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Thread: Halve the Hubble constant! (still apears to be 72km/s/Mpc)

  1. #31
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    IF02 https://en.wikipedia.org/wiki/Friedmann_equations

    IF01 and IF05 matching light curves - which gives luminosity distance and the diagram of distance moduli against redshift.
    https://www.google.co.uk/search?q=di...=1499931142800

    The attempt to match this data in the mainstream lamda CDM model leads to 'evidence' that omega(matter) is about 0.29, bold line. However since they have an extra variable parameter, a match would have been found.

    The new redshift scalefactor relation 1+z = (a(0)/a(1))^2 matches the data without any extra variable parameter, similar diagram is in the pdf and here (red line is from new relation omega(m)=1.0) https://www.desmos.com/calculator/aof8ao1stj
    So 'evidence' from supernovae for 'dark energy' , gives an even better argument to change the redshift-scalefactor relation.

    Planck and WMAP data quote values for e.g. omega(matter)*h^2 = 0.134 from this they deduce that omega(matter) approx. 0.25 and dark energy parameter =0.75. However since they are using a value of h which is double the true value, the 0.25 conclusion is wrong and should be 1.0

    The unlucky mess mainstream cosmologists have got themselves in, is due to two separate methods (supernovae data, and WMAP etc..) giving similar values for omega(m) of 0.25. The advantage of considering the new redshift-scalefactor relation is that both of these pieces of 'evidence' for dark energy, also both support the new relation
    Last edited by john hunter; 2017-Jul-13 at 08:09 AM.

  2. #32
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    Quote Originally Posted by john hunter View Post
    At last you read my post. Which leads to the follow up question:
    IF02a: Do you know that the H in those equations is not Hubble's constant?

    Quote Originally Posted by john hunter View Post
    IF01 and IF05 matching light curves - which gives luminosity distance and the diagram of distance moduli against redshift.
    Still not fully correct (and even worse with a Google search!) but close enough for IF01. Light curves are fitted (not matched) so that their shape, luminosity, and color turn the supernova into standard candles.

    IF05: Show how the diagram you cite is a test of different cosmological models, e.g. list them. is about the specific diagram you cited.

    Quote Originally Posted by john hunter View Post
    The attempt to match this data in the mainstream lamda CDM model leads to 'evidence' ...
    You know that sentence is wrong since you have read the appropriate papers. It is the success in matching the Type 1a supernova data using the mainstream Lambda-CDM model that is the evidence without quotes that omega(matter) is about 0.29.

    Despite what you imagine about plugging in "wrong values", WMAP data gave 4.6% ordinary matter, 24.0% dark matter and 71.4% dark energy and Planck data gave 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy.
    IF06: List the measurements of the Hubble constant being 36 km/s/Mpc.

    There is no "unlucky mess". There is working mainstream cosmology that is supported by several independent lines of evidence. You know something about the first two of these
    1. Type 1a supernova data.
    2. Cosmic microwave background
    3. Large-scale structure
    4. Late-time integrated Sachs-Wolfe effect
    5. Observational Hubble constant data which is measuring the Hubble parameter H(z).
    Last edited by Reality Check; 2017-Jul-13 at 09:20 PM.

  3. #33
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    Quote Originally Posted by Reality Check View Post
    At last you read my post. Which leads to the follow up question:
    IF02a: Do you know that the H in those equations is not Hubble's constant?
    .....
    There is no "unlucky mess". There is working mainstream cosmology that is supported by several independent lines of evidence. You know something about the first two of these
    1. Type 1a supernova data.
    2. Cosmic microwave background
    3. Large-scale structure
    4. Late-time integrated Sachs-Wolfe effect
    5. Observational Hubble constant data which is measuring the Hubble parameter H(z).
    Dark energy versus a(dot)/a being half the mainstream value...

    1) Type 1a Supernovae data: this graph https://www.desmos.com/calculator/aof8ao1stj matches the data with a constant Hubble parameter, no acceleration, omega(matter)=1, with a formula derived from the new redshift-scalefactor relation. Dark energy gets a match too but with an extra variable parameter.

    2) CMB quotes values for e.g. omega(m)h^2 =0.135 and then derives omega(m) to be about 0.25, using a value for h which is double the true value. If the correct value is used omega(m)=1.0

    3) Later…

    4) Late-time integrated Sachs-Wolfe effect:

    A significant paper on the ISW is https://arxiv.org/abs/1209.2125

    However this paper is not independent of the other methods

    On page 5 near the beginning of section 3 they state their assumptions “In the following analysis…we assume a flat lambda CDM cosmology…WMAP7 + BAO + H(0)…Komatsu et al ,2011” they also list a few values but not all, H(0) has to be found from https://arxiv.org/abs/1001.4635 right hand column of table 1, top of page 3. Now we can see that the ISW analysis has assumed H(0)=70.2 and omega(m)h^2 =0.1352 i.e an assumption for omega(m)=0.274 has been put in at the beginning, (and flatness, total=1) so they find ‘evidence’ for dark energy, what a surprise!

