  After reviewing the difficulties faced by the conventional theory of planet
formation (based upon the aggregation of microscopic dust particles), we
describe an alternative hypothesis. We propose that planets form by
gravitational collapse at the same time as the star about which they orbit.
This 'concurrent collapse' hypothesis avoids theoretical difficulties
associated with the conventional model and suggests satisfying explanations for
various poorly understood phenomena. We introduce new explanations for FU
Orionis outbursts seen in young stars, the discovery of exoplanets with
eccentric orbits and the existence of small rocky objects such as chondrules in
the solar system.
