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  1. #1 cosmological redshift 
    Forum Freshman Robbedoes's Avatar
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    What causes cosmological redshift do you think?


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    This is all off the top of my head, didn’t look any of it up, be a test for me here.
    I’m gonna say expansion/inflation. Look up the Hubble constant. Though it has been observed to not be constant, accelerating actually.


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    Quote Originally Posted by GiantEvil View Post
    This is all off the top of my head, didn’t look any of it up, be a test for me here.
    I’m gonna say expansion/inflation. Look up the Hubble constant. Though it has been observed to not be constant, accelerating actually.
    How is the hubble constant created?
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    Probably something with dark energy, and the cosmological constant.
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    Redshift is due to universe expansion. Observation that expansion is accelerating is explained by cosmological constant.
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    Quote Originally Posted by mathman View Post
    Redshift is due to universe expansion. Observation that expansion is accelerating is explained by cosmological constant.
    Explained?

    I thought the cosmological constant was just the factor you need to have in your maths to model the expansion. That's far from being an explanation of it.
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    Quote Originally Posted by mathman View Post
    Redshift is due to universe expansion.
    And the accelerated expansion is 'observed' via the redshift?
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    Quote Originally Posted by Robbedoes View Post
    Quote Originally Posted by mathman View Post
    Redshift is due to universe expansion.
    And the accelerated expansion is 'observed' via the redshift?
    It is observed by how redshift varies with distance. If there were a direct relationship between Redshift and distance, then this would indicate a constant rate of expansion.
    If the relationship is direct or changes with distance, this indicates that the universe has not been expanding at a fixed rate, but that rate has changed over time*. The most recent measurements of this relationship indicate that the rate of expansion is increasing with time.

    *Remember that as we look at galaxies further and further away, we are seeing them as they were further and further back in time. So when we measure the red shift from a distant galaxy, we get a measure of its rate of recession at that point in time. Looking at galaxies at different distances also gives us a map of how the rate of expansion has changed over time.
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    Quote Originally Posted by Robbedoes View Post
    What causes cosmological redshift do you think?
    The expansion of the universe.
    Quote Originally Posted by Robbedoes View Post
    How is the hubble constant created?
    The red shift is measured by the offset of absorption lines of elements in galaxies.
    The distance to those galaxies is measured by several means. One common method is to look at the difference between the intensity of the light received and the intrinsic intensity of the light emitted from Cepheid variable stars. These stars have a brightness that is proportional to the rate of variability of the stars. The difference in the actual intensity VS intrinsic intensity will indicate the distance based on the 1/r^2 relationship of a point source of light.
    In a graph of red shift VS distance the Hubble Constant is the slope of the line.
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    Quote Originally Posted by Bufofrog View Post
    Quote Originally Posted by Robbedoes View Post
    What causes cosmological redshift do you think?
    The expansion of the universe.
    Quote Originally Posted by Robbedoes View Post
    How is the hubble constant created?
    The red shift is measured by the offset of absorption lines of elements in galaxies.
    The distance to those galaxies is measured by several means. One common method is to look at the difference between the intensity of the light received and the intrinsic intensity of the light emitted from Cepheid variable stars. These stars have a brightness that is proportional to the rate of variability of the stars. The difference in the actual intensity VS intrinsic intensity will indicate the distance based on the 1/r^2 relationship of a point source of light.
    In a graph of red shift VS distance the Hubble Constant is the slope of the line.
    Nice summary. (Like button doesn't work)
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    When we’re talking about cosmological redshift, it isn’t just recessional velocity(i.e. Doppler) is it?
    Is there a component to it, of the wavelength being stretched by the expansion of spacetime?
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    Quote Originally Posted by GiantEvil View Post
    When we’re talking about cosmological redshift, it isn’t just recessional velocity(i.e. Doppler) is it?
    Is there a component to it, of the wavelength being stretched by the expansion of spacetime?
    Physicist say that it is that the light is getting 'stretched' and not the recession velocity, which is not a true velocity, at least it is not a velocity through space. Frankly, I have a hard time wrapping my mind around the concept of a stretched light wave.
    Here is an explanation (of sorts).
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    It seems implied that there is no recessional velocity component to cosmological redshift then, that it is entirely a matter of expanding spacetime.
    But spacetime is relativistic, not a substance that carries the EM wave. But it stretches?
    Hmm... The water is so deep, I don’t even have a proper question. I wish Markus were here, he understands this stuff on the level of the mathematical modeling.
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    Quote Originally Posted by GiantEvil View Post
    It seems implied that there is no recessional velocity component to cosmological redshift then, that it is entirely a matter of expanding spacetime.
    But spacetime is relativistic, not a substance that carries the EM wave. But it stretches?
    Hmm... The water is so deep, I don’t even have a proper question. I wish Markus were here, he understands this stuff on the level of the mathematical modeling.
    I'm not sure it's that weird. What does stretching mean? It means the length dimension increases. So if the metric stretches, that is what you would expect, isn't it? Or Am I missing the point?
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    Well, “stretching” is simple in the context of a medium. But we all know better than “aether”, especially as concerns relativity. So “stretching” is likely a “lie to children”. I suppose a good initial question would be “Just how complicated is the real answer?”
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    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by mathman View Post
    Redshift is due to universe expansion. Observation that expansion is accelerating is explained by cosmological constant.
    Explained?