    5) Later…
    Last edited by john hunter; 2017-Jul-14 at 10:14 AM.

  4. #34
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    5. Observational Hubble constant data which is measuring the Hubble parameter H(z).

    this paper https://arxiv.org/abs/1507.02517 has a table (page 2) which list z and H(z). They then have a graph (page 3) which shows H(z) increasing and a that predicted by lambda CDM. The match isn't great.

    The observations are of a quantity dz/dt from which H(z) is worked out from (-1/(1+z))*dz/dt. This uses the mainstream scalefactor-redshift relation.

    With the new redshift-scalefactor relation H(z) = (-1/2(1+z))*dz/dt, so the data can be interpreted to show a quantity 2H(z).

    A universe with constant rate of expansion would have a straight line on the diagram, (thanks to Q & A section) of the form H(z)=H(0)(1+z) , which fits the data very well, with H(0) of about 64, so this data can be interpreted as support for a constant rate of expansion with 2(a(dot)/a) = 64 and a(dot)/a = 32km/s/Mpc

    (The H(z) data divided by 1+z is
    64.4, 63.3, 61.25, 70.9, 63.6
    62.6, 60.8, 64.3, 60.6, 69.4
    60.8, 62.5, 61.4, 67.9, 60.5
    57.4, 65.5, 58.9, 65.3, 54.9
    54.7, 56.2, 59.0, 66.7, 47.9
    61.6, 75.6, 73.0, 67.7, 72.8
    55.3, 73.5, 62.9, 67.9, 66.5, 67.3)

  5. #35
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    Quote Originally Posted by john hunter View Post
    Dark energy versus a(dot)/a being half the mainstream value...
    1) is irreverent which you should know because you have read Riess 1998 and Perlmutter 1998.
    The entire point of these papers is that the curves with non-zero cosmological constant fit the data better than curves with zero cosmological constant.
    A single curve that goes through the data points is useless. We know that such a curve can be drawn for a dark energy less universe. The prospect of a better fit to more data is why Riess 1998 and Perlmutter 1998 were written.

    2) Repeating an unsupported assertion does not make it true.

    4) The Late-time integrated Sachs-Wolfe effect is still evidence for dark energy.
    The significance of the integrated Sachs-Wolfe effect revisited (2012) is confirmation of previous results.
    The universe tells us that it is
    1. Flat
    2. Has dark matter (CDM)
    3. Can have a non-zero cosmological constant (lambda).

    The authors start with "a flat lambda CDM cosmology" where the cosmological constant can have any value. They use the integrated Sachs-Wolfe effect to measure the cosmological constant. They find that the value is not zero.
    Last edited by Reality Check; 2017-Jul-16 at 11:13 PM.

  6. #36
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    Quote Originally Posted by john hunter View Post
    5. Observational Hubble constant data which is measuring the Hubble parameter H(z).
    5) Citing a preprint Utility of observational Hubble parameter data on dark energy evolution is not support for lambda = 0.
    This is a seemingly unpublished preprint from 2015. The authors state in the abstract "we cannot rule out the validity of ΛCDM".

  7. #37
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    Quote Originally Posted by john hunter View Post
    this paper https://arxiv.org/abs/1507.02517 has a table (page 2) which list z and H(z).
    Read the table that you cite, john hunter. Those are measured values of H(z). Those measured values of h(z) are all above 68.6. They blow your claim that H(z) or H0 is half the measured value (36) out of the water 36 times !
    That is the thing about measurements. It is ridiculous to state that a measurement is half what it is measured to be without any evidence. Think about the measured distance from Earth to the Moon. What would you think about someone stating that the distance to the Moon is half what is measured? I hope that you would demand evidence for that assertion. You should be able to think up numerous other examples. Is it valid to assert that someone's height is half what is measured? What about the length of a football field? The mass of an electron? Thus what about the measured value of H0 or H(z)?

  8. #38
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    OK, assuming that your scale factor/redshift relationship is correct for a moment (there seems to be no evidence or justification for it so I will take it as a postulate). How do you account for the observed time dilation of distant supernovae? This is a probe of the recessional velocity that supports the current value of H0 as well. And something we can test in the laboratory. So why would extragalatic things obey a different form of GR than local objects?

