  Previous simulations of the growth of cosmic structures have broadly
reproduced the 'cosmic web' of galaxies that we see in the Universe, but failed
to create a mixed population of elliptical and spiral galaxies due to numerical
inaccuracies and incomplete physical models. Moreover, because of computational
constraints, they were unable to track the small scale evolution of gas and
stars to the present epoch within a representative portion of the Universe.
Here we report a simulation that starts 12 million years after the Big Bang,
and traces 13 billion years of cosmic evolution with 12 billion resolution
elements in a volume of $(106.5\,{\rm Mpc})^3$. It yields a reasonable
population of ellipticals and spirals, reproduces the distribution of galaxies
in clusters and statistics of hydrogen on large scales, and at the same time
the metal and hydrogen content of galaxies on small scales.
