  From the time the first stars formed over 13 billion years ago to the
present, star formation has had an unexpectedly dynamic history. At first, the
star formation rate density increased dramatically, reaching a peak 10 billion
years ago more than ten times the present day value. Observations of the
initial rise in star formation remain difficult, poorly constraining it.
Theoretical modeling has trouble predicting this history because of the
difficulty in following the feedback of energy from stellar radiation and
supernova explosions into the gas from which further stars form. Observations
from the ground and space with the next generation of instruments should reveal
the full history of star formation in the universe, while simulations appear
poised to accurately predict the observed history.
