Today, Tuesday October 27, I was fortunate to take a tour of CERN, the European Organization for Nuclear Research in Geneva, Switzerland and the world’s largest particle accelerator laboratory!
Scientists from all over the world use CERN to study the building blocks of matter and uncover the secrets of the universe by colliding particles in a particle accelerator at 99.9999% the speed of light! Yes, those four 9’s after the decimal are precise. CERN is the home of the Large Hadron Collider (LHC), where particles are sent down an approximately 15-mile-long underground tunnel that is kept under conditions found in deep space: in a vacuum at nearly -370°K. For comparison, the entire city of Chicago is roughly 10 miles wide.
Our tour included a lecture about the history of CERN, a visit to one of the four main experiments collecting data, and a descent 100 meters underground (about a football field) where the experiments and the particle accelerator ring are located. The experiment we visited was called LHCb and it was looking for a particle called the “beauty quark”. The underground facility was about the size of a small office building! It had some of the worlds most powerful magnets and a huge array of detectors that are activated when particles slam into them. I couldn’t believe the number of individual parts, wires, circuits, magnets and components.
I was extremely excited about this visit for two reasons. First, because I work for Mozilla, the worlds most committed and successful defender of a free and open web. In fact, that very same web was invented in 1989 by Tim Berners-Lee, an English scientist at CERN! That’s right, all of the code and concepts for the World Wide Web (W3) was created at CERN and the world’s very first website is still hosted at it’s original location there. The second reason I am so excited is because I earned my PhD in Astrophysics and the study of Cosmology: the size, age, composition, history and future of our entire universe. Even though the experiments, detectors and facilities at CERN are focused on tiny particles, here on Earth, the work they are doing is actually very important to our understanding of the entire universe. Let me explain.
Humans have always created stories about our universe to explain where it came from and our part of it. However, modern scientific theories and cutting edge technology have enabled us to explore and interpret our discoveries like never before. Our modern cosmological theory emerged over the last 100 years. It is a scientifically supported story of our universe that relies on two of our greatest physical theories combined. It is a story of the very large and the very small.
Einstein’s theory of gravity – general relativity – tells us about the largest qualities our universe: its size, shape, and composition. This theory describes how large quantities of matter and non-matter, like stars, galaxies and the light flowing throughout space, can influence the shape of the universe. In return, the shape of the universe, or it’s curvature, can influence the way that matter and light moves around in it. Using general relativity we have predicted and measured warps in space-time that bend light around planets, slow down the time experienced by space travelers, and detected rips in the very fabric of space-time known as black holes.
The other theory is quantum theory. It describes the behavior and interaction of the very smallest particles that reside in our universe; the building blocks of matter. The particles that obey quantum theory are atoms, their protons, neutrons and electrons, and an entire zoo of other particles: quarks, neutrinos, bosons, and photons. It’s an exotic and mind-bending theory that questions the very meaning of reality. In quantum theory, the position and energy of a particle is always uncertain until it interacts with something else. Particles are a bit like ghosts until you slam them together.
The Evolution of the Expanding Universe
All Matter is Composed of Atoms and Other Light Particles.
So what can these two theories have in common? Well in our universe today, these theories don’t get used together very much. But the universe of the past was a very different place.
One of the most striking discoveries that we have made in the last 100 years is that the universe is expanding! There is a lot of astronomical evidence for this bizarre fact, collected from the light of exploding stars in distant galaxies. The evidence of an expanding universe is explained by general relativity and it predicts some remarkable things. The most important prediction is that if the universe has always been expanding, then if we run the clock back and reverse time, the universe shrinks.
Let me take a little break here and add an important point. An expanding universe doesn’t mean that the universe is actually getting any bigger. Based on what we have been able to learn, the universe is actually probably infinite in size, and infinity plus one, is still just infinity. So when we say that the universe is expanding, we mean that the distance between two points in space gets bigger. When it is shrinking, we mean that the distance between two points gets smaller. If it took you an hour to get to grandma’s house today and then the universe expanded by two, it would take you two hours to get to grandma’s house. But the universe would still be infinite.
So, here’s the thing about a shrinking universe. In a shrinking universe, the space between any two particles gets smaller. In a universe full of particles, which is shrinking, all of the particles get closer together. The universe becomes denser. Steel, water and air have different densities. Steel is the densest, water less dense, and air the least dense. This is why steel sinks in water; air bubbles rise and expand out of water; and steel ships filled with air can float on the ocean. So a shrinking universe gets denser.
However, a shrinking universe doesn’t turn into a dense metal, or anything solid like that. This is because the particles spread out in the universe actually have a lot of energy. So when you start bringing them closer together, they ram, slam and collide into each other more often. Particles exchanging energy is actually the basis of temperature. So as we run the clock back, and the universe shrinks, it gets hotter and denser. How hot and dense does it get? Hotter and denser than the center of stars. This is the Big Bang Theory, and it isn’t actually about an explosion at all. It is about the hot, dense, early universe, which has expanded into the universe we live in today.
So, because the Big Bang Theory is all about colliding particles in the early universe and experiments at CERN like the LHC create epic collisions between particles, scientists at CERN actually work to recreate the conditions of the early universe! CERN allows scientists to explore the very limits of the quantum theory of our universe better than any other facility on Earth. In fact, it’s probably about the best that we can do on Earth to make those measurements.