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Physics, Astronomy & Cosmology / Re: Are black holes the oldest known part of the Universe?
« on: 30/12/2017 21:31:26 »Quote from: unstman
I would like to know if the age of the Universe is only based on visible matter?Yes, mostly.
- Scientists are still trying to detect invisible (Dark) matter, without success (so far).
- The age of the universe is derived from the Hubble Constant, which is based on the Distance and Doppler shift (velocity) of distant galaxies,
- with the distances measured by a cosmic ruler consisting of Cepheid variable stars and supernovas, which are all visible phenomena
- But hints are also available from variations in the CMBR and gravitational waves from the 2017 neutron star merger, which are non-optical phenomena.
See: https://en.wikipedia.org/wiki/Cosmic_distance_ladder#Standard_siren
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In other words, the furthest visible matter we can optically observe?The most accurate measures are taken from galaxies which are much closer (and hence appear brighter), and are able to provide a clear spectrum from which to derive the Doppler shift.
From reasonably close galaxies (but outside our local cluster of galaxies) we can extrapolate to a time when all these galaxies were all close together.
However, if you wish to measure the accelerating expansion of the universe, then this survey must include many galaxies beyond 5 billion light-years, which is a challenging measurement.
See: https://en.wikipedia.org/wiki/List_of_the_most_distant_astronomical_objects
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If the age of the Universe is 13.82 Billion Years Old, How old would the Universe be to an observer at the edge of what we perceive to be the age of the UniverseWe expect that an observer (say) 12 billion Light Years away might be able to see the precursors to our galaxy.
- She may well be able to see galaxies that we cannot see from Earth
- She will certainly see galaxies at a different stage in their life-cycle than we see from Earth
- But based on measurement of galaxies near herself, we expect that she would conclude that the universe was a similar age to us
- This is because all galaxies are expanding away from each other, at a rate which is (roughly) proportional to distance