"Just as one can compose colors, or forms, so one can compose motions," Calder stated shortly before making this work. One of Calder's first mechanized mobiles, A Universe presents his abstract vision of the cosmos. A small red sphere and a larger white one suggest planets and move along curved wire paths at different speeds, completing a full cycle in forty minutes. Calder constructed a motor that propelled the spheres' movements, using his training as a mechanical engineer.
Reflecting on his work of this period, Calder commented, "At that time and practically ever since, the underlying form in my work has been the system of the universe." His personal fascination with the solar system was part of a wider phenomenon, prompted in part by the discovery of Pluto in 1930. Calder's interest in astronomy and physics was not one-sided, however. When A Universe was first exhibited at the Museum, Albert Einstein reportedly stood transfixed in front of its slowly moving orbs for the entire forty–minute cycle.
from Focus: Alexander Calder, 2007