    I thought the cosmological constant was just the factor you need to have in your maths to model the expansion. That's far from being an explanation of it.
    I get your point. What physicists are trying to do is develop some theoretical explanation for the observation. They use terms such as dark energy and cosmological constant, but as "explanations", they are lacking.
    I
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    Quote Originally Posted by GiantEvil View Post
    Well, “stretching” is simple in the context of a medium. But we all know better than “aether”, especially as concerns relativity. So “stretching” is likely a “lie to children”. I suppose a good initial question would be “Just how complicated is the real answer?”
    It strikes me that there is sometimes a bit of overreaction when people mention "aether". As I understand it, the idea is that spacetime itself behaves in some ways like a "thing" that can be moulded, e.g. by mass. I think I once read that Einstein, when describing his then newly formulated theory, described it as a sort of aether theory in which the aether is not material at all but consists of spacetime. But I may be wrong about this.
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    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by GiantEvil View Post
    It seems implied that there is no recessional velocity component to cosmological redshift then, that it is entirely a matter of expanding spacetime.
    But spacetime is relativistic, not a substance that carries the EM wave. But it stretches?
    Hmm... The water is so deep, I don’t even have a proper question. I wish Markus were here, he understands this stuff on the level of the mathematical modeling.
    I'm not sure it's that weird. What does stretching mean? It means the length dimension increases. So if the metric stretches, that is what you would expect, isn't it? Or Am I missing the point?
    I suppose my problem is I am stuck in classical thinking. Why would a photon stretch, but a proton, atom or larger body does not stretch. Is it because gravity and the strong force overcome the expansion? Further a photon is not 'held together' by gravity or the other forces so it will stretch over time as the universe expands?
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    Quote Originally Posted by Bufofrog View Post
    Quote Originally Posted by exchemist View Post

    I'm not sure it's that weird. What does stretching mean? It means the length dimension increases. So if the metric stretches, that is what you would expect, isn't it? Or Am I missing the point?
    I suppose my problem is I am stuck in classical thinking. Why would a photon stretch, but a proton, atom or larger body does not stretch. Is it because gravity and the strong force overcome the expansion? Further a photon is not 'held together' by gravity or the other forces so it will stretch over time as the universe expands?
    If the metric itself stretches, then I presume that applies to the dimensions of everything. This I imagine would alter the energy gap between atomic orbitals, affecting the emission lines as seen by an observer from a different epoch, and so forth. But we need a proper cosmologist or GR expert now I think as I am starting to speak ex ano.
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    Quote Originally Posted by GiantEvil View Post
    Well, “stretching” is simple in the context of a medium. But we all know better than “aether”, especially as concerns relativity. So “stretching” is likely a “lie to children”. I suppose a good initial question would be “Just how complicated is the real answer?”
    Isn't 'stretching', the increase in wavelength of photons/light? (stretching reduces energy)

