Where The Bang Came From?, big bang theory question

I am very armature, but curious. From my limited understanding, the big bang came from a point of energy that was infinitely small. I understand that the universe is expanding, and that by working that expansion backwards scientists have concluded that the universe is approx. 13.7 billion years old. But what I am clueless about (besides most of this) is why it is believed that the universe derived from an infinitely small point. I pose this question, and it may be stupid but, why couldn't have the expansion come from a huge mass, which contained all of the matter in the universe, and that is what exploded or expanded.

If i light a stick of dynamite, and you record the explosion nano seconds after it began, you could reverse the tape, and see the explosion backwards but only to a certain point. Based on that observation you could do the math and work the explosion back to its origin. Would you then conclude that the explosion came from a single point, an infinitely small point which created all of the matter that is shown flying away from the origin of the explosion?

The total mass + energy was always there (immediately after the big bang). Are you asking a question about the volume?

What i am asking, is why the big bang started from an infinitely small point, and not something larger, like a gigantic super sun or something? So yes, why wouldn't the volume be something larger than an infinitely small point.

http://en.wikipedia.org/wiki/Big_Bang

Note the description of the timeline - specifically the breakdown of relativity theory.

I too have often wondered about the "point" vs volume or "ball" (of whatever size) of cosmic origin.
Steven Hawking once said, describing cosmic origin as a singularity, that the whole observable cosmos came from "a point of zero volume and infinite mass density."

How could a point of no volume contain anything, much less everything?
I think he later abandoned the above in favor of endorsing M-theory, or maybe he holds both to be possible contenders... not sure.

The question, "Where did it all come from in the first place?" is one of my 'special interests' too. An oscillating model would explain it if enough matter is found to reverse the expansion... plus some other "bugs" needing to be worked out.

It's not an infinite small point. The following is the best model for the beginning of our universe. Brought cosmology to predictive science. Guths inflation.

http://www.counterbalance.org/cq-guth/index-frame.html

http://ned.ipac.caltech.edu/level5/Guth/Guth_contents.html