The Big Bang - What initiated it?

In the beginning . . . the occurrence has intrigued scientists for many years. Exactly what happened, and how? Celestial measurements indicate that there was, indeed, a beginning. Calculating that there had to be a beginning, however, is very simple in comparison to developing hypothesis on exactly what happened! Over the years, there has been a variety of suggestions on how our universe was begun. Right now the 'correct' answer is a 'Big Bang.' This may be what actually happened, or it may give way to a better theory as time goes by, but no answer can be definitive. To prove any theory viable, we must be able to reproduce the associated event. We can never reproduce the initiation of a universe, or even a small model of the occurrence. Therefore, the Big Bang theory will never be more than an unprovable theory.

An even greater question is, "How did it happen?" And this is a question that, someday, may possibly be answered. Einstein's calculations resulted in the relationship, E=MC², i.e. Energy is equal to Mass times the speed of light squared. More realistically, it probably should be M=E/C². Scientists now know that all atoms are constructed of small packets of energy, much in the same way that a building may be constructed of bricks. There are attractive forces between the energy packets that serve as mortar, holding them together. The speed of light is about 3x10⁸ meters per second, so every unit of mass must contain about  9x10¹⁶ units of energy. Whatever the appropriate units may be, it means every ounce of mass is made from a huge amount of energy. Experience with atomic bombs does confirm the truth of this relationship. 

The huge questions now are:
If the universe was, in truth, begun with anything approaching a 'Big Bang', where did the infinitely immense amount of energy contained in our universe come from?
and
What initiated the energy to mass conversion?
Did none of those studying the Big Bang ever consider this question, or was the implication so 'mind blowing' that no one wants to tackle it?