    It's imo due to a gravitational field...Cosmo redshift is imo gravitational redshift.
    A star is a massive body so it has a gravitational field.
    How can light 'escape' the star without interacting with the gravitational field?https://en.wikipedia.org/wiki/Gravitational_redshift
    Last edited by Robbedoes; January 25th, 2019 at 03:22 PM.
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    Quote Originally Posted by Robbedoes View Post
    It's imo due to a gravitational field...Cosmo redshift is imo gravitational redshift.
    A star is a massive body so it has a gravitational field.
    How can light 'escape' the star without interacting with the gravitational field?https://en.wikipedia.org/wiki/Gravitational_redshift
    Please do not offer ill-formed opinions in response to questions (even if they're your own!). It muddies the waters and confuses the questioner. Cosmological redshift is not gravitational redshift, your opinions aside. Cosmological redshift is simply due to metric expansion. Gravitational redshift is a separate thing altogether.
    Last edited by tk421; January 25th, 2019 at 07:57 PM.
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    Quote Originally Posted by exchemist View Post
    If the metric itself stretches, then I presume that applies to the dimensions of everything. This I imagine would alter the energy gap between atomic orbitals, affecting the emission lines as seen by an observer from a different epoch, and so forth. But we need a proper cosmologist or GR expert now I think as I am starting to speak ex ano.
    If the metric expansion of space applied uniformly at all length scales and to all objects independently of local forces, then yes, atoms would have expanded until they'd lost cohesion and we would not be here to post about it. Happily for us, the forces within an atom "win", as does the gravitational force (where I use force as shorthand for what GR describes) that binds the stars within a galaxy.

    If one views metric expansion as analogous to the stretching of a membrane, the forces that bind atoms and solar systems should be thought of as altering the local properties of the membrane, making those regions stiffer. So, over cosmologically relevant distances, we see metric expansion work its magic, but locally, not so much.
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    ^ Wouldnt a photon/EM wave be a local thing?
    Okay, my guess; The distances that the “stretching” is taking place over are astronomical. The expansion is likely negligible at its local points. But since the expansion is equal at all points it matters a lot more over long distances?
    Or more mathematically; If the metric on a graph were to expand very slowly, a sine function on that graph would appear more and more stretched as the graph continued?
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    Quote Originally Posted by GiantEvil View Post
    ^ Wouldnt a photon/EM wave be a local thing?
    Okay, my guess;
    No need to guess. The term cosmological expansion conveys what you need to know. We don't see redshifts over human or planetary scales. As much as I would like to, I may not honestly attribute my expanding girth to this effect.

    The distances that the “stretching” is taking place over are astronomical.
    Yes, that's the key. You might enjoy Ned Wright's cosmology calculator: Ned Wright's Javascript Cosmology Calculator

    The expansion is likely negligible at its local points. But since the expansion is equal at all points it matters a lot more over long distances?
    Or more mathematically; If the metric on a graph were to expand very slowly, a sine function on that graph would appear more and more stretched as the graph continued?
    Again, think of the rubber sheet (or balloon) analogy. Expansion is stretching. Lengths (including wavelengths) stretch, which means that the light reddens.
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    Quote Originally Posted by tk421 View Post
    Please do not offer ill-formed opinions in response to questions (even if they're your own!). It muddies the waters and confuses the questioner. Cosmological redshift is not gravitational redshift, your opinions aside. Cosmological redshift is simply due to metric expansion. Gravitational redshift is a separate thing altogether.
    I'm sorry. I've said this before on other fora and I know no one agrees with me.
    How can most redshift be because of metric expansion and some because of gravitation?

    http://hyperphysics.phy-astr.gsu.edu...iv/gratim.html
    Last edited by Robbedoes; January 26th, 2019 at 10:13 AM. Reason: changing word
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    Quote Originally Posted by tk421 View Post
    Quote Originally Posted by exchemist View Post
    If the metric itself stretches, then I presume that applies to the dimensions of everything. This I imagine would alter the energy gap between atomic orbitals, affecting the emission lines as seen by an observer from a different epoch, and so forth. But we need a proper cosmologist or GR expert now I think as I am starting to speak ex ano.
    If the metric expansion of space applied uniformly at all length scales and to all objects independently of local forces, then yes, atoms would have expanded until they'd lost cohesion and we would not be here to post about it. Happily for us, the forces within an atom "win", as does the gravitational force (where I use force as shorthand for what GR describes) that binds the stars within a galaxy.

