Big Bang: Is It Really An Explosion?

One of the most high up interpretations of the Big Bang is that it’s just an “explosion”. Now that gets us to the big question: was it really one?

The correct answer would be a NO. Let’s hear it. It was NOT an explosion, rather an expansion. Expansion of matter in space as well as the expansion of space itself.

To explain it further, we ought to know what an explosion is.

According to Wikipedia, “An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases.”

Now here’s another question: when do we say something is “released”? For instance, when do we say a prisoner is released? Only when there’s something outside of the prison and the prisoner is free to dwell there. By the definition of the universe, it’s all that exists, and there’s nothing beyond, or outside of it. Then where could this energy possibly be released? So that’s one aspect of the Big Bang which fails it as an explosion. Is that it? No, there’s more.

Consider the law of conservation of linear momentum. It states that the net linear momentum of particles in a system is always conserved in absence of an external force (momentum is mass times velocity). For an explosion, this law ought to hold good.

Here’s a brief explanation.

Let’s say a bomb explodes to 2 fragments of equal mass. According to the law of conservation of linear momentum, the net momentum before the explosion must equal the total momentum after the explosion. Now the velocities of both the fragments before the explosion are obviously zero.

We can hence assert that their net velocity after the explosion must also be zero. That’s possible only when the velocities are equal in magnitude but opposite in direction. In other words, the 2 fragments are spewed in opposite directions with identical speeds.

So if at all Big Bang was an explosion, the law of conservation of linear momentum held good. Now that’s the problem. Words like ‘mass’ or ‘momentum’ lacked meaning until the first picosecond after t = 0, or the Big Bang. The universe had already expanded (exponentially) by then.

If that doesn’t convince you, let’s assume that particles had mass right through t = 0. If the big bang had really been an explosion, all those “particles” would have been uniformly distributed in the universe, and nothing like stars or galaxies would form

We’re forced to ignore the effect of dark matter: they’re nothing but internal forces. There’s no ‘external‘ to the universe, so there are no ‘external forces’.

So the explosive big bang calls for a universe with no stars or galaxies, which obviously sounds ridiculous.

With all this, we say that the Big Bang was not an explosion. It’s rather an expansion: expansion of matter in space, and the expansion of space itself. With the explosion out of the picture, one can’t assert that the second law of thermodynamics (which says the randomness or chaos (or entropy) in the universe always increases with time) forbids the Big Bang.

It’s argued by many, that the randomness at the big bang (considered an explosion) is supposed to be much higher than the same in the universe, 13.7 billion years later, which is a clear violation of the second law, hence concluding the Big Bang ‘wrong’.

Now that we know it was not an explosion, we can be pretty sure that the net randomness in the universe at the Big Bang may very well be lower than that of the universe right now.

<sub>Image Credits:
1. Pixa Bay 2. Medium 3. Wall Devil</sub>