different.
    If they appear identical then, presumably, it doesn't matter which model you use. There are plenty of examples in science where two models can be used with equal validity. Until more data is available, or it is found that the model only works in some cases.

    Study is only now starting to be able to attempt to determine ratios of cosmological redshifting to gravitational redshifting, and even that is at a local distance.
    Citation needed. These are completely different effects.

    Mass of Galaxies are currently being based on luminosity only, even though we know that gravitational redshifting must be occuring.
    How is red shift relevant to luminosity? (Or, if it is, why wouldn't it be taken into account when calculating the luminosity?)

    Instead of stating something as 'fact' it should be stated 'we think' untill it is proven, other wise some may be led away from investigation into some things not yet proven.
    That is pretty much how scientists normally state things. (If they don't it is because they know their audience will know that is what is meant.)

    And nothing is ever proven in science so you are setting ridiculous standards.
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    [QUOTE=Strange;625036]
    Quote Originally Posted by justoldbob View Post
    My gripe is not with the science or the math. It is the interpretation of the data.
    The interpretation is the theory; unless you can show some specific errors in the mathematics or the data, I don't know what you are talking about.

    Far too many scientists are stating as fact, some observations based on 'assumptions'.
    Scientists rarely state things as fact (although science journalists often do). There are some theories that are swell evidenced that they can be considered pretty close to "facts" (such as evolution by natural selection, general relativity, the Big Bang model of the universe, etc.)

    For instance can you determine the difference between a Gaussian blurring to a Inverse square blurring of a galaxie billions of light years away? They appear identical but mathematically are very different.
    If they appear identical then, presumably, it doesn't matter which model you use. There are plenty of examples in science where two models can be used with equal validity. Until more data is available, or it is found that the model only works in some cases.

    Study is only now starting to be able to attempt to determine ratios of cosmological redshifting to gravitational redshifting, and even that is at a local distance.
    Citation needed. These are completely different effects.

    Mass of Galaxies are currently being based on luminosity only, even though we know that gravitational redshifting must be occuring.
    How is red shift relevant to luminosity? (Or, if it is, why wouldn't it be taken into account when calculating the luminosity?)

    Instead of stating something as 'fact' it should be stated 'we think' untill it is proven, other wise some may be led away from investigation into some things not yet proven.
    That is pretty much how scientists normally state things. (If they don't it is because they know their audience will know that is what is meant.)


    1) Then you need to study more.
    2) Don't you listen to any of them?
    3) Again, you need to study more.
    4) Which is the reason we need to determine the ratio of the two.
    5) Once again, you need to study more.
    6) Then they are making assumptions, as are you in determining what they know.
    7) The standards have to be strict. As far as 'ridiculous' standards that is only an 'opinion'.
    And again, where is Northamptonshire?
    Bob
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  25. #24  
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    Quote Originally Posted by justoldbob View Post
    4) Which is the reason we need to determine the ratio of the two.
    The ratio will depend on the distance (amount of cosmological redshift) and the difference in gravitational potential (gravitational redshift). The latter is rarely significant; it requires very precise measurements to detect. And as cosmological redshift increases, it becomes less significant.

    I'm not even sure why you think it is an important ratio to know about.

    6) Then they are making assumptions, as are you in determining what they know.
    I don't know who "they" are or what assumptions that mare making. So I'm not sure what point you are trying to make.

    7) The standards have to be strict. As far as 'ridiculous' standards that is only an 'opinion'.
    Maybe. But nothing is ever proven in science.

    where is Northamptonshire?
    LMGTFY: https://en.wikipedia.org/wiki/Northamptonshire
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    Quote Originally Posted by Strange View Post
    Quote Originally Posted by justoldbob View Post
    4) Which is the reason we need to determine the ratio of the two.
    The ratio will depend on the distance (amount of cosmological redshift) and the difference in gravitational potential (gravitational redshift). The latter is rarely significant; it requires very precise measurements to detect. And as cosmological redshift increases, it becomes less significant.

    I'm not even sure why you think it is an important ratio to know about.
    Hello Strange,
    I apologize for being short in my earlier response but I was pressed for time.
    Actually gravitational redshift also depends on distance and at these scales do become significant. By determining the ratios at which these affect the overall redshift may give us a better idea of these distances and mass's.
    The reason the Gaussian blurring and Inverse square blurring are important is to help determine the extent of the central mass, where as an inverse square blurring is simply a cone centered at a point.
    And finally the "they" are the scientists you say know what the audiances know and understand.
    I just suggest that you prove to yourself what to believe and not just take someones statement as fact. You will be doing yourself a favor as well as the researcher, and may be suprised at a new viewpoint.
    Bob



    6) Then they are making assumptions, as are you in determining what they know.
    I don't know who "they" are or what assumptions that mare making. So I'm not sure what point you are trying to make.

    7) The standards have to be strict. As far as 'ridiculous' standards that is only an 'opinion'.
    Maybe. But nothing is ever proven in science.

    where is Northamptonshire?
    LMGTFY: https://en.wikipedia.org/wiki/Northamptonshire
    Also I will look up Northamptonshire .
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  27. #26  
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    See you in 3 days.
    When/ if you come back don't post in the hard science sub-fora in future.
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  28. #27  
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    Quote Originally Posted by justoldbob View Post
    Actually gravitational redshift also depends on distance and at these scales do become significant. By determining the ratios at which these affect the overall redshift may give us a better idea of these distances and mass's.
    Gravitational only depends on the difference in gravitational potential. That may vary with distance but it could be the same at different distances, or different at the same distance.

    As it is trivial to calculate the relative effects, why don't you show that it would make a significant difference?

    And finally the "they" are the scientists you say know what the audiances know and understand.
    I was referring to scientists talking (or writing for) other scientists.

    I just suggest that you prove to yourself what to believe
    Nothing is ever proved in science. (That sounds oddly familiar for some reason)
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  29. #28  
    Brassica oleracea Strange's Avatar
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    I just suggest that you prove to yourself what to believe and not just take someones statement as fact. You will be doing yourself a favor as well as the researcher, and may be suprised at a new viewpoint.
    That is rather ironic as your Vixra "paper" asks people not to be critical and just accept what you say "because you are a genius".

    Here, I'll do a another Google search for you: https://en.wikipedia.org/wiki/Dunning–Kruger_effect
    ei incumbit probatio qui dicit, non qui negat
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