Question: ?What is the universe made off? and ?How big is the universe?

Stewart Martin-Haugh answered on 12 Nov 2018:

Good questions!

As far as we know, the universe is made of three things:

1)Matter and light, like the atoms and light we see around us (about 5%)

2)Dark matter (like normal matter but doesn’t reflect light) (about 26%)

3)Dark energy (a mysterious substance that keeps the universe expanding) (about 69%)

We don’t know if dark matter is a particle, but we are trying to detect it on Earth. The experiment I work on, the Large Hadron Collider, is trying to create small amounts of dark matter, but we haven’t found any yet.

We don’t know what dark energy is either. But the equations we have for the universe, and all the observations through telescopes, work well with these three ingredients.

In terms of how big the universe is, we often talk about the observable universe. This is how far light has travelled from where we are now (i.e. Earth) starting from the Big Bang, when everything was together at one tiny point. Since we think nothing can travel faster than light, we cannot observe anything that’s further away than that. So we don’t know if the universe is bigger than this.

The exact number is 93 billion light years: the time light travels in 93 billion years. This is longer than the age of the universe but the universe is also expanding, making the distance larger.