We exist because of a mistake. Or rather, for a small imperfection. Isn't it poetic to think that everything we know (from stars to mountains, from dogs to ham sandwiches) is here because something between matter and antimatter didn't work as expected? And yet that's exactly what scientists at CERN they are trying to prove to us, with an almost touching obstinacy.
The latest chapter in this research comes from La Thuile, in the beautiful Aosta Valley, Italy, where physicists have announced that they have finally observed a subtle but significant asymmetry in the behavior of particles called beauty-lambda baryons and their antimatter twins. A small difference that could explain one of the greatest mysteries of the universe: why we are here, rather than not at all.
The Mystery of the “Complicated Relationship” Between Matter and Antimatter
According to everything we know about physics, the Big Bang should have produced matter and antimatter in exactly equal amounts. A nice little housewarming party for the universe with equal numbers of guests for both sides, so to speak. Yet, look around you: antimatter has essentially “disappeared,” while matter has formed everything we see today. From galaxies to planets, from morning coffee to kittens on the web, everything is made of matter.
I like to think of this situation as a cosmic election where one of the candidates won with 100% of the vote. A result that would raise more than one eyebrow among international observers, don't you think? Nature, evidently, is not a great democrat.
When particles break the mirror
The explanation for