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cmancone
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| Joined: | Thu Oct 12th, 2006 |
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| Posts: | 33 |
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Posted: Thu Oct 19th, 2006 04:01 pm |
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I'm afraid Lyndon that you have a very bad assumption in your theory. Obviously, collision cross sections between photons and electrons are an important part of your process and the IGM. However, you have retrieved the equation you use for cross sections from study of low energy x-rays. You have then assumed (incorrectly) that this equation applies for lower energy photons such as optical light and infrared light, which are what are actually being redshifted. I'm afraid that this assumption is patently false. Perhaps you are familiar with the particle/wave duality of light? It is an effect of quantum mechanics that notes that light can act both like a wave and like a particle. Which one it acts like depends largely on the scales involved, and on the energy of the photons in question. Low energy x-rays interacting with electrons fall squarely in the regime of the particle nature of light. This is because of the small scales involved and because an electron and xray have somewhat similar sizes.
Unfortunately, optical and especially infrared photons don't necessarily interact with electrons the same way. The have a significantly different wavelength, and as such, most likely collide with electrons in a manner more fitting a wave hitting a rock on a beach. Since optical photons most likely collide with electrons differently than do xray photons, the equations for collision cross sections can be very different. In order for your suggestions to have any hope of being valid, you must use the collision cross sections of optical photons with electrons, not xrays. You can't simply assume that the results from xray scattering scale down to optical wavelengths. In fact, this is a very bad assumption.
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lyndonashmore
Administrator
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Posted: Fri Oct 20th, 2006 11:20 am |
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Nope,
Photons are photons and ther same processes happen to IR, light as happens to low energy X rays,
try this
http://www.newton.dep.anl.gov/askasci/phy00/phy00465.htm
The collision cross sections are spot on.
One way to test an assumption is to 'suck it and see' or 'the proof of the pudding is in the eatng".
I extend the cross section a little further nto the lower frewuency ranges, derive a formula for the hubble constant (H = 2nhr/m), substitute pulished values into this and predict a value for h which is spot on with observation.
What more do you want?
Cheers,
lyndon
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cmancone
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| Posts: | 33 |
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Posted: Fri Oct 20th, 2006 01:31 pm |
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Having done much astronomy research, I assure you that you can't assume that photons behave the same at high frequencies that they do at low. In fact, if you were to make that assumption you would almost certainly be wrong. The link you provided has nothing to do with this discussion. I'm going to be out of town for half a week or so, but when I get back I'll try to find a link for you to explain this, since you don't accept what I'm saying.
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cmancone
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| Posts: | 33 |
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Posted: Fri Oct 20th, 2006 01:47 pm |
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Real quick. Here's an example of something that demonstrates what I've been talking about. In many experiments, the results you get can change dramatically between low energy and high energy photons:
| http://en.wikipedia.org/wiki/Photoelectric_effect http://hyperphysics.phy-astr.gsu.edu/hbase/mod1.html |
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lyndonashmore
Administrator
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Posted: Mon Oct 23rd, 2006 06:00 pm |
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Sorry,
link does not seem to work
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Pete Carroll
Guest
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Posted: Thu Oct 26th, 2006 02:58 pm |
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Assuming that the spatial horizon of the universe is of the order of 10^26 metres away and that the density of intergalactic particles is of the order of 10^-25kg/m^3 then is it valid to calculate on the basis of what would happen to photons traveling through just 1 metre of a density of 10kg/m^3 ?
Pete.
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cmancone
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| Posts: | 33 |
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Posted: Thu Oct 26th, 2006 03:32 pm |
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It was two links, not sure why they appeared on one line:
http://en.wikipedia.org/wiki/Photoelectric_effect
http://hyperphysics.phy-astr.gsu.edu/hbase/mod1.html
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cmancone
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Posted: Thu Oct 26th, 2006 03:34 pm |
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I'm afraid I don't follow Pete. Can you restate your question?
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Pete Carroll
Guest
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Posted: Sat Oct 28th, 2006 10:27 pm |
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Okay, let me put it this way, I'm content with the idea of gravitationally redshifted light to explain the cosmic redshift, but the cream on the cake for any alternative theory to the big bang seems to have to involve a convincing explanation for the CMBR.
Now if we assume that the CMBR arises from the temperature of the local intergalactic material warmed either by starlight or the energy somehow dumped by cosmic redshift, then how do we explain that we do not see the spectrum of the CMBR spread out by redshift itself?
Does radiation get absorbed preferentially at certain wavelengths?
Does this mean that starlight travels further than the CMBR?
Can we treat the intergalcatic medium as having a certain particle density per megaparsec or whatever, or do we really need to summate the probability of photon/particle interaction at some other scale?
Pete.
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