Strong, weak and electromagnetic interaction are evidently part of a grand unified theory. These temperatures are today quite inaccessible. They were achieved only in the earliest moments of the Big Bang. Since then, the universe has congealed, losing its symmetry.
Sheldon L. GlashowRelated topics
early inaccessible interaction losing quite symmetry todayRelated quotes
Found that in a universe that is expanding after a big bang event, neutrinos would turn up at a detector before they were emitted. Only future-going neutrinos were possible in the Steady state cosmology while the ever-expanding big bang models gave neutrinos travelling into Steady State theory to the past.
Jayant Narlikar