New Scientist - 19 May 2010
DID the big bang boil? The birth of our universe could have seethed with hot bubbles and, perhaps, a second period of rapid expansion. Such an episode may have left an imprint on the universe that persists to this day and might mean we're on the wrong track in our hunt for dark matter.
Just 10-37 seconds or so after its birth, a period of inflation is thought to have caused the universe to balloon in size. This process is thought to have amplified tiny quantum fluctuations in the vacuum, giving rise to the megastructures we see all around us in the universe today.
A second profound transformation is thought to have followed hot on the heels of inflation. Just microseconds old and at trillions of degrees, the universe condensed from a superhot soup of sub-nuclear particles called a quark-gluon plasma (QGP) into particles such as protons and neutrons. But exactly how this happened is far from clear.