universe - Origin of the original bright light and matter

I assume that what you want to know is "where did everything come from?" As for the light and the matter itself, we have some pretty good theories: Matter consists of many different particles, each of which were created from energy at different epoch during the first few moments of the Big Bang (BB). For instance, leptons were created from 1 to 10 seconds after BB, hadrons from 10^-6 to 1 seconds after BB, and quarks even earlier. Light was created when the different particles annihilated with their corresponding antiparticles.

As to how the original energy — from which light and matter came — was created in the first place, there definitely is no well-grounded theory here, but either we must accept that

1. the Universe came into existence out of nothing, or else


2. there was something before that created the Universe, in which case we either
   
   1. just push the question further back, or
   
   
   2. must accept that whatever was there before has been there for eternity.
   
   

Option 2.2 is boring because I don't think there's any way of testing this theory, so option 1 or 2.1 seem most appealing, especially option 1, since time itself is thought to have been created along with space (though I think there are models where this is not necessarily the case).

Creating something out of nothing seems magical, but in fact it happens all the time. A vacuum is the lowest state of energy, but as a consequence of Heisenberg's uncertainty principle, in a finite time, the lowest state of energy cannot be zero, since ΔE Δt ≳ ℏ. This results in so-called quantum fluctuations. Usually, the energy popping up out of nowhere annihilates immediately, but there are ways of making it survive (e.g. on the border of a black hole). In a similar way, universes can be thought to pop up out of nowhere. Such a universe could annihilate immediately, but if inflated fast enough to a large enough size, it could grow to macroscopic size before it has time to annihilate.

If you want to read further, Wikipedia has some nice articles on the timeline of Big Bang and cosmogony (the theory of stuff coming into being)