    If one views metric expansion as analogous to the stretching of a membrane, the forces that bind atoms and solar systems should be thought of as altering the local properties of the membrane, making those regions stiffer. So, over cosmologically relevant distances, we see metric expansion work its magic, but locally, not so much.
    This is very interesting. It strikes me as an under-discussed and rather subtle point. I am not sure I understand it. If we take electrostatic force, as expressed in Coulomb's Law i.e. F = ke. q1.q2/r² and say F resists the metric expansion of r , that would seem to mean that ke has changed with time. Is that what you are saying or have I misunderstood?
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    Quote Originally Posted by Robbedoes View Post
    Quote Originally Posted by tk421 View Post
    Please do not offer ill-formed opinions in response to questions (even if they're your own!). It muddies the waters and confuses the questioner. Cosmological redshift is not gravitational redshift, your opinions aside. Cosmological redshift is simply due to metric expansion. Gravitational redshift is a separate thing altogether.
    I'm sorry. I've said this before on other fora and I know no one agrees with me.
    How can most redshift be because of metric expansion and other because of gravitation?
    If you've been told you're wrong before, why don't you look it up before you make the same mistake again?

    Try this: https://en.wikipedia.org/wiki/Redshift

    Here you will find a distinction being made between a Doppler red shift, a gravitational red shift and an expansionary red shift.
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    Quote Originally Posted by exchemist View Post
    If you've been told you're wrong before, why don't you look it up before you make the same mistake again?

    Try this: https://en.wikipedia.org/wiki/Redshift

    Here you will find a distinction being made between a Doppler red shift, a gravitational red shift and an expansionary red shift.
    I stay with my beliefs because it has not experimentally been shown...it's theoretical.

    If a photon of frequency υ is emitted radially outward from the surface of a gravitational mass M, then the photon energy observed at a distance from the mass will be observed to be lower, or "red shifted".General Relativity
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    Quote Originally Posted by Robbedoes View Post
    Quote Originally Posted by exchemist View Post
    If you've been told you're wrong before, why don't you look it up before you make the same mistake again?

    Try this: https://en.wikipedia.org/wiki/Redshift

    Here you will find a distinction being made between a Doppler red shift, a gravitational red shift and an expansionary red shift.
    I stay with my beliefs because it has not experimentally been shown...it's theoretical.

    If a photon of frequency υ is emitted radially outward from the surface of a gravitational mass M, then the photon energy observed at a distance from the mass will be observed to be lower, or "red shifted".General Relativity
    Aha, so it's a question of your "beliefs", is it? So you're a crank, in other words. Well, at least now we know.

    Doppler redshift, gravitational shift and expansionary redshift all have observational evidence behind them.
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    Quote Originally Posted by exchemist View Post
    Aha, so it's a question of your "beliefs", is it? So you're a crank, in other words. Well, at least now we know.

    Doppler redshift, gravitational shift and expansionary redshift all have observational evidence behind them.
    Can you show me the observable evidence?

