Why the Universe Exists: Antimatter, CPT Symmetry and CERN’s Antimatter Experiments

In this New Scientist documentary, the story of antimatter unfolds from the early universe to CERN’s antimatter factory. Scientists explore why matter survived the Big Bang by hunting for a tiny asymmetry between matter and antimatter and testing fundamental symmetries with ever greater precision.

• Big Bang asymmetry: for every billion antimatter particles, there were roughly one more matter particle, enabling a universe full of matter.
• Antimatter production and storage: CERN’s facilities create antiprotons, slow them, and trap them in Penning traps for precision measurements.
• Testing CPT symmetry: comparing properties of protons and antiprotons to exquisitely small uncertainties to probe fundamental laws.
• Moving antimatter off-site: BASE aims to transport trapped antiprotons to ultra-quiet labs to reduce environmental noise and improve measurements.

Introduction: The paradox of antimatter

The video opens with the paradox of existence: according to theory, the Big Bang should have produced equal amounts of matter and antimatter, yet our visible universe is dominated by matter. A tiny asymmetry—about one extra matter particle per billion pairs—gave rise to galaxies, stars, and life as we know it. The challenge is to understand where this imbalance came from, and whether antimatter behaves exactly like matter.

Chapter 2: The biggest science experiment on Earth

The narrative moves to CERN, the birthplace of particle physics, where antimatter can be created, slowed, captured and studied. Antiprotons are produced when protons from the Large Hadron Collider strike a metal target, producing a range of particles, among them antimatter. Experiments like LHCB probe the structure of matter and the role of antimatter in the early universe.

Beyond theory, the video shows the nuts and bolts of antimatter production: decelerating antiprotons, distributing them to different experiments, and catching them in traps for high-precision measurements. The goal is to understand antimatter’s properties, how gravity affects antimatter, and whether any tiny deviations from symmetry exist.

Chapter 3: The antimatter factory and Penning traps

Inside CERN’s antimatter factory, seven different experiments explore antimatter properties, from how antimatter absorbs light to gravitational behavior. A Penning trap uses magnetic fields to confine antimatter and prevent contact with ordinary matter, enabling precision studies of antiprotons and antihydrogen. A key observation technique, image current detection, records the oscillation of trapped antiprotons as they induce tiny currents in surrounding electrodes. The section highlights the scale and precision of modern antimatter research, where even nanogram-scale amounts matter for fundamental physics.

Chapter 4: Are matter and antimatter truly identical?

The program delves into CPT symmetry, a cornerstone of the Standard Model, which posits that particles and antiparticles should have identical masses and lifetimes if charge, parity, and time are inverted. Base conducts measurements to compare proton and antiproton properties with extraordinary precision, currently approaching parts-per-trillion levels. Alpha, another CERN experiment, studies antihydrogen and compares it to hydrogen, pushing the limits of how closely antimatter mirrors ordinary matter while highlighting the immense technical challenges involved.

Chapter 5: Antimatter on the Autobahn

The BASE experiment takes a bold step: transporting decelerated antiprotons outside the noisy environment of CERN in purpose-built transport systems with cryogenics and magnetic shielding. The goal is to reduce background noise and achieve more sensitive CPT tests. The segment illustrates the practical challenges of moving antimatter safely and the engineering feats required to maintain trap conditions during transit.

Chapter 6: The wider hunt for the missing antimatter

The video broadens its scope to other global efforts searching for signs of asymmetry, including neutrinoless double beta decay and Majorana neutrinos, which could connect the neutrino's nature to matter-antimatter production in the early universe. The neutrinoless decay would reveal physics beyond the Standard Model and provide a crucial clue to why matter dominates antimatter today.

Conclusion: Pushing the boundaries of knowledge

The documentary frames antimatter research as a path to the deeper question of why anything exists at all. Each particle collision, precision measurement and lab-driven test amplifies our understanding and narrows the space for speculative theories about the universe’s origins. The future of antimatter research includes offline labs, even quieter environments, and continued experimentation that could reveal new physics or tighten CPT symmetry bounds even further.