How do scientists know galaxies change over time?

Radio telescopes have played a pivotal role in the understanding of galactic evolution. Their ability to “see” regions beyond the optical view of a galaxy, have brought significant insights into how galaxies form and develop. However, despite this progress, it is still a mystery as to how the early galaxies, in the millions of years following the Big Bang, began to evolve: where did they get their material? what drives their rotation? what has shaped them? The SKA’s unrivalled sensitivity and resolution will be able to track young, newly forming galaxies at cosmological distances, and, through mapping the distribution of Hydrogen, help us unravel these key mysteries.

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