    How do you reply to this?
    If a photon of frequency υ is emitted radially outward from the surface of a gravitational mass M, then the photon energy observed at a distance from the mass will be observed to be lower, or "red shifted".General Relativity
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    Quote Originally Posted by Robbedoes View Post
    How do you reply to this?
    If a photon of frequency υ is emitted radially outward from the surface of a gravitational mass M, then the photon energy observed at a distance from the mass will be observed to be lower, or "red shifted".General Relativity
    How is this relevant to cosmological redshift?
    There are no paradoxes in relativity, just people's misunderstandings of it.
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    Quote Originally Posted by Robbedoes View Post
    What causes cosmological redshift do you think?
    Consider a single oscillation cycle of the electromagnetic field at a source. Then from the start and end of the oscillation cycle, the electromagnetic field will propagate independently at the local speed of light towards a distant receiver. But by the time the propagated electromagnetic field has reached the receiver, the intervening space has expanded so that the paths from the start and end of the oscillation cycle has increased in separation resulting in a greater wavelength.
    There are no paradoxes in relativity, just people's misunderstandings of it.
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    Quote Originally Posted by Robbedoes View Post
    Quote Originally Posted by exchemist View Post
    Aha, so it's a question of your "beliefs", is it? So you're a crank, in other words. Well, at least now we know.

    Doppler redshift, gravitational shift and expansionary redshift all have observational evidence behind them.
    Can you show me the observable evidence?

    How do you reply to this?
    If a photon of frequency υ is emitted radially outward from the surface of a gravitational mass M, then the photon energy observed at a distance from the mass will be observed to be lower, or "red shifted".General Relativity
    And if that same photon then approaches the surface of another gravitational mass, it will "blue-shift". In other words, Light leaving galaxy A would be red-shifted climbing out of its gravitational field, but blue shifted falling into the gravitational field of our galaxy. Any net difference upon observation would be a result of the difference in gravitational potential between observation point and emission point, or the relative depths of the Gravity wells at those points. This could give us a measure of the relative mass of the galaxy, As we would see a net blue-shift from galaxies less massive than our own and a red shift from those more massive than our own, but this would not bear any relationship to the distance between the galaxies as cosmological Redshift does.
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  35. #34  
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    Quote Originally Posted by Robbedoes View Post
    Quote Originally Posted by exchemist View Post
    Aha, so it's a question of your "beliefs", is it? So you're a crank, in other words. Well, at least now we know.

    Doppler redshift, gravitational shift and expansionary redshift all have observational evidence behind them.
    Can you show me the observable evidence?

    How do you reply to this?
    If a photon of frequency υ is emitted radially outward from the surface of a gravitational mass M, then the photon energy observed at a distance from the mass will be observed to be lower, or "red shifted".General Relativity
    No I'm fed up with spoon-feeding cranks. Look it up yourself.

    Start by reading the article I linked to, which describes some of the observations, and then look up anything you think is not exemplified in that article. You will find all 3 types of redshift have observations that illustrate them.

    (Of course, being a crank, you will most likely NOT do this, as it might knock your crank ideas on the head. )
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    Sonce the OP is, apparently, preferring belief and isn't going to listen to science: moved to Personal Theories.
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    Quote Originally Posted by Robbedoes View Post
    Quote Originally Posted by exchemist View Post
    If you've been told you're wrong before, why don't you look it up before you make the same mistake again?

    Try this: https://en.wikipedia.org/wiki/Redshift

    Here you will find a distinction being made between a Doppler red shift, a gravitational red shift and an expansionary red shift.
    I stay with my beliefs because it has not experimentally been shown...it's theoretical.
    It is unfortunate that you think that belief trumps the scientific method. In this case, it appears that you have worked assiduously to avoid the experimental evidence that contradicts your belief. Exchemist was kind enough to point you to the relevant literature. Don't give in to a fear of enlightenment.

    If a photon of frequency υ is emitted radially outward from the surface of a gravitational mass M, then the photon energy observed at a distance from the mass will be observed to be lower, or "red shifted".General Relativity
    You're going to have to learn at least the rudiments of argument. Non sequiturs that address misattributions don't convince. If we had said "gravitational redshift does not exist" then you would have been en pointe, but that wasn't the statement made. What was actually said was that cosmological redshift is distinct from gravitational redshift.

