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
The Hertzsprung-Russell diagram
It is obvious that the stars in the night sky differ from one another; some look brighter, some appear larger and some have different colours. One of the earliest ideas was that all stars are the same but they look different because they are at different stages of development: it’s as simple as the fact … Continue reading The Hertzsprung-Russell diagram
Mr Tarrant's physbang 'blog 