Question

HELPPP ( Please)

What is the Big Bang theory? Why do scientists believe that the Big Bang theory is a correct model?

Answer 1

The wikipedia page of the Big Bang is very good: http://en.wikipedia.org/wiki/Big_Bang
You can read the introduction of this article.
Scientists believe it's correct beacuse the theory explain the expansion of the universe (which is an experimental fact, established by Edwin Hubble in ), the Cosmic microwave background radiation which was discovered by Penzias and Wilson in 1964 (they won a Nobel prize for this and they weren't even looking for it), the abundance of primordial elements and another stuff. You can see all of this in the Wikipedia article. The theory also has its problems, they have to introduce the dark matter for explaining some things and stuff in that style.
I recommend you to read the wikipedia article. It contains very good information,