harrycostas":10oyk4ea said:
Hello Speedfreek
Thank you for those links. I have read them before. Before I read them again pick one for discussion.
That's the problem you are having - these issues need to be taken
as a whole in order to see the overall picture. No single observation can show that the universe is expanding, you have to take all the observations and consider the wider view.
This is why all your talk of jets emitted from Active Galactic Nuclei fails to make an impression - you don't say what the implications of those observations are, for the universe as a whole. Well, actually you do say something, you make a simple assertion that those observations should make us
question whether the universe expanded from a hot, dense state to a cooler, less dense state, carrying matter along for the ride in the process (Big-Bang Theory), but you don't say
why we should question it, based on those jets.
What aspect of the expansion model do those jets address, and how do they relate to other observations? Do
all galaxies have active nuclei, emitting jets that form dwarf galaxies around them? Why does the redshift of
all galaxies (outside of our local area) increase, with distance (as luminosity decreases)? Why do we only see blueshifts for galaxies in our own supercluster, whilst all other superclusters show increasing redshift with distance? What have your jets got to do with this? How do your jets relate to the Cosmic Microwave Background Radiation, which comes in at the same temperature (with incredibly small fluctuations) from all directions?
Our experiments in particle accelerators have given us a clue what a universe would be like if it was once in a very hot dense state. A theoretical prediction is made, based upon these experiments - nucleosynthesis at a universe scale, which should produce as an end-product a background radiation at a similar temperature throughout the universe.
Any small fluctuations in temperature can be attributed to fluctuations in the density of energy/matter in those regions, so we end up with an almost uniform universe, expanding as it cools. Gravity is the weakest force, and the universe is too energetic for it to take hold at first, but after a while it is cooler and less energetic and gravity takes hold in the denser areas, making them even more dense, whilst there is less gravity in the less dense areas. The matter in the universe "clumps up" as it expands, with the clumps separating, due to that expansion. Eventually those clumps form into clusters of galaxies, so we have denser regions of galaxies with less dense regions around them. The earliest galaxies would have "condensed" in a random way, before they had time to gravitationally interact with other galaxies in a swirling dance that forms spirals or regular looking ellipses. The first galaxies would look
strange.
Theory tells us that the early universe was full of only the simplest elements, so the first generations of stars would have been formed from the lightest elements. Theory also tells us that any heavier elements are formed during the highly energetic events at the end of stars lives. So, in a universe expanding from a hot dense state, as time goes on, the ratio between lighter elements and heavier elements will be changing throughout the universe. There should be an abundance of lighter elements earlier on, when compared to later.
These are some of the predictions of the Big-Bang theory, and those links I gave show how our observations match with the prediction. I'll stop here for now, but as you can hopefully see, you have to appreciate the whole picture before you can make sense of how the individual observations are involved.
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