The heart vs. brain analogy is a good one. My heart says God had something to do with it. My brain isn't sure what to think. I will admit that my knowledge of Physics is limited. I could have taken it my Senior year, but took Human Anatomy instead. I've already stated my issues with it. Everything has to come from somewhere; even God. I have theories about where God came from. The Big Bang Theory just goes against everything else I've learned as scientific fact.
Of course, one could always educate me. I've always loved learning. Typing it out here would be a waste of time. If you use 'formal' language I won't remember any of it. However, if anyone has any videos they could direct me to... I'm an auditory learner.
This is my understanding of it (and I'm not a scientist, just a student of physics -- minor not major, and I read a lot of science journalism):
When you burn an object you are inciting a chemical reaction in which the molecules in the object move at an accelerated rate that are adjacent to the source of heat. Eventually a chain reaction occurs as the molecular movement reaches a critical point and adjacent molecules made of the same matter begin to move at an increased rate as well, that's what happens when the object catches on fire. Smoke is certainly part of what's being given off in the ensuing chemical reaction, but heat is being given off as well, and heat literally is energy. If you were to collect the smoke and remains of the object you burned into a single unit of matter, then you could calculate the amount of heat given off:
Initial Matter (pre-burning) = Smoke Matter + Burnt Remains + Lost Matter Converted into energy. If you solved the equation for the lost matter, you could then calculate how much energy was given off by using e=mc^2, where e is the energy given off, m is the lost matter, and c is the speed of light which is a constant (you would also have to rearrange it as e/c^2 = m). Matter would only be conserved if the lost matter converted into energy was zero, which isn't really going to happen in any circumstance practically. Anytime friction occurs, you lose energy. When you destroy the bonds that hold solid matter together, energy is lost.
But this isn't a one-way street either. Energy can actually be stored as matter, this is what photosynthesis does. The sun's burning of gases gives off photons which are then absorbed by chlorophyll in plants. The plants have the faculties to turn this absorbed energy in the form of light into the very matter that is developed as they expand and grow. But there is a certain innate inefficiency to the process, and this is one way that entropy comes into account. No conversion of energy into anything else is 100% efficient; just as plants cannot harness every last drop of the energy given off by the burnt gases in the sun that crosses their path, no machine is capable of utilizing every speck of energy fed to it in order to do work.
All of this inefficiency working in tandem with the laws of thermodynamics and entropy means that as the universe ages, pure concentrated forms of energy are going to be harder and harder to find. It's almost like the fossil fuel crisis on a grand scale. Couple this with evidence that it's taking longer for us to send and receive flashes of light from distant galaxies, and scientists have surmised that the universe is expanding and galaxies are drifting further apart (though another alternative hypothesis has been proposed that the speed of light is not actually constant, and that space-time are changing, not the actual distances).
If you reverse the expansion and energy dispersion that seems to be occurring, the end result is a nearly infinitely dense, hot bundle of mass that was the beginning of the universe, which then exploded to form everything (the big bang). Because space was essentially "empty" before the explosion (or really kind of nonexistent), when the explosion occurred there wasn't anything for the "fiery edges" to latch on to in order to be absorbed like when an explosion occurs on earth.
I'm really kind of fudging the explanation here, but more or less, the echoes of the explosion are still out there and observable, they're called the "cosmic microwave background radiation," and when you extrapolate backwards, it confirms the notion of an initial explosion (it would be like watching an explosion from several miles away and knowing it happened because the light reaches you; it's just that these echos are much older and we're watching from a different viewpoint). These echoes of the big bang are the one thing that people who propose alternate theories to the big bang can't quite account for. The problem is, a lot of our understanding of the cosmic microwave background radiation is based on the existence of dark matter.
Isaac Newton came up with relativity (the notion that the speed of light is constant in all frames of reference), and as a consequences from this developed complicated theories about gravity. These theories were eventually applied to large bodies very far away moving at high speeds (which is where relativity comes into account big time). They didn't seem to describe physical phenomena right, that was when the idea of Dark Matter was proposed in order to account for the missing mass that would have to be there in order for the laws to hold. Dark Matter is very difficult to detect because it doesn't interact with light the way matter does. It's "there" but we don't know it's there, more or less. This is where things get very shaky, because dark matter has basically been taken for granted as an assumption (though attempts at verifying its existence were made at the same time, so that's not really the right way of putting it), and it's supposed to be symmetric with normal matter, but by calculations the universe is about 80% dark, and 20% normal.
There have been a lot of attempts at experimentally verifying the existence of dark matter with mixed results. It's still not 100%, and to a large degree a lot of the current popular cosmological model hinges on dark matter. If dark matter doesn't exist, there's a gigantic hole in the theory of gravitation that we're using which largely leads to the conclusions of Big Bang model.
There are a number of alternative theories which explain away the necessity of the Big Bang and Dark Matter, but as of now they're not very competitive. They simply aren't as likely because they don't explain as many phenomena as the Big Bang and Dark Matter do. What proponents of science must realize is that all of the experiments and data we have collect in order to construct our theories could potentially only be one side of the coin. As we discovered when the flaws in Newtonian Mechanics became apparent, new avenues of evidence and perspectives can be made available which fundamentally change the entire structure of our scientific understanding of physics.
We can never really know if we're seeing the whole picture or just paying attention to a set of special circumstances where the laws which we are observing are simply applicable to what we can see. I guess that's why I feel so shaky about making propositions about the existence of everything based on science which is largely unsolved and not without its fundamental problems: god is kind of the ultimate endgame of everything. Until we can run a simulation of the universe's birth, death, revival, and processes without fault, I'm not willing to extrapolate anything solid about the very nature of existence from simple analysis of data. It seems like something better left to philosophers and the religious.
EDIT: The whole brain vs. heart thing is a fallacy of reification. There is no heart in the sense that you're thinking. The heart is an organ that pumps blood throughout your body to keep you living; it has nothing to do with your cognitive state. This is more like the higher reasoning potential of your brain versus impulses and instinct. Which isn't really anywhere near as favorable of a description of the "heart" side.
Science uses imagination, impulse, and creativity as well. Formulating a hypothesis to test is an art in and of itself, based entirely on intuition. You can't reject the value of following your instincts, it's just always a good idea to keep them in check with your higher reasoning too. That's the secret to science's success. And there's nothing stopping religion from following suit. A little doubt is healthy.