  9. #39
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    Quote Originally Posted by Reality Check View Post
    1) is irreverent which you should know because you have read Riess 1998 and Perlmutter 1998.
    The entire point of these papers is that the curves with non-zero cosmological constant fit the data better than curves with zero cosmological constant.
    A single curve that goes through the data points is useless. We know that such a curve can be drawn for a dark energy less universe. The prospect of a better fit to more data is why Riess 1998 and Perlmutter 1998 were written.
    Someone needs to be irreverent, to bring todays cosmologists/physicists down to earth! (dark energy! Can you imagine bringing it as a new idea and trying to defend it on ATM)...or did you mean irrelevant?

    Quote "the curves with non-zero cosmological constant fit the data better than curves with zero cosmological constant" is probably true, but only using the usual and incorrect redshift-scalefactor relation. The match to data is just as good, with zero cosmological constant (and fewer variable parameters) when the correct redshift-scalefactor relation is used.
    So this graph https://www.desmos.com/calculator/aof8ao1stj remains an important piece of evidence in support of the new relation.
    Last edited by john hunter; 2017-Jul-17 at 07:23 AM.

  10. #40
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    Reality Check,

    regarding the rest of your post 35 on the ISW, the assumptions they have used and put into their model were mentioned in post 33, namely "H(0)=70.2 and omega(m)h^2 =0.1352 i.e an assumption for omega(m)=0.274 has been put in at the beginning, (and flatness, total=1), so any 'evidence' for dark energy from this type of study is not valid.

    re: post 37 Just to keep referring to the use of the term "Hubble constant" or "measurement" is not an argument against the main purpose of the OP. Which was quote "a change to the usual scalefactor-redshift relation, which can remove the main arguments for an accelerating universe..." which leads to the rate of expansion a(dot)/a being half the mainstream accepted value.

    Your colleague Shaula explained in a recent Q&A thread that a straight line on the H(z) vs z diagram would be evidence for a constant rate of expansion. so the graph, page 3 of https://arxiv.org/abs/1507.02517 (which can be well fitted with a straight line H(0)(1+z) with H(0) about 64 or 66 can be regarded as evidence for a constant rate of expansion a(dot)/a of half the usually accepted value.

    In the Q&A thread... https://forum.cosmoquest.org/showthr...-H(z)-measured ...post 9, Shaula mentioned that the LCDM gave a better fit, but said the data was consistent with both models. Since LCDM has more variable parameters to obtain the fit, the support for constant a(dot)/a is good, since only H(0) can vary.

    Shaula... re: time dilation. Since any measurement at redshift z has light stretched by factor (1+z), in both models there would be the time dilation of supernovae etc... The new redshift-scalefactor relation is not meant to be an argument against the expanding universe, or against Big Bang. Just that the rate of expansion is half and that it is constant.
    Last edited by john hunter; 2017-Jul-17 at 08:07 AM.

  11. #41
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    Quote Originally Posted by john hunter View Post
    Shaula... re: time dilation. Since any measurement at redshift z has light stretched by factor (1+z), in both models there would be the time dilation of supernovae etc... The new redshift-scalefactor relation is not meant to be an argument against the expanding universe, or against Big Bang. Just that the rate of expansion is half and that it is constant.
    My point was that redshift is defined as a ratio of frequencies. Your argument appears to be that this ratio of frequencies is related to the scale factor and the Hubble constant is a quadratic rather than linear way. My question is why time dilation, which is an independent check on this, apparently supports the higher recessional velocity. I am trying to work out if you have any ideas on why this relationship might be quadratic, what you believe it affects and so on. Because we see and measure redshift and time dilation in the lab and we would have noticed a factor of two difference.

    So, for example, if we were to take the rotation of galaxies. Would you expect the differential redshift between each side of a rotating disk to also show this kind of quadratic dependence on velocity?

    At the moment you seem to be saying that if we adopt your relationship only as and when you say so it gives good results - which seems a little ad hoc to me.

  12. #42
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    Quote Originally Posted by Shaula View Post
    My point was that redshift is defined as a ratio of frequencies. Your argument appears to be that this ratio of frequencies is related to the scale factor and the Hubble constant is a quadratic rather than linear way. My question is why time dilation, which is an independent check on this, apparently supports the higher recessional velocity. I am trying to work out if you have any ideas on why this relationship might be quadratic, what you believe it affects and so on. Because we see and measure redshift and time dilation in the lab and we would have noticed a factor of two difference.

    So, for example, if we were to take the rotation of galaxies. Would you expect the differential redshift between each side of a rotating disk to also show this kind of quadratic dependence on velocity?
    There are a few things here.

    a) Firstly the redshift due to expansion of the universe isn't really due to a Doppler shift 'velocity', although it is often described that way. The new relation is that 1+z = f(1)/f(0) = (a(0)/a(1))^2 (where the 1 stands for a quantity at time of emission from a distant source and the 0 is for arrival.)

    b)The rotation of a galaxy would produce the normal Doppler shift and for that df/f=v/c where df is a change in frequency, v is the velocity of the edge of the galaxy...

