Every new generation of scientists pushes against the limits of what we know about the universe, and when they do so it always seems to become more vast.
Early humans no doubt once thought that the river valleys in which they lived were all that there was in the universe.
Thousands of years later, we believed that the Earth lay at the center of the universe, until we discovered that it was one planet among many around our Sun.
In the 17th Century, we found that our Sun was one among billions of others just like it in the Milky Way galaxy.
In 1923, we discovered that the Milky Way was one among billions of galaxies, who outnumber every human being who has ever lived.
So the universe is extraordinarily bigger than we thought. From a certain perspective, history could be organised into a series of thresholds where we discover that our ‘everything’ is just a tiny part of a much grander whole.
But it has become apparent that the very substance that we are made of also contains thresholds. Not only is the universe bigger than we thought, but it’s also stranger.
We are all made of a substance that scientists call ‘matter’. It means that everything from moon rocks to London busses are made up of molecules, which are made up of atoms. Atoms are made from quantum mechanical particles like quarks and gluons.
But in the late 20th Century, cosmologists discovered that there was more in the universe than just matter. There are new, strange forms of energy that exist around us at all times, though they are invisible and travel straight through us like ghosts.
What’s more, when they estimated how much of the universe was ordinary matter and how much was these unusual new forms, they discovered that most of the energy in the universe belonged to what they now call dark matter and dark energy.
Matter was renamed into ‘Ordinary matter’ or ‘Normal matter’ to distinguish it from these other forms.
Of course, ordinary matter has its own extraordinary thresholds, and the deeper we look, the more layers we uncover. For example, it’s theorised that quarks and other quantum mechanical particles are actually made up of tiny, one-dimensional things called strings.
The discovery of so many layers of reality that are beyond our direct experience is very unintuitive for us. Our sensory perception of the universe is fundamentally limited by our biology that evolved to detect our immediate surroundings, not distant galaxies or the fundamental structures of reality.
We can imagine our senses as a lantern illuminating of a tiny part of an immense, pitch-black cavern. Our progress has come from building ever more elaborate instruments that cast a more powerful light, like the telescope, microscope, space telescopes, and hadron colliders.
Almost always, what they reveal are more frontiers of the limitless creativity of the universe.