Dark energy is a much heard but little known topic. Read on to know what dark energy is and what happens as it takes on gravity as well as the energy from the big bang simultaneously.
The Big Bang
A fiery burst of energy in the middle of nowhere out of virtually nothing created our universe. We call this explosion, the big bang. it started from a point of infinitely small volume of infinitely high density. Think of all the matter in the universe contained inside a body of the size not of a star, planet, house, ant, atom or electron but even smaller than all of that. We don’t know exactly how small because our laws of physics break near that point. But we do know that it must be virtually non-existent.
If that sounds dramatic then that’s how dramatic an entry our universe has. It was the force from this explosion that spewed out all the matter and radiation that formed the universe as we know it. This matter still has an outward force associated with it, the one from the explosion, which keeps on pushing matter further outwards and thus the universe keeps on expanding.
But all space wasn’t created equal so some parts have greater density of matter that arose from this dot while others had less. The matter in places with greater density came together due to gravity and united to form greater bodies like nebula, stars and planetary systems. Other regions became what seem to be empty space as the little matter that was distributed randomly in these places got gravitationally attracted and moved towards places with high mass concentration (stars, planets, etc.).
In An Ever Expanding Universe
But even as particles in places came together, the universe as a whole kept on moving outwards because of the energy of the initial explosion. What this means is that space itself is expanding. Mars becomes more distant from the earth with time, the moon does the same, two trees on earth do the same and so do electrons and protons in an atom.
The one thing to remember is that all this happens because of the energy provided by the initial explosion. What’s more is that even as the energy of the big-bang moves everything apart, gravity is pulling everything together. The energy from the big-bang must get exhausted at some point of time just as the energy from a grenade explosion gets exhausted and gives way to gravity that pulls everything to the ground. This pulling by gravity when there is no other force acting on the body is known as free fall.
So the deal is, energy from the big bang will get exhausted one day and then all matter in the universe will be in free fall. Where will they fall? Towards each other. which means that all matter will come closer and closer together until they all come to one point in space and time. This will be the end of the universe and is given the name : the big crunch.
Something’s Missing, Dark Energy?
Now is the time for a little detour. If you remember from you school’s physics class, All physical bodies remain in a state of uniform rest or motion unless acted upon by an external force. We thought we knew these forces: one is the force from the big bang explosion and the other gravity. Therefore the predictions from the above theory must apply to our universe.
At least that’s how it was thought to be until 1998 when observations from the Hubble telescope garnered evidence of an accelerating universe. It became evident that the expansion of the universe was not slowing down as it ought to be according to the aforementioned theory. Everything in the universe was drifting apart from everything else at an ever increasing rate. This was very confusing territory to be in.
If the cosmos is accelerating outwards then there must be some force acting in that direction. And if there is a force making space stuff move then there must be an energy because again from school, energy is force times displacement.
This energy that seems to counter gravity and accelerate the universe outward, is known as dark energy. It still has us in the dark about its nature and origin.
If you are curious about the physical world and want to know more. Check out other articles from the author.