    The reason for the different treatments a) and b) is that one is due to the cosmological expansion, change of scale-factor of the universe, but the other isn't.

    Time dilation from a distant source of redshift z would be by a factor (1+z), as the time taken for each wavelength to arrive is lambda/c and lambda has increased by the factor (1+z)

    About the factor 2, not sure exactly what you meant, but since, in the theory, the rate of expansion a(dot)/a is half the mainstream value (abbreviation H),
    then 1+z = [(a(1)+da)/a(1)]^2 = (1+Hdt)^2 = 1+2Hdt +(Hdt)^2. since the last term is negligible z=2Hdt so v/c = 2Hdt and v=2Hcdt and v=2Hd, where d is the distance to the source, this is equivalent to the usual Hubble law since H is half the mainstream value i.e. H(0)=2H, so v=H(0)d, and the difference could not easily be noticed.

  13. #43
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    Quote Originally Posted by john hunter View Post
    Someone needs to be irreverent,....
    Irrelevancy is always a waste of not only your time but the time of other posters. If dark energy did not exist and someone were to present it as an "ATM" idea with the same evidence as in Riess 1998 and Perlmutter 1998 then it would be accepted immediately. It would be quite simple - the standard, mainstream cosmology model fit the data better with a non-zero cosmological constant, thus dark energy!

    The curves with non-zero cosmological constant fit the data better than curves with zero cosmological constant is a fact. Read Riess 1998 and Perlmutter 1998 again and the full analysis in the papers. They do not plot a single curve and say it fits the data. They do not plot curves and assert that the ones with dark energy fit the data better. They calculate the residuals between the curves and the data. The curve with the lowest residuals is fits the data better. This is science covered in first year physics courses and even a bit at high school level.

    A fantasy of "The match to data is just as good" is just that until you do the same analysis. There is even a suggestion that your curve is false. You arbitrarily halve the Hubble constant to have a value that it is not measured to have. That will halve the slope of your curve at low z (this is Hubble's law). That cannot fit the supernova data which has a slope of H0 ~ 72 at low z !
    IF06: List the measurements of the Hubble constant being 36 km/s/Mpc.
    IF08: Show the slope of your curve at low z (it has to be ~72 to fit the supernova data).

  14. #44
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    Quote Originally Posted by john hunter View Post
    regarding the rest of your post 35 on the ISW, the assumptions they have used
    I read and replied to your post already. One more time: They plug in the measured values for H0 (not H(0)) and omega(m)h^2 and see if the cosmological constant is nonzero by fitting the data.

    A fact that you keep denying: The Hubble constant is a measurement and as I wrote:
    Quote Originally Posted by Reality Check View Post
    That is the thing about measurements. It is ridiculous to state that a measurement is half what it is measured to be without any evidence. Think about the measured distance from Earth to the Moon. What would you think about someone stating that the distance to the Moon is half what is measured? I hope that you would demand evidence for that assertion. You should be able to think up numerous other examples. Is it valid to assert that someone's height is half what is measured? What about the length of a football field? The mass of an electron? Thus what about the measured value of H0 or H(z)?
    So I will make tis a formal question:
    IF09: Is it valid to halve the measured distance From the Earth to Moon?

    Shaula was incorrect as you should have pointed out! As a proposer of an ATM idea you should know the mainstream that you are arguing against. What is worse you have known about the Wikipedia Hubble's law article for at least a few days.
    Hubble's law is the name for the observation in physical cosmology that:
    1.Objects observed in deep space (extragalactic space, 10 megaparsecs (Mpc) or more) are found to have a Doppler shift interpretable as relative velocity away from Earth;
    2.This Doppler-shift-measured velocity, of various galaxies receding from the Earth, is approximately proportional to their distance from the Earth for galaxies up to a few hundred megaparsecs away.[1][2]
    FYI: that "few hundred megaparsecs" is a redshift of z < 0.1 which is the Hamuy et al, 1996 data plotted in Reiss et. al. (1998) Fig 2 where the curves and data are approximately a straight line.
    Read the Wikipedia Hubble's law article, Derivation of the Hubble parameter section. Note that H(z) is not a straight line without dark energy except at low z (z << 1).

