The Formation of Planets: The Role of the Big Bang in Our Solar System

We often ponder how the Big Bang, which occurred 13.77 billion years ago, could have created the planets we see today. However, the Big Bang did not directly create the planets. Instead, it set the stage for their eventual formation through the processes of gravitational accretion and conservation of angular momentum.

Understanding the Time Scale

The Big Bang marks the beginning of the universe, but the formation of our planets happened much later, around 4.5 billion years ago. This significant time gap (roughly 9.27 billion years) represents the time it took for the universe to cool, gather enough matter, and form structures that would eventually become our solar system. It's similar to asking how New York City's foundation led to the construction of the Empire State Building. The city's establishment was necessary, but not the direct cause of that building's construction.

The Process of Planetary Formation

The formation of planets began with a massive gas and dust cloud, known as the solar nebula. This proto-planetary nebula was made up of mostly hydrogen and other elements. Over a long period, this mixture slowly started to draw in more matter from the surrounding space. As the nebula began to spin, it drew in even more material. A proto-star started to form in the center, surrounded by rotating material that gradually condensed into smaller bodies. This process took about 600 million years to form the planets and moons we know today.

The Role of Gravity

Gravity played a crucial role in the formation of planets. Even in the vastness of space, gravitational forces were at work, pulling materials together to form larger and more distinct bodies. Larger clumps of material, such as those creating galaxies, stars, and planets, could be observed. Micro clumps, such as asteroids and comets, continued to form through this gradual accumulation process.

Theoretical Perspectives

Many people might wonder if there is a 'theory of the Big Bang' in the sense that it explains the origin and evolution of the universe. The Big Bang is an observable feature of the universe, specifically its expansion and the fact that it was smaller in the past. Though early physicists like Georges Lema?tre and Albert Einstein theorized and observed certain aspects of the Big Bang, the idea is now much better established. In the context of cosmology, the term 'Big Bang theory' often refers to the general understanding and explanation of the Big Bang within the framework of the General Theory of Relativity.

According to General Relativity, the large-scale processes of the Big Bang lead to the formation of structures like galaxies and stars. For the formation of planets, however, the specific theory of planetary accretion and the conservation of angular momentum from Newtonian physics provide the necessary explanations. This is often described as gravitational accretion. The detailed processes of gravitational forces bringing together small bits of matter and conserving the angular momentum of the spinning mass are the key to understanding how planets formed.

It's important to note that even with General Relativity, for the scale and masses involved in planetary formation, the simpler Newtonian mechanics suffice to describe the processes accurately. Therefore, the question is more accurately framed as, 'how do solar systems form according to the General Theory of Relativity?' and the answer is that it involves gravitational accretion and conservation of angular momentum within the framework of those simpler gravitational laws.

Conclusion

In summary, while the Big Bang initiated the cosmic event that laid the foundation for the universe, the actual formation of planets is influenced by gravitational accretion and the conservation of angular momentum. Understanding these processes helps us better appreciate the complexity and organization in our solar system, rooted in the fundamental principles of physics.