|Apr22-12, 10:24 AM||#1|
Cosmological redshift alternative explanation?
Could the cosmological redshift be explained also as a change of the fundamental physical constants with distance? Say Planck's constant changing over billions of light years, instead of interpreting it as a Doppler effect due to a recession speed? Yes, I know, Occam's razor would favor the standard interpretation, but I'm wondering if there are concrete reasons for we can exclude this possibility for sure?
|Apr22-12, 12:48 PM||#2|
there are so many reasons that all fit together. I expect others will point out reasons to you why that picture doesn't work.
You are imagining a static universe where everything stays the same distance apart and the redshift is due to the light emitted/absorbed by a hydrogen atom, say, having been longer wavelength in the past. So one or more constants of physics change thru history always at just the right rate to make the emitted and absorbed light always the right color.
So many reasons. Like e.g. why wouldn't the static universe fall together.
But, not to take away from reasons other people may provide, I want to mention an interesting thing that is remotely connected to this. It might interest you.
You know what "arc second" or "second of angle" is----a minute is 1/60 of a degree and a second is 1/60 of a minute. So a second (") is 1/3600 of a degree.
If we see an object and its light is redshift 1.65, say, then if it is 1" wide then we estimate that it is 27,900 lightyears wide. A medium size galaxy, so to speak.
A similar object, say about the same actual size, if its light is redshift 3.65, then how big would it look in angular size? Would you not expect that because it is farther away it would look smaller and would have angular size LESS than 1"?
But in fact its angular size would be 17% larger. It would be 1.17", that is 1.17 seconds of arc. You think because farther it should look smaller, but in fact things farther than z=1.65 look BIGGER.
You might find this effect interesting. It applies most strongly to the temperature map of the CMB ancient light. One sees density ripples---*sound waves* in the hot gas. We know the temperature of the hot gas that emitted the light and so can calculate what the speed of sound was and what size waves to expect. We can get a handle on the *angular sizes* of these fluctuations in temperature and density. So there are objects out there at a known redshift whose physical size we can estimate, as it was when they emitted the light. And compare that with their angular size now.
Many different kinds of data to explain and fit together.
|Apr22-12, 01:23 PM||#3|
Yes, but, this explanation rapidly falls apart in the face of other observational evidence, as marcus explained. For example, the fine structure constant - http://www.eso.org/public/images/eso0407a/
|Apr22-12, 02:30 PM||#4|
Cosmological redshift alternative explanation?
Anyhow, I think that the change of constants conjecture could perhaps arrange for that since also the atoms size (and therefore the size of which the galaxy is made of) depends from fundamental constants. I know that this sounds wired, but science is after all also about the exclusion of other alternatives, as crazy they might be.
Moreover this recent paper might be interesting: http://arxiv.org/abs/1202.4758
And also: constancy in \alpha does not imply constancy of the values it is made of, we can have smaller \hbar and larger c, and maintain \alpha invariant, etc.
|Apr22-12, 09:58 PM||#5|
Varying hbar and c, or e, so as to maintain an invariant, or painfully slowly evolving fine structure constant just adds a fine tuning problem to an already messy idea. The authors of the paper you reference do not convincingly rule out systematic error, instrument bias, Mg evolution, or other unidentified cosmic factors as a possible source of the small variations in alpha reported.
|Apr22-12, 10:05 PM||#6|
What I'm talking about is not a special "effect" so much as kinder-grade cosmology. You can get it out of the basic calculator. Google "wright calculator" or "cosmo calculator".
Consider two redshifts z = 1.65 and z = 1090 (the redshift of the ancient light CMB.)
Consider objects each 27900 lightyears wide located at those two distances from us.
The nearer object will have an angular size of one arcsecond (1/3600 of one degree).
The farther object will have an angular size of 1/8 of one degree. That is the more distant object, though the same diameter, will appear to be about 450 times larger in the sky.
This is an elementary consequence of expansion. People don't write papers about it, as far as I know. Can't imagine why they should---well-known, one of many consequences of expanding distances.
I just picked the numbers because convenient for illustration. Because of expansion, older things look bigger in the sky, past a certain point.
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