In our theory we have multiple mini bangs and these mini bangs are not mysterious like the big bang but they come because of the concentration of what we call negative energy fields. Whenever there are pockets of negative energy, they explode and produce a mini bang. We believe there's a mini bang producing energy in the centre of quasars, which are very bright star like objects. Gamma ray bursts, which are the explosive creations of gamma rays, are another example of a mini bang. These are actually happening. These can be described by normal physics, but the big bang cannot. The big bang theory does not use any mathematical formulation so they can't say why the bang occurred.
Jayant Narlikar's Cosmology