    From what you've said, you've heard this before, yet instead of investigating the evidence, you've simply held to your beliefs. If you're that stubbornly unscientific then I fear that you will have a short tenure here (note name of this forum).
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    Quote Originally Posted by KJW View Post
    Quote Originally Posted by Robbedoes View Post
    How do you reply to this?
    If a photon of frequency υ is emitted radially outward from the surface of a gravitational mass M, then the photon energy observed at a distance from the mass will be observed to be lower, or "red shifted".General Relativity
    How is this relevant to cosmological redshift?
    It explains gravitational redshift which imo causes cosmological redshift. Stars are massive bodies and have gravitational field....
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    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by Robbedoes View Post
    Quote Originally Posted by exchemist View Post
    Aha, so it's a question of your "beliefs", is it? So you're a crank, in other words. Well, at least now we know.

    Doppler redshift, gravitational shift and expansionary redshift all have observational evidence behind them.
    Can you show me the observable evidence?

    How do you reply to this?
    If a photon of frequency υ is emitted radially outward from the surface of a gravitational mass M, then the photon energy observed at a distance from the mass will be observed to be lower, or "red shifted".General Relativity
    No I'm fed up with spoon-feeding cranks. Look it up yourself.

    Start by reading the article I linked to, which describes some of the observations, and then look up anything you think is not exemplified in that article. You will find all 3 types of redshift have observations that illustrate them.

    (Of course, being a crank, you will most likely NOT do this, as it might knock your crank ideas on the head. )
    Yes I'm a crank. I've had this idea for a long time and the more I discuss it and learn about it, the more I get convinced I'm correct. Also gravitational redshift is 'from' Einstein. He would never agree with this opinion that only relative motion lengthens waves. This is because of hi deterministic point of view. Again, Cosmo redshift is due to starlight and stars have a gravitational field. Starlight interacts with the gravitational field...this causes the redshift. Or is general relativity wrong?
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  40. #39  
    exchemist
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    Quote Originally Posted by Robbedoes View Post
    Quote Originally Posted by exchemist View Post

    No I'm fed up with spoon-feeding cranks. Look it up yourself.

    Start by reading the article I linked to, which describes some of the observations, and then look up anything you think is not exemplified in that article. You will find all 3 types of redshift have observations that illustrate them.

    (Of course, being a crank, you will most likely NOT do this, as it might knock your crank ideas on the head. )
    Yes I'm a crank. I've had this idea for a long time and the more I discuss it and learn about it, the more I get convinced I'm correct. Also gravitational redshift is 'from' Einstein. He would never agree with this opinion that only relative motion lengthens waves. This is because of hi deterministic point of view. Again, Cosmo redshift is due to starlight and stars have a gravitational field. Starlight interacts with the gravitational field...this causes the redshift. Or is general relativity wrong?
    Have you looked up those sources as I suggested? If not, don't bother me again until you have.
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    Your Mama! GiantEvil's Avatar
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    Okay, I’m already tired of Robittybob again. Duck and his banhammer please!
    I was some of the mud that got to sit up and look around.
    Lucky me. Lucky mud.
    -Kurt Vonnegut Jr.-
    Cat's Cradle.
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  42. #41  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by GiantEvil View Post
    Okay, I’m already tired of Robittybob again. Duck and his banhammer please!
    Unfortunately the evidence (so far) is that he's not Robittybob.
    "[Dywyddyr] makes a grumpy bastard like me seem like a happy go lucky scamp" - PhDemon
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  43. #42  
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    Well, seeing as robittybobonknob was so stupid that he could easily forget to breath, he’s probably dead now. It’s a miracle that robittyboob could even find the on switch of his computer. Talk about somebody impervious to basic reason. Whoever this newby is, well I guess he’s just another boring crank.
    I was some of the mud that got to sit up and look around.
    Lucky me. Lucky mud.
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  44. #43  
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    Quote Originally Posted by Robbedoes View Post
    Yes I'm a crank. I've had this idea for a long time and the more I discuss it and learn about it, the more I get convinced I'm correct.
    What you have learned? From the statements you've made, it is painfully obvious that you haven't studied very much. (But thanks for the info re: plants.)

    Also gravitational redshift is 'from' Einstein.
    You are overly fond of non-sequiturs. That habit severely undermines what little credibility you have.

