The color gauge theory postulates the existence of eight massless particles, sometimes called gluons, that are the carriers of the strong force just … - Sheldon Glashow

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.

... If a distant galaxy is moving relative to us, its entire spectrum is Doppler-shifted in frequency. Its spectral lines are displaced relative to those of stationary light sources. Thanks to this effect, we know that distant galaxies recede from the solar system at speeds proportional to their distances from us. That's the effect that told us of the expanding universe, and of its birth, long ago, in the Big Bang.

Why was there a Big Bang? What, if anything, came before? What mechanisms generated the exponential inflation of the early Universe? What are dark matter and dark energy, which dominate today's Universe? How did the first stars and galaxies form? Why are the fundamental constants of nature what they are? Must we depend on the Cosmic Anthropic Principle to 'answer' such questions? Is our Universe unique, or must we appeal to a Multiverse? What will be the ultimate fate of our Universe?