Birth of Universe

Universe consists of many galaxies, millions- billions of stars and planets. Our own planet earth is like a grain of sand in the vast ocean (universe) floor. Many of us often think that how our planet was born or how our solar system was born. This is indeed a very interesting and fascinating question. Just think how much energy is required to produce this huge amount of masses (planets and sun) or vice versa how much mass is required to produce such enormous amount of energy (imagine the amount of energy produced by sun everyday). If you are not such a science geek then let me remind you that there is a very popular theory proposed by Albert Einstein known as mass energy relationship (E=mc^2).

If this is not enough then let us think of something more bigger(or the biggest!)-How the whole universe came to existence??
Still, we do not have a definitive answer for this. But indeed we have few hypothesis. Among these the most famous (or most probable) are:
1) Big Bang Theory
2) Steady State Theory

But before indulging into these topics more deeply let us try to identify the constituents of our universe (only brief description!). Our universe mainly consist of:

a) Stars- these are the shining members of our universe. Actually, the stars emit their own light. That means they produce their own energy(Basically heat and light energy). And how they produce it?? The answer is Nuclear Fusion.
E.g.- our own Sun.

b) Planets- The best example is our own planet earth. Planets are heavenly bodies that revolve around stars (due to gravity).

c) Natural Satellites- Like our moon. These natural satellites revolve around planets but they do not have their own energy.( Moon appears to glow only because it reflects sunlight).

Apart from these their are other heavenly bodies also like asteroids, comets, meteors, etc. We will discuss about them later, because as of now we are talking only about birth of universe.

So, let us go back to our hypothesis, namely Big Bang and Steady state.
Among these two, Big- Bang is more popular and is accepted by most physicists and cosmologists. It is supported by most comprehensive and accurate scientific observations and evidence.
On the other hand, Steady State theory is a model developed in 1948 by Fred Hoyle, Thomas Gold, Hermann Bondi and others as an alternative to the Big Bang theory. But this theory has very less number of supporters as compared to Big-Bang theory.

As the name suggests, Big-Bang is about one big explosion whereas steady state refers to one static universe(it has no beginning and no end). We will discuss these two topics in more detail in my subsequent posts.