The term “Hubble tension” refers to discrepancies in the value of the Hubble constant, which in turn indicates the rate of expansion of the Universe. In particular, the “tension” arises because two different techniques for calculating the constant give significantly different values. For a brief introduction to the Hubble constant, see https://physbang.com/2026/04/26/red-shift-and-the-age-of-the-universe/ or NASA’s summary … Continue reading Hubble Tension Part 1: The Distance Ladder
Red-Shift and the Age of the Universe
Stars can be characterised by their absorption lines, which reveal their temperature and composition. There is more detail about this in two recent posts about the HR diagram and stellar classification. A similar approach can also be used to characterise entire galaxies but in this case the aim is to determine how quickly they are … Continue reading Red-Shift and the Age of the Universe
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