Suppose that 0.7% were 0.6% instead ... |
Then the bonding of hydrogen nuclei in the first step of the Sun's fusion chain would be too weak and unstable!
The whole universe would consist of hydrogen atoms!
No stars ... no planets ... no other elements!
Suppose that 0.7% were 0.8% instead ... |
Then the bonding of hydrogen nuclei in the Big Bang nucleosynthesis would been too strong! All of the hydrogen would have been used up to form heavier nuclei!
There would be no hydrogen fuel to allow stars to burn, no water to support life!