Another testimony to the big bang theory is the discovery of the large number of "light elements" Hydrogen and Helium found in the universe. The amount of helium in particular is the most coincidental to the big bang theory. Most of the other theories suggest a much smaller amount of Helium. Most scientists believe that the percentage of Hydrogen and Helium has remained the same since the big bang so this should explain the current ratio of hydrogen and helium. 3 seconds after the event when the universe was billions of degrees in temperature protons and neutrons were produced in exact numbers. The neutrons however decayed at a faster rate but because the universe was expanding the neutrons combined to form deuterium and helium. This halted the neutron decay.
The abundance of hydrogen and helium helps scientists understand the universal expansion rate. The scientists believe that if the universe had expanded any faster there would have been more stable neutrons and thus more helium; if it had expanded slower however the temperature would have been much hotter resulting in more unstable neutrons and therefor less helium.
The abundance of hydrogen and helium helps scientists understand the universal expansion rate. The scientists believe that if the universe had expanded any faster there would have been more stable neutrons and thus more helium; if it had expanded slower however the temperature would have been much hotter resulting in more unstable neutrons and therefor less helium.