    He would never agree with this opinion that only relative motion lengthens waves. This is because of hi deterministic point of view.
    Once again, you're refuting statements that no one here has made. I can't tell if you are incapable of reading, or if you're dishonest. In any case, no one said that ONLY relative motion lengthens waves. What has been said is that redshift can be caused by several sources. But this thread is about cosmological redshift.

    Your invocation of Einstein's determinism is another non-sequitur, buried within an attempt to hide behind Einstein in a weak argumentum ab auctoritate.

    Again, Cosmo redshift is due to starlight
    And again, no.

    and stars have a gravitational field.
    You are overly fond of non-sequiturs.

    Starlight interacts with the gravitational field...this causes the redshift.
    Show quantitatively that the observed redshift can be explained by your mechanism. Since your extensive study has led you to reject the conventional explanation (which, by the way, is from Einstein), one presumes that detailed calculations compelled you to adopt the position that GR is wrong. I eagerly await your maths.

    Or is general relativity wrong?
    Again, a non-sequitur. Your assertions are contrary to those of GR, so the choice is between you and Einstein. So far, ol' Albert's position is much more compelling.
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  45. #44  
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    Quote Originally Posted by Robbedoes View Post
    Or is general relativity wrong?
    No, but your understanding of it is. As I already explained, Just as there is a gravitational red-shift for light climbing out of a gravity well, there is a gravitational blue-shift for light falling into one. If you view a galaxy from deep in intergalactic space, you will see its light red-shifted. But we don't view them from there but from within our own galaxy's and Sun's gravity well, which means that the light will have a been blue-shifted again on it way to us. If we were viewing a star in a galaxy the same size as ours and orbiting at the same distance from the center, then these two effect would cancel out exactly, and we measure neither a red or blue shift in its light.

    Then there is the fact that the GR predicted gravitational red-shift for light leaving a galaxy, even if measured from an infinite distance away, doesn't even come close to the values we measure from distant galaxies. So, the idea that cosmological red-shift can be attributed to gravitational red-shift fails on more than one level.
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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  46. #45  
    Forum Freshman Robbedoes's Avatar
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    When they observe redshift then they don't study the forming of the redshift (because its impossible atm) but they assume which redshift it is due to the source of the radiation….there is no evidence for what causes the cosmological redshift.

    The idea that radiation/quanta change properties only due to motion/expansion of space is not proven in any way. You people think a photon that travels trough vacuum can change energy without it interacts with anything...very odd. This misinterpretation is imo due to the 'random' behavior of quantum particles and due to the 'fact' that gravity can't atm be quantized.

    t is observed by how redshift varies with distance. If there were a direct relationship between Redshift and distance, then this would indicate a constant rate of expansion.
    Who observed this? Which redshift?
    In other words, Light leaving galaxy A would be red-shifted climbing out of its gravitational field, but blue shifted falling into the gravitational field of our galaxy
    Experimental evidence for this?

    There is a lot of theoretical hassle that doesn't prove anything.
    Last edited by Robbedoes; January 30th, 2019 at 10:52 AM. Reason: typo
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  47. #46  
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    Quote Originally Posted by Robbedoes View Post
    In other words, Light leaving galaxy A would be red-shifted climbing out of its gravitational field, but blue shifted falling into the gravitational field of our galaxy
    Experimental evidence for this?
    The Pound-Rebka experiment. They measured the predicted red-shift when the source with the source at the bottom of the tower and the receiver was at the top, and the predicted blue shift when the source was at the top of the tower and the receiver at the bottom.

    It really can't be any other way. If light decreases in frequency climbing away from a gravity source, it has to increase in frequency while falling in. Otherwise you would have a violation of energy conservation. Earlier you referenced General Relativity in connection to gravitational red-shift. But GR also predicts the gravitational blue-shift. It also predicts the cosmological red-shift, but for different reasons. You can't just pick and choose what aspects of the theory you want to accept.
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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  48. #47  
    Bullshit Intolerant PhDemon's Avatar
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    You can't just pick and choose what aspects of the theory you want to accept.
    You've forgotten PhDemon's 1st law: "Never underestimate the mental contortions a crank will allow to avoid admitting they are wrong."
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