  We discuss why AI is hard and why physics is simple. We discuss how physical
intuition and the approach of theoretical physics can be brought to bear on the
field of artificial intelligence and specifically machine learning. We suggest
that the underlying project of machine learning and the underlying project of
physics are strongly coupled through the principle of sparsity, and we call
upon theoretical physicists to work on AI as physicists. As a first step in
that direction, we discuss an upcoming book on the principles of deep learning
theory that attempts to realize this approach.
