Question

Extraordinary claims require extraordinary evidence is an idea widely popularized by Carl Sagan. Obviously no one amongst us was present to watch the big bang unfold, what evidence do we see today to indicate our Universe started with a big bang? In your own opinion, is the evidence in favor of the big bang theory extraordinary? Describe one observation that people could make today that would contradict this evidence.

Answer 1

The most clear evidence of the big bag and the xpanding universe is that all galaxies/stars/systems are moving aways form each other at similar rates.

It also explains there was a common start point, i.e. the explisino of the big bang.

The evidence is nota that extraordinary, even though it assumes that the universe has been acting the SAME for the 14 billiion years old.

The main observation which people could state to refute/contradict this is :

the assumption that the universe is expanding and that they have a common starting point, during the last 14 billion years, since plenty of thing scould have happened in that time