    Another source: Ned Wright's Cosmology Tutorial and note the approximation used to relate redshift and velocity:
    Hubble's data in 1929 is actually quite poor, since individual galaxies have peculiar velocities of several hundred km/sec, and Hubble's data only went out to 1200 km/sec. This has led some people to propose quadratic redshift-distance laws, but the data shown below on Type Ia SNe from Riess, Press and Kirshner (1996)
    [his figure]
    extend beyond 30,000 km/sec and provide a dramatic confirmation of the Hubble law, v = dD/dt = H*D

    The fitted line in this graph has a slope of 64 km/sec/Mpc. Since we measure the radial velocity using the Doppler shift, it is often called the redshift. The redshift z is defined such that: 1 + z = lambda(observed)/lambda(emitted)
    where lambda is the wavelength of a line or feature in the spectrum of an object. In special relativity we know that the redshift is given by 1 + z = sqrt((1+v/c)/(1-v/c)) so v = cz + ...
    but the higher order corrections (the "...") in cosmology depend on general relativity and the specific model of the Universe.

  15. #45
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    Quote Originally Posted by john hunter View Post
    so the graph, page 3 of https://arxiv.org/abs/1507.02517 (which can be well fitted with a straight line H(0)(1+z).
    The curve cannot be fitted with an arbitrary equation pulled out of thin air. The curve especially cannot be fitted with an unsupported assertion of a straight line! The point of that unpublished preprint is that the authors think that the H(z) as in their equation 3 (which is not a straight line) fit to the data is not as good as previous, published papers have stated.

  16. #46
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    Quote Originally Posted by john hunter View Post
    ...but since, in the theory, the rate of expansion a(dot)/a is half the mainstream value (abbreviation H),
    The rate of expansion is not a(dot)/a. It is the dimensionless Hubble parameter that is defined as a(dot)/a. And once again the Hubble parameter is a function that is not the Hubble constant. The usual notation for the Hubble constant is H0 not H.
    Quote Originally Posted by john hunter View Post
    then 1+z = [(a(1)+da)/a(1)]^2
    Unfortunately looks like nonsense with that a(1). There is a relationship between the scale factor at the time light is emitted from an object and its redshift: a(t) = 1/(1+z).

  17. #47
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    Quote Originally Posted by Reality Check View Post
    The curves with non-zero cosmological constant fit the data better than curves with zero cosmological constant is a fact. Read Riess 1998 and Perlmutter 1998 again and the full analysis in the papers. They do not plot a single curve and say it fits the data. They do not plot curves and assert that the ones with dark energy fit the data better. They calculate the residuals between the curves and the data. The curve with the lowest residuals is fits the data better....
    Yes, that's right, but the curve which has the best match (i.e for which the extra variable parameter gives the best match) is chosen. That's not good evidence that the model is correct as a match is almost bound to be found. It can be argued that because the curves match the data only with a non-zero cosmological constant, it's an indication that something is wrong with mainstream understanding...The strength of the new proposal is that there is only one variable parameter.

    Quote Originally Posted by Reality Check View Post
    There is even a suggestion that your curve is false. ).
    You don't say who by. Please show them the pdf with the appendix which works out the formula D=2c/H(1+z)[sqrt(1+z)-1]...then show them this https://www.desmos.com/calculator/aof8ao1stj and mention that by clicking on the tab near the top left all the data is shown for 186 points from the High-Z team. At the bottom of the data is the formula for the red line which is the same as that above, put into DM =25 +5 log(D) They might notice the number 70 on the denominator...

    Another quote from you
    "Halving H(0) will halve the slope of your curve at low z (this is Hubble's law). That cannot fit the supernova data which has a slope of H0 ~ 72 at low z !"

    But the curve does fit the data.

    Above the 70 is 600000 which is 2c in km/s...i.e the start of the formula is c/(H(0)/2). The curve fits the data with an a(dot)/a value of half the mainstream, if you like it or not. There is just a different theory... perhaps you should look at the end section of the post above yours, number 42.

    The least the moderators could do is not question proper data when it is presented, it's what they usually ask for.

  18. #48
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    Quote Originally Posted by john hunter View Post
    Yes, that's right, but the curve which has the best match (i.e for which the extra variable parameter gives the best match) is chosen. That's not good evidence that the model is correct as a match is almost bound to be found.
    You still do not understand. There is no "extra variable parameter". A cosmological constant has always been in GR. It was assumed to be zero for a long time because there was no evidence for it being non-zero. It is the curve that best fits the data that is correct as a match. That curve has a non-zero cosmological constant.

    I suggest that your curve is false. The real data has a slope of H0 = 72 at low z. You cannot match that slope with half of H0. You also cannot arbitrarily halve a measurement.
    IF06: List the measurements of the Hubble constant being 36 km/s/Mpc.
    IF08: Show the slope of your curve at low z (it has to be ~72 to fit the supernova data).
    IF09: Is it valid to halve the measured distance From the Earth to Moon (H0 is a measured value like that length)?

