Big Bang (please, watch these videos)

Part 2 here.

What is the age of the universe? The best available measurements as of 2010 suggest that the initial conditions occurred between 13.3 and 13.9 billion years ago.

What caused the BB? Remember: The question doesn't make much sense. It's meaningless. However, it's still logically possible to imagine that the universe is caused.
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Here you have the evidence for BB in 10 minutes!