About the concept of matter and that it cannot be created:
Matter can be converted to energy, or reversed.
That is how fission and fusion work. Fission works by colliding 2 atoms to create 1 larger atom whose mass is lower than the total of the 2 reagents. The change in mass is converted to energy in the form of heat that is then used to drive turbines to generate electricity.
The same applies to fusion. How this can work is that the lowest mass/matter-ratio on the table of elements is iron, which has the element mass of 55.8 (compared to 1 for hydrogen or uranium with 238).
This is why the cores of stars (which start as gas clouds, hydrogen etc.) is eventually made of iron. The creation of higher mass/matter-ratio elements are formed from supernovae where the immense amounts of energy start higher mass/matter-fusions. The immense energies also start fissions so more smaller atoms are re-created.
The big bang theory works somewhat like this:
A huge amount of energy and/or matter gathered in the universe, resulting in a colossal explosion (and conversion of energy to mass).
Scientists have noted that all astrological parts are moving away from us, at different velocities, which would indicate that the universe is still expanding.
The theory of continuation I find most believeable is that (because of gravity, although weak and over immense periods of time) in the end, the universe will start to contract and shrink. This would then eventually lead to a new "big bang", after all mass and energy has been gathered again.
This would mean that the universe we live in now could be just one in a series of "big bang" universes.
Also, the formula for gravity between bodies of mass is constant, and exists everywhere. No questions there (from me at least).
Just thought I'd try clear things up with the matter/energy/gravity part for y'all. The theory of continuation-part is just the theory I cling to.