    And the next question. Why is dividing a measured value by 2 any more valid than dividing it by any other value (what about pi ). Thus:
    IF10: What happens to your fit to the data if you divide H0 by 10 or multiply it by 10?

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    Quote Originally Posted by john hunter View Post
    a) Firstly the redshift due to expansion of the universe isn't really due to a Doppler shift 'velocity', although it is often described that way. The new relation is that 1+z = f(1)/f(0) = (a(0)/a(1))^2 (where the 1 stands for a quantity at time of emission from a distant source and the 0 is for arrival.)
    Yeah, sorry, I do know that. Looking at my posts that is not obvious from how I phrased things and it does look like I need a Cosmology 101!

    Quote Originally Posted by john hunter View Post
    b)The rotation of a galaxy would produce the normal Doppler shift and for that df/f=v/c where df is a change in frequency, v is the velocity of the edge of the galaxy...
    Right, so your effect is only linked to metric expansion and not an attempt to change any of the underlying GR. That was what I was, clumsily, trying to get to. Mainly as a simple way to work out what we can and cannot test relating to it. Looks like we can't test anything locally.

    Quote Originally Posted by john hunter View Post
    About the factor 2, not sure exactly what you meant, but since, in the theory, the rate of expansion a(dot)/a is half the mainstream value (abbreviation H),
    then 1+z = [(a(1)+da)/a(1)]^2 = (1+Hdt)^2 = 1+2Hdt +(Hdt)^2. since the last term is negligible z=2Hdt so v/c = 2Hdt and v=2Hcdt and v=2Hd, where d is the distance to the source, this is equivalent to the usual Hubble law since H is half the mainstream value i.e. H(0)=2H, so v=H(0)d, and the difference could not easily be noticed.
    So next question is about the statement that the quadratic term is negligible. Is this because you are using infinitesimals? Does this mean that you can only use your form if you treat it as a path integral problem? For example if I swap dt for delta-t and work it out for, say, the Andromeda galaxy then Hdt is much greater than one and the quadratic term is not negligible.

  20. #50
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    Reality Check,

    If you are suggesting that either the data or curve in the graph for the new relation has been falsified - i.e. made up or tampered with, so as to mislead…then an official complaint will be made to CosmoQuest about the moderation of this thread.

    Re: posts 43—46 and 48
    IF08: The slope of the graph and line is 70km/s/Mpc - it matches the data, slope =2H (defined below) , on the full data graph posted previously.

    Here is the low z part, line of best fit as done by Desmos

    https://www.desmos.com/calculator/c7nnitv3da it matches (best) with 2H = 65.95km/s/Mpc. All this can be seen by looking at the data on the left and the formula at the bottom.


    It has been made clear early on (from post 7, and repeated) that the term Hubble constant referred to the rate of expansion a(dot)/a. If you are still complaining about the use of the term ‘Hubble constant’ to refer to the rate of the expansion of the universe, you are missing the bigger picture. However it’s clarified below.

    -------------------------

    What’s happening here can be illustrated with an example similar to your IF09

    IF09: Is it valid to halve the measured distance From the Earth to Moon (H0 is a measured value like that length)?

    Imagine a hypothetical civilisation which wanted to measure the distance to the moon. They measured using Lunar Laser Ranging a quantity called M ‘Moon Time’, which was meant to be the time taken for light to go from the earth to the moon.

    They know that the distance should be D=Mc. For years they measure M and refine their measurements, publish books and papers which contain M and dictionaries which define M. Usually it’s defined as the ratio in the equation i.e. M=D/c but people think of it as the time taken for light to go from the earth to the moon.

    Then one day they realise there has been a big mistake. They have timed from the moment the laser left the earth to the moment it returned.

    Oh no! What should they do.

    Do they decide that M should be halved? In which case M is then the real (one way) time for light to reach the moon? Or do they say that M is a measured quantity and since it has been measured to have a value it cannot be halved?

    Tricky?! It’s a matter of opinion.

    ----------------------------

    But to avoid confusion:
    https://forum.cosmoquest.org/showthr...posting-in-ATM no.13
    “for symbols…define new symbols you may be using.”

    From now on the symbol H stands for a(dot)/a , which, in this ATM idea, is constant. It is now postulated to be a fundamental constant of physics of value approx 1*10^-18 s-1
    Last edited by john hunter; 2017-Jul-18 at 02:32 PM.

  21. #51
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    Quote Originally Posted by Shaula View Post
    So next question is about the statement that the quadratic term is negligible. Is this because you are using infinitesimals? Does this mean that you can only use your form if you treat it as a path integral problem? For example if I swap dt for delta-t and work it out for, say, the Andromeda galaxy then Hdt is much greater than one and the quadratic term is not negligible.
    H as defined in the previous post a(dot)/a is approx. 1*10^-18 . The Andromeda galaxy is about 2.5 million light years away so dt is about 2.537 million years which is t=8*10^13 seconds so Hdt is approx. 8*10^-5, still small.

