Go to the website for the JINA Center for the Evolution of the Elements and watch the animation of Big Bang nucleosynthesis (http://www.jinaweb.org/movies/bangmovie.html). What are the major stages after the Big Bang? What elements are created? Why are heavier elements not created?

The Big Bang marks the beginning of our universe. Immediately after this event, the universe went through several critical stages that set the foundation for everything we see today. It all started with the initial expansion, known as the inflationary epoch. During this phase, the universe expanded at an incredible rate, smoothing out any irregularities.
As the universe continued to expand, it cooled down, allowing quarks and gluons to combine and form protons and neutrons. This era is called the quark-gluon plasma stage. These particles further combined during a stage known as nucleosynthesis, leading to the formation of simple atomic nuclei. Key stages to note include:

• Initial inflation
• Formation of protons and neutrons
• Combination of particles to form nuclei

Each stage was essential in transitioning from a hot, dense state to a cooler universe where complex structures could eventually form.

Big Bang nucleosynthesis was a critical period in the early universe, during which the first elements were formed. This process primarily created the lightest elements through a series of nuclear reactions as the universe expanded and cooled. Specifically, hydrogen and helium were the primary products, forming in significant amounts.
Here are the main elements formed during Big Bang nucleosynthesis:

• Hydrogen: The simplest and most abundant element.
• Helium: Stability of helium-4 nuclei made it the second most abundant element.
• Traces of Lithium and Beryllium: Small amounts of these heavier light elements were formed, but in much smaller quantities.

The process of nucleosynthesis was efficient in producing these light elements due to the high temperatures and densities present at the time.

While Big Bang nucleosynthesis was effective at creating light elements like hydrogen and helium, it was limited in producing heavier elements. There are several reasons for this limitation. The universe expanded and cooled too quickly for the conditions necessary for heavier element formation to last.
The primary reasons why heavier elements were not formed are:

• Rapid Expansion: The universe expanded so quickly that there wasn't enough time to fuse nuclei into heavier elements.
• Cooling: As the universe expanded, it cooled down rapidly, making it difficult for nuclear fusion to continue.
• Insufficient Density and Temperature: The conditions required for building heavier elements, such as carbon and oxygen, were not met due to the falling temperatures and densities.

Later in cosmic history, heavier elements would form in the cores of stars through stellar nucleosynthesis, where conditions of extreme pressure and temperature allow for the creation of elements heavier than beryllium.