This article notes that a Big Bounce cosmology implies exquisite fine-tuning.
Cosmology is the historical science of the whole universe and emphasizes theories on the origin of the universe. Cosmology itself has a history of tried and passed theoretical fashions. As this article points out, the fashions have progressed somewhat in this way:
- God created the universe vs the universe is eternal and uncreated (both of these go back to before cosmology began).
- Steady-state theory.
- Big bang theory.
- Big bounce theory.
- Multiverse theory.
The theory of the eternal universe was invalidated by the discovery of redshifts among other scientific evidence. Steady-state theory and big bounce theory are both widely considered disproved. The big bang theory remains the mainstream view, with wide acceptability of the multiverse theory as well.
While the multiverse theory is in many ways unfalsifiable and therefore unscientific, it is compatible with the big bang theory which is scientifically evidenced. It is also the fashionable view today. God having created the universe is viewed as unscientific.
Even though the big bounce is widely considered disproved by scholars it is still at times invoked in the context of philosophical debate as a rebuff to the class of ideas including the anthropic principle, teleological argument, argument from fine-tuning, and so on.
One point I haven’t heard often made is the point that an infinite bounce is an example of an extremely rare or impossible thing which indicates design. An ordinary ball when dropped will only bounce a few times then stop bouncing. No ordinary ball would endlessly bounce. For a ball to bounce infinitely would require putting that ball in a very special context. Maybe some sort of special gravity vacuum thing I don’t know.
Perhaps an observable mechanism which better represents an infinite cycle would be a pendulum. In theory a perfect pendulum can swing forever, but in practice they don’t, because construction of the perfect pendulum is basically impossible, as well as other problems including as air friction and such. Even a poorly made pendulum is still a carefully designed thing. I have never seen a pendulum absent of design.
In conclusion, while the big bounce fails on its own scientific merits, even if had stood it would only have been another example of fine tuning.