Dark Matter/Energy.

"The Universe is made mostly of Dark Matter and Energy, and we don't know what either of them is made up of." - Saul Permutter

Imagine everything you know, literally everything. Now, pile it up and then then times it by about 10 billion. Imagine every piece of matter in our universe, literally every galaxy to planet. 

Guess how much matter this makes up of our universe? 4%. (Approx 0.4% stars etc, 3.6% interstellar gas)

Dark matter. 23% of our Universe. Still this isn't much.

Dark energy takes up the rest, 73%.

What is dark matter? Well...

We don't know, thats the simple answer.

All we know is that it's an invisible source of matter that has mass, and has a gravitational affect on matter.

Put it this way, imagine you have a bowl of cereal, and its nearly empty- only a few 'Corn Flakes' left. If you stir your milk, all the corn flakes move around the centre, at their own accord, at different speeds - right? Well this should happen with our galaxy, but...

It doesn't.

Imagine you have a CD. Draw 100 billion dots on the CD and spin it. They all move at the same speed at the same time right? This is what dark matter does to our galaxy.

"Well thats easy, we should be able to find it."

Well... its not that simple. They're non-baryonic. Invisible, and basically undetectable. A nobel prize is waiting for anyone to make a break through in this field, which I wish to pursue in the future.

Whats dark energy then? Well scientists noticed the expansion of our universe is not carrying on, but accelerating. Dark energy is a substance that does the opposite of dark matter.

It pushes galaxies apart.

The further apart two galaxies are, the less gravity is affecting them (from the other galaxy) and thus, dark energy is affecting them more. So the expansion of the universe is accelerating, getting faster year by year.

To conclude, what is the fate of our universe? Will we eventually hit a wall and return to one small point? Or will we just keep on going until every star dies out, and the universe is cold and dark? Or will nothing happen? Whats your opinion? I know mine.

Thanks for reading, Ben.