Because everything we have ever observed in nature follows the exact same pattern: 1. Single instable thing exists that tends to combine with other items to fo

Because everything we have ever observed in nature follows the exact same pattern: 1. Single instable thing exists that tends to combine with other items to form a somewhat stable object 2. The results combine with other more complex things in the same manner to create something else It's like a recursion. Something simple gets executed over and over again, each time gaining in parameters and complexity.