It can be difficult to understand something very large or very small.Ron Koebeler/Millennium Images, UK
Imagine taking off in a spaceship that can travel at the speed of light. I can’t go far. It also takes 100,000 years to reach the other side of the Milky Way. Our nearest galactic neighbor, Andromeda, is another 2.5 million years away. And beyond that, there are about 2 trillion galaxies.
The vastness of the universe is difficult to comprehend. But fundamentally, the universe is made up of tiny particles. “The universe is a bit foreign, both small and very large,” says the particle physicist. Alan Barr at Oxford University. “I don’t think I really understood it, I just got used to it.”
Still, you need some sense of scale to have a chance of understanding how reality works.
Let’s start with the cosmic microwave background radiation (CMB). This is radiation released 380,000 years after the Big Bang. “The largest scale we have measured is a feature of the CMB,” says astrophysicist Pedro Ferreiraalso at the University of Oxford, which allowed them to estimate the diameter of the observable universe to be 93 billion light years.
At the other end of the scale, the smallest entities are fundamental particles like quarks. However, quantum physics depicts these as sizeless, dimensionless blips in the quantum field. So, what is the shortest distance? The maximum value we can do is the so-called Planck length, which is approximately…
