Solution to horizion problem ?

:rofl:

Well, there are variable speed of light theories cosmological models out there, and one of their inherent properties is that they solve the horizon problem. I don't know much about these theories but I would imagine that their problems would then lie in resolving some of the other problems that inflation solves.

With respect to your post, I'm not entirely sure what you mean and it seems pretty speculative to me (which is against PF rules). Light is redshifted through the entire range of the electromagnetic spectrum; there aren't two clear cut categories whereby the light suddenly jumps from one to another. I also don't know what you mean by the friction part of your post.

Anyway, I should remind you that you are not permitted to discuss personal theories here, but if you wish to talk about one of the published VSL cosmologies, then that is fine (so long as you cite it).

 

I wonder what evidence there is for this. ie how do we know from practice that this is so rather than theory.

 

Sounds like "Joao Magueijo's Big Bang" on the Science channel.
{h}ttp://science.discovery.com/tv-schedules/special.html?paid=48.8544.122181.0.0

 

The accepted picture says there HAS to be a microwave background of the observed temperature because
1. at a certain time the universe was 1000 times hotter and 1000³ times denser than it is today

2. before that moment it would have been a opaque glowing cloud of hydrogen and it would have been sending out light, right around the time the cloud cooled enough to become transparent.

3. so given the standard model, and what we know about hot hydrogen gas, the universe must now be full of that light but with the wavelength stretched out by a factor of 1000

and that turns out to be just what we see!
The accepted cosmology model says there HAS to be this microwave light all over this place, of just this range of wavelengths. If there weren't then it would be reason to discard the model.
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The acceptance of scientific views rests on empirical testing, which basically means testing PREDICTIONS.

General Relativity is the accepted theory of gravity because in 1915 it predicted a certain bending angle of light passing by the sun and in 1919 this angle was observed, and then after that came other tests to this day. Which it continues to pass with flying colors.

The basic expansion model of cosmology (Friedmann and others) derives from that theory of gravity: Gen Rel.
If you believe the accepted theory of gravity then you are probably inclined to believe the expansion cosmology because solving Gen Rel indicates that it has to be either expanding or contracting and by all evidence it sure isnt contracting!

Then in 1948 some people realized that if the accepted theory of gravity, Gen Rel, and the expanding model cosmology that comes out of that, are right then, from what we know about hydrogen gas at various temperatures, there has to be a microwave background coming from the early universe. It was a PREDICTION of a hitherto unexpected phenom.

And almost 20 years later, in 1966, some people who didn't know about the prediction and weren't looking for the microwave background FOUND the background was there more or less as predicted.

Basically the credibility of a scientific model rests on the fact that it predicts things that turn out to be right, and there is a premium on predicting things that are otherwise completely unexpected.

So you can say that the expansion model of cosmology (based on a well-demonstrated theory of gravity) has the very best sort of practical supporting evidence, namely that it predicted something totally unexpected that turned out to be there 20 years later.

And it has not been shot down. It continues to survive all empirical tests. All the new data that comes in is consistent with it.

Whereas alternative explanations for where some of the observed stuff might come from, like the microwave background, are always a bit strained and they always get shot down by some observation or other. Nobody seems able to think of an alternative model that fits all the data.

Which doesn't mean that people shouldn't try! Their should always be people trying to come up with alternative models, and testing them. Eventually one will show up that will be an improvement, no doubt.

And it doesn't mean that you, Henrieta, have to believe the standard model of cosmology either. You are welcome to doubt it. Skepticism is highly approved of. You are also welcome to make up your own model. But do try to appreciate the bulk of practical nuts and bolts evidence that weighs in on the side of the accepted picture.

 

Nor will he be the last. FTL theories are a dime a dozen because they fail miserably in the face of observational evidence. GR is not wrong and any theory that suggest otherwise is doomed to fail. I'm not saying GR is complete, but, I am asserting it is 100% correct at the low energy limit. It is, observationally speaking, the most successful theory in the history of science.

 

He maintains he is not contradicting GR or the relevant observations, i.e. light velocity is fixed constant now not in early universe AFAIR and that he has met this objection. I could not myself argue much for him.

 

I am not trying to be cantankerous here. I am happy with the present model. But 'has' is not science. Is there any observational evidence that links the accepted picture of expansion and the CMB? Just wondering