Hubble only observed around 46 galaxies. His experiment has been redone with more advanced telescopes, including the space-based hubble telescope.
Again you (qwaider) have hit upon a good point in saying that the data may be deceptive… in science we can never declare a theory ‘proven’ we can only declare it to have ‘strong supporting evidence’, and the more tests there exist for a theory the stronger the evidence becomes.
The expansion of the universe is not only based on the observation of galaxies and their redshift. A consequence of universal expansion is the Big Bang, a consequence of that is that the universe must be filled with radiation with an average temperature of 2.7K. A measurement of that is in fact is an indirect measure that the conclusion of an expanding universe is probably correct.
Now, the radiation was detected in 1965, and it was found to be homogeneous and isotropic across the sky. This means that no matter where u pointed ur telescope in the sky u would measure 2.7K. This would not be possible unless the origins of the universe were homogeneous across the sky, and also the universe today. This means, observing galaxies in one region of the sky would produce practically the same results as observing galaxies in another region (pretty neat I think).
Again, a precise measurement of this radiation has been made by space based missions (which can detect varations on the micro-kelvin limit) confirm that the average temperature of the radiation regardless of where in the sky is uniform. Check NASA’s WMAP site for more details on this type of mission.
The WMAP sattellite though also measures the light detected by galaxies, so again a confirmation of results done by Hubble type survey’s.
In conclusion, the expanding universe has VERY strong supporting evidence 🙂
hope I have convinced readers… I will get onto the questions on the Big Bang later.