loudube wrote:Is that the same red shift the universe to be expanding? Couldn't dust be the explanation there as well!
Maybe that's the way dark matter shows itself.
I like this hypothesis. I'm not an astronomer or physicist -- I'm a total amateur. No doubt one of the more experienced people on this forum will argue with this. But I've been wondering this same thing since I first learned of the redshift years ago.
What I see in Wikipedia leads me to believe that Hubble himself held to the view that his redshift law was an observational truth, but open to various interpretations. That it is perhaps caused by something else, not the recessional velocity of the galaxies nor the expansion of the Universe.
If you look at this article http://en.wikipedia.org/wiki/Hubble%27s_law
, the terse mention of it there is that Einstein visited Hubble and thanked him: "In 1931, Einstein made a trip to Mount Wilson to thank Hubble for providing the observational basis for modern cosmology.". However, if you look at this biographical article http://en.wikipedia.org/wiki/Edwin_Hubble
, it appears that while Hubble was supportive of certain other interpretations of the redshift, he remained undecided himself on the ultimate interpretation. That article has:
To the very end of his writings he maintained this position, favouring (or at the very least keeping open) the model where no true expansion exists, and therefore that the redshift "represents a hitherto unrecognized principle of nature."
In fact, Einstein apparently once visited Hubble and tried to convince him that the universe was expanding.
Which is a very different accounting of the matter.
We have plenty of examples of dust reddening. Our own sun shows it in the sky every morning and evening, and I don't think it is racing away from the Earth at those times.
That this cluster's light reaching us is reddened by dust seems pretty "solid".
So, what is the reddening of light as it travels across intergalactic space for billions of years? I have not studied General Relativity. Evidently it predicts it as space itself expands. But for now, I (though I am just one unlearned amateur voice among the noise) believe it is most likely simply a loss of energy from the photons to the medium through which they travel. I would even hazard the guess that the microwave background is made up of the very tired photons that have traveled perhaps even trillions of light years and have lost so much energy that they are now microwaves.
But, I admit that I am sharing much ignorance with you in this response. Perhaps someone with more training in physics and cosmology will come along and either offer more support, or offer contrary arguments, theories, or evidence.