    However the purpose of the (1+Hdt)^2 approx. = 1+2Hdt comment was just to show that the new relation matches Hubble law for 'small' distances. Both the Hubble law and v=2Hcdt formula are not meant to be accurate if d is large.
    Last edited by john hunter; 2017-Jul-18 at 11:23 AM.

  22. #52
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    Quote Originally Posted by john hunter View Post
    If you are suggesting that either the data or curve in the graph for the new relation has been falsified - i.e. made up or tampered with, so as to mislead…then an official complaint will be made to CosmoQuest about the moderation of this thread.
    If you have a complaint about how this thread is moderated, then make through the appropriate channels: report the post(s) you think is a problem or start a more general discussion in the feedback forum. You do not complain about it in thread and you certainly do not threaten another member with reports. You've been a member here since 2005. It's about time you got a handle on our rules.
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  23. #53
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    Quote Originally Posted by Reality Check View Post
    IF04: Cite the scientific literature that states that the Hubble parameter H has dimensions of seconds^(-1).
    https://en.wikipedia.org/wiki/Friedmann_equations Just under the section 'Equations' there are two equations and to make the top one have consistent dimensions, it can be seen that the Hubble parameter H has dimensions of seconds^-1.

    You probably meant h (the reduced Hubble parameter) when you claimed the Hubble parameter was dimensionless. They are two different things.
    Capital H =a(dot)/a , is the Hubble parameter (defined a couple of lines below the equations) and has dimensions of seconds^-1
    Last edited by john hunter; 2017-Jul-18 at 07:33 PM.

  24. #54
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    I think my irony meter just broke. Well something did anyway.

    CJSF
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    And when a theory emerges
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    -They Might Be Giants, "Science Is Real"


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  25. #55
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    Quote Originally Posted by CJSF View Post
    I think my irony meter just broke. Well something did anyway.

    CJSF
    Please do not make sarcastic comments in this thread, and please confine ourselves to asking the OP questions.
    At night the stars put on a show for free (Carole King)

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  26. #56
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    Quote Originally Posted by john hunter View Post
    IF09: Is it valid to halve the measured distance From the Earth to Moon (H0 is a measured value like that length)?

    Imagine a hypothetical civilisation which wanted to measure the distance to the moon. They measured using Lunar Laser Ranging a quantity called M ‘Moon Time’, which was meant to be the time taken for light to go from the earth to the moon.

    They know that the distance should be D=Mc. For years they measure M and refine their measurements, publish books and papers which contain M and dictionaries which define M. Usually it’s defined as the ratio in the equation i.e. M=D/c but people think of it as the time taken for light to go from the earth to the moon.

    Then one day they realise there has been a big mistake. They have timed from the moment the laser left the earth to the moment it returned.

    Oh no! What should they do.

    Do they decide that M should be halved? In which case M is then the real (one way) time for light to reach the moon? Or do they say that M is a measured quantity and since it has been measured to have a value it cannot be halved?

    Tricky?! It’s a matter of opinion.

    ----------------------------
    The point you seem to be missing is that measurements can be made of both recessional velocity (via Doppler shift) and distance (via Cepheid period-luminosity relationship) in the local universe and the ratio gives H_0. When that is done H_0 is measured to be around 72 km/s/Mpc. For you to say that H_0 should be half that value requires there to have been an error in either the redshift (which would be hard to get wrong), the Cepheid period-luminosity relationship (which has been well established), or the inverse square law that relates luminosity to flux. Which one of these is wrong?

    Your analogy isn't quite right. It's more like this: You measured the distance from one point to another by counting the number of strides it took to walk there and then measuring a single stride. Then if someone comes along and says your distance should actually be half that, you'd be perplexed because you don't think you counted wrong and you know you measured your strides correctly.

    H_0 being around 72 km/s/Mpc is a *measured* quantity, not a theoretically derived one. That's one of the main things that the Hubble Space Telescope was built to do.

  27. #57
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    Better Notation

    There is an interesting article on the cosmological scale factor here:

    https://en.wikipedia.org/wiki/Scale_factor_(cosmology)
    I'm not a hardnosed mainstreamer; I just like the observations, theories, predictions, and results to match.

    "Mainstream isnít a faith system. It is a verified body of work that must be taken into account if you wish to add to that body of work, or if you want to change the conclusions of that body of work." - korjik

  28. #58
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    Quote Originally Posted by Amber Robot View Post
    ...measurements can be made of both recessional velocity (via Doppler shift) and distance (via Cepheid period-luminosity relationship) in the local universe and the ratio gives H_0. When that is done H_0 is measured to be around 72 km/s/Mpc. For you to say that H_0 should be half that value requires there to have been an error in either the redshift (which would be hard to get wrong), the Cepheid period-luminosity relationship (which has been well established), or the inverse square law that relates luminosity to flux. Which one of these is wrong?

