In recent years, deep learning has infiltrated every field it has touched,
reducing the need for specialist knowledge and automating the process of
knowledge discovery from data. This review argues that astronomy is no
different, and that we are currently in the midst of a deep learning revolution
that is transforming the way we do astronomy. We trace the history of
astronomical connectionism from the early days of multilayer perceptrons,
through the second wave of convolutional and recurrent neural networks, to the
current third wave of self-supervised and unsupervised deep learning. We then
predict that we will soon enter a fourth wave of astronomical connectionism, in
which finetuned versions of an all-encompassing 'foundation' model will replace
expertly crafted deep learning models. We argue that such a model can only be
brought about through a symbiotic relationship between astronomy and
connectionism, whereby astronomy provides high quality multimodal data to train
the foundation model, and in turn the foundation model is used to advance
astronomical research.Comment: 60 pages, 269 references, 29 figures. Review submitted to Royal
Society Open Science. Comments and feedback welcom
