Answer:
we are the evidence of the big bang and everything you see.
The evidence that the space that constites our Universe has been expanding since about 13.7 billion years ago is overwhelming.
1) all galaxies outside our Local Group are red-shifted, meaning the distance between these galaxies and us is increasing.The size of this red shift is directly proportional to the distance between us and those galaxies. The time when all of the visible (to us, anyway) matter was compacted as far as we can understand, is called the Big Bang. Calculation of the Hubble Constant gives that time at about 13 billion years ago. Interestingly, this time agrees with the ratio of slow-decaying elements AND the age of the oldest known stars.
2) this hypothesis predicted, in 1946, the existence of an isotropic and uniform microwave radiation whose spectrum would match that of a black-body at 3.7 K. The cosmic microwave background radiation was found eighteen years later and corresponds perfectly with the prediction.
3) the hypothesis predicts that all parts of our Universe would constitute 90% hydrogen and 10% helium -- exactly as seen.
No other hypotheses can explain (2) or (3) better than saying, "That's just the way our Universe is -- we can't explain why."
4) Long-evolved galaxies are seen close to us, but none are seen far from us. This is impossible to explain EXCEPT with the simple idea that, at a far distance from us, we can ONLY see galaxies that have not had time to evolve for a long time.