    Your analogy isn't quite right. It's more like this: You measured the distance from one point to another by counting the number of strides it took to walk there and then measuring a single stride. Then if someone comes along and says your distance should actually be half that
    This ATM thread is about the possibility that the rate of expansion a(dot)/a is half that accepted by the mainstream.

    1) Both the v (via redshift) and the d have been measured correctly. Astronomers and cosmologists have done a fantastic job over many years to get all this great data which enables us to even discuss this. However the idea developed (in about 1930) that the constant relating the two in v=H(0)d is the same thing as the rate of expansion a(dot)/a. In the ATM proposal it's not the case...v=2Hd and it's this H which is a(dot)/a

    2) The distance doesn't get halved, just the a(dot)a...it leads to a slight change to the luminosity distance-redshift relation which becomes
    D=c/H*[sqrt(1+z)-1] instead of c/H(0)*z. Since H is half of H(0), we can compare z (1st column) against 2[sqrt(1+z)-1]
    0.01---0.00975
    0.05---0.0494
    0.1----0.0976 2.4 % difference
    0.2----0.191
    0.3----0.280
    0.4----0.366
    0.5----0.449 10% difference
    this change means the supernovae distance modulus against redshift data can be matched with constant H and zero cosmological constant.
    Last edited by john hunter; 2017-Jul-19 at 08:15 AM.

  29. #59
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    John Mendenhall,

    Yes, interesting article and your "I'm not a hardnosed mainstreamer; I just like the observations, theories, predictions, and results to match"

    Here are predictions from the new model.
    1) Measurements of omega(matter) will be inferred to be 0.25 (really 1.0)
    2) The Distance modulus-redshift relation will be 25 +5log[(c/H)*(1+z)*(sqrt(1+z)-1)] with H half of Hubbles constant
    3) The graph of H(z) against z will be a straight line of form 2H(1+z)

    If these match observations then the solution to the Friedmann equations. https://en.wikipedia.org/wiki/Friedmann_equations would appear to be
    lamda =0, k=0, H constant,
    G=3H^2/(8*pi*rho) (giving an apparent density parameter of 0.25, really 1.0) and
    p=-rho*c^2

    since H is constant, the interpretation must be that gravity and the value of G are caused by the changing scale factor, but gravity doesn't change the rate of change of scale factor.

    Here is one from Einstein "Everything should be made as simple as possible, but not simpler".
    Last edited by john hunter; 2017-Jul-19 at 01:19 PM.

  30. #60
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    Quote Originally Posted by john hunter View Post
    If you are suggesting that either the data or curve in the graph for the new relation has been falsified - i.e. made up or tampered with, so as to mislead…...
    I stated the obvious. A curve that you state (the title of this thread and several posts) has half the slope of the data cannot fit the data. The measured value of the Hubble constant is the slope of the Hubble diagram:
    Hubble's law can be easily depicted in a "Hubble Diagram" in which the velocity (assumed approximately proportional to the redshift) of an object is plotted with respect to its distance from the observer. A straight line of positive slope on this diagram is the visual depiction of Hubble's law
    A curve with half the slope cannot fit the data. But then you imply that you have not halved the Hubble constant! The Hubble constant is H0. You replace it with a symbol of "2H" where H is some imaginary constant. It is definitely not Hubble's constant which is defined as the slope of the velocity versus distance data.

    You get the definition of the Hubble constant wrong again. it is the Hubble parameter that is defined as a(dot)/a. They Hubble constant is dimensionless as you know and have acknowledged. If you want to create a new symbol for your personal use then it is not the Hubble parameter and you cannot use H.

    I have highlighted the important word that you neglected in IF09. A reason that I used that distance is that a lot of spacecraft have gone to the Moon. Oddly none of them got there in half the expected time! All of them got to a Moon that is at the measured distance from the Earth. And that distance is measured to a very good accuracy because of the laser reflectors left by Apollo. We use the extremely well measured speed of light.So the distance to the Moon is the time the laser light takes to go from the Earth to the Moon divided by 2, times c.

    IF06: List the measurements of the Hubble constant being 36 km/s/Mpc.
    IF08: Show the slope of your curve at low z (it has to be ~72 to fit the supernova data).
    IF09: Is it valid to halve the measured distance From the Earth to Moon (H0 is a measured value like that length)?
    IF10: What happens to your fit to the data if you divide H0 by 10 or multiply it by 10?

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