Zhao Yi felt like he had joined some sort of cult.
"Come, come, join the cult!"
"Welcome, newcomer!"
"At last we have another companion who shares our beliefs!"
Come to think of it, it made sense.
Theoretical physics is like that. Believing in a certain theory is really like having a faith, whether it be Supersymmetry, Grand Unification, String Theory, or Multiple Universes...
Each one cannot be proven in a short time, but can give birth to a school of thought.
The Big Bang Theory, widely popularized and known even by elementary school students, talks about the expanding distances between galaxies or the observable remote parts of the universe measuring so and so many billion light years. However, using these conditions to indicate that the universe is expanding is clearly insufficient.
The Big Bang is, after all, only a doctrine of theoretical physics.