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Author: rloldershawrloldershaw
Date: Dec 31, 2006 10:14
Richard Saam wrote:
> Kent Paul Dolan wrote:
>> Oh No wrote:
>> No "changed plank scale" or any other voodoo.
J. E. McClintock, et al, in vol. 652 of the Astrophysical Journal,
pages 518-539, 2006, dervive the following relationship for a
Kerr-Newman black hole.
J = aGM^2/c
where J is the angular momentum, a is dimensionless spin, G is the
Newtonian gravitational "constant", M is the mass and c is c.
So here is a little consistency check on the Revised Planck Scale
hypothesis, which is the theme of this thread. Take the proton as a
test case, with J = h(bar), a = 1/2, and, most importantly, with G(n-1)
= 2.18 x 10^31 cgs instead of G. Solve for m(proton) to see if G(n-1)
gives a reasonable result.
When you do the math, you get m(proton) = 1.70 x 10^-24 g.
Unless I have made one of my classic math errors, that agrees with the
empirically measured value of m(proton) at the 98.3%% level.
Not bad for "voodoo".
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Author: ChalkyChalky
Date: Dec 23, 2006 01:17
Phillip Helbig---remove CLOTHES to reply wrote:
> In article hercules.herts.ac.uk>, "Chalky"
> bleachboys.co.uk> writes:
>>>>>One final point. It is clear that astronomers plot deviations of
>>>>distance modulus...
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Author: Oh NoOh No
Date: Dec 22, 2006 13:37
Thus spake Phillip Helbig---remove CLOTHES to reply
LOTHESvax.de>
>In article hercules.herts.ac.uk>, "Chalky"
>bleachboys.co.uk> writes:
>>>>>One final point. It is clear that astronomers plot deviations of
>>>>distance modulus from the distance modulus that would be expected if q
>>>>was always zero, as a function of z. But how do they decide on what
>>>>that expected distance modulus would be?
>>>
>>> They use a cosmological model. In the case of standard models they solve
>>> Friedmann's equation and adjust cosmological parameters to find the best
>>> fit curve.
>>
>> This is nonsense. John is asking you what the flat green line (empty
>> model) is in the exact middle of
>> http://www.astro.ucla.edu/~wright/sne_cosmology.html.
>>
>> You are not answering his question. You are instead insisting on
>> talking about something else that we already know about (the various ...
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Author: Oh NoOh No
Date: Dec 21, 2006 13:07
Thus spake "John (Liberty) Bell" accelerators.co.uk>
>> m - M = 5 log_10(d/10pc)
>
>>From this I conclude the distance modulus has the same 1 + z dependency
>as the luminosity distance. Is that correct?
Not really; the distance modulus is a log law of luminosity distance, so
where luminosity contains a product, distance modulus has a sum.
>I repeat I am pretending
>here for convenience that z is entirely due to peculiar motion in an
>approximately flat volume of spacetime, in order to keep the distance
>and z dependencies of luminosity and magnitude separate at this stage.
That has no bearing on the behaviour of logarithms.
>
>> You can easily check that the dependency on the luminosity and magnitude
>> of the sun drops out from the distant modulus.
>>
>> Now, of course...
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Author: ChalkyChalky
Date: Dec 21, 2006 11:04
Oh No wrote:
> However, normally to
> define a velocity you need first to define a coordinate system. When you
> define a velocity (or indeed any vector) in curved space
I don't see how that is relevant. You have already agreed that space is
flat.
> you only do so
> at a point, because there is no unique way of translating vectors in
> curved space. So to define a velocity which applies to remote points in
> a curved space makes no sense, no matter what communication is taking
> place.
What doesn't make sense is you changing your mind about whether space
is curved or flat. Which is it going to be?
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Author: John (Liberty) BellJohn (Liberty) Bell
Date: Dec 21, 2006 11:03
Oh No wrote:
> Thus spake "John (Liberty) Bell" accelerators.co.uk>>>Phillip Helbig---remove CLOTHES to reply wrote:
>>
>>> In article hercules.herts.ac.uk>, "Chalky"
>>>
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Author: John (Liberty) BellJohn (Liberty) Bell
Date: Dec 21, 2006 01:47
Phillip Helbig---remove CLOTHES to reply wrote:
> In article hercules.herts.ac.uk>, "Chalky"
> bleachboys.co.uk> writes:
>>> This is slightly different to
>> http://www.astro.ucla.edu/~wright/CosmoCalc.html, but both confirm that
>> luminosity distance is not quite what I thought it was. Clearly, from
>> these figures, astronomers do not bother to adjust for the reduction of
>> magnitude resultant on recession velocity (as opposed to distance),
>> before calculating luminosity distance. >
> This implies that it is somehow wrong "not to bother".
Not necessarily, but it does make it more difficult to get a physically
meaningful idea of distance from such a measure, however that distance
is going to be defined.
My difficulty here is that I have not yet even established
unambiguously what astronomers mean by apparent magnitude and apparent
brightness in the context of supernovae.
Wiki defines luminosity, in the context of astronomy as the amount of
energy a body radiates per unit time (i.e. power). Now, apparent
luminosity and bolometric luminosity will clearly depend on the
distance...
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Author: Oh NoOh No
Date: Dec 20, 2006 06:30
Thus spake Chalky bleachboys.co.uk>>Replied to in no particular order.
>
>Oh No wrote:
>
>> Thus spake Chalky bleachboys.co.uk>>
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Author: ChalkyChalky
Date: Dec 20, 2006 02:20
Replied to in no particular order.
Oh No wrote:
> Expansion has nothing to do with things moving away from a point, which
> you could model in SR.
Please then explain how to do _that_ in SR, relative to any one of
those things, at sci.physics.research. The thread has already been
started under the title "Relativistic addition/subtraction of
velocities", now changing "to exploding relativistic bombs". The given
formulae are a bit ambiguous when it comes to subtraction of
velocities, and all options then give superluminal velocities in 2 (and
3) dimensional space, when v is close to c (as with the particles
emitted on exploding a thermonuclear weapon inthe stratosphere).
> First ask what expansion means. Expansion relative to what. The answer
> is expansion relative to the immediate past. Hence rate of expansion as
> the ratio H(t)=adot/a. Acceleration/deceleration refers to whether or
> not this is a constant rate, or whether it is increasing or decreasing.
Yes, I understand that. This is no better and no worse than defining it
as inertial motion.
> Thus spake Chalky bleachboys.co.uk>
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Author: Oh NoOh No
Date: Dec 19, 2006 02:42
Thus spake Chalky bleachboys.co.uk>>Oh No wrote:
>
>> Thus spake "John (Liberty) Bell" accelerators.co.uk>
>>>>>Absolutely.
>>>
>>>A particularly informative link in this respect is
>>> http://www.astro.ucla.edu/~wright/sne_cosmology.html, based on the
>>>latest Riess dataset at http://arxiv.org/abs/astro-ph/0611572
>>>
>>>I note, however, from the error bars in the binned data at z ~ 0.5,
>>>within the third graph (fourth figure) here, that none of the
>>>traditional cosmological models get it right.
>>>
>>>I further note that the error bars at z ~ 0.4 and z ~ 0.6 are similarly
>>>tightly constrained, making the trend over the range 0.35 < z < 0.65
>>>crystal clear (for the real universe). >>
>> To be honest, that looks like errors in the data or in the analysis to ...
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