harrycostas":16kzd0y8 said:
The papers that you posted are out of date and give little consideration to the intrinsic properties of supernova. Since we use the supernova as a standard candle we should eliminate the errors and understand that redshift can be created by many processes, even when the object is moving towards us.
Harry, the supernova data is just
one type of standard candle used to
calibrate the "distance ladder", I thought we covered this some pages back in this thread
(at least I think it was this thread!), where I listed
all the various measurements used on the distance ladder, all of which are in agreement with the expansion of the universe.
Hubble did not use supernova data, he used Cepheid variables. Most of the evidence for expansion has
nothing at all to do with supernova data. The recent supernova data is just one of
many ways that we confirmed not only the expansion, but the
acceleration of the expansion. You hear about the SN data a lot, as it is the most recent confirmation.
Whether Hubble thought that the universe was expanding or not is irrelevant - the answer is in the data, not the opinions of the author. Einstein himself did not want to believe the universe was expanding either, until he was presented with the evidence.
All galaxies
(not supernovae, but galaxies) outside of our local supercluster are redshifted and the amount of redshift increases as apparent luminosity decreases.
Then, over a certain distance (as measured by apparent luminosity), the apparent angular diameter of objects starts to increase, implying that those objects were close to us when they emitted the light (which is now very dim) that we see. That relationship, when combined with the previous one, is even harder to explain using an alternative model.
Then, the ratio of light to heavy elements increases as we look at increasing distances, so those most distant galaxies were mainly comprised of light elements, whereas modern galaxies contain a much larger concentration of heavy elements. That, when combined with the previous two relationships, is
even harder still to explain using an alternative model.
Then we have the existence of the cosmic microwave background radiation, which is predicted in an expanding universe, due to nucleosynthesis when everything was much closer together than it is today. An alternative model needs to explain what all this very cold background radiation is doing here.
The list goes on and on... large scale structure formation (there were less galaxies around 13 billion years ago), the age of stars (the lowest mass stars have potential lifetimes of trillions of years, yet we see none older than 13 billion years old), the evolution of galaxies (the most distant of the galaxies in the Hubble Ultra Deep field look strange and irregular, nothing like modern galaxies), and then finally we get on to supernovae!
We have the time-dilation of supernova light-curves, which seem in general to correspond with all the previous relationships, as predicted in an expanding universe. The more distant the supernova of a given duration, the longer the apparent duration when we finally see it - cosmological time-dilation caused by the expansion of the universe.
Unless, that is, you think that galaxies actually used to be twice the size, all at the same time, in a universe that was static and had no beginning... or that supernovae used to burn for a lot longer than they do nowadays, in a universe that has always been here. Or that galaxies used to be comprised of lighter elements than today, for some unexplained reason. Or that the universe has always been here, but we have seen no stars over 13 billion years old. Or why there used to be less galaxies, and they looked strange and irregular.
Did our universe have a beginning? It certainly seems so.
Is our universe static? It certainly seems not.
Is the universe cyclic? Perhaps it is, but if so, that cycle includes the expansion of our universe from something where the gaps between things were very small, to a universe where the gaps between things are very large. In that case, everything in our current "cycle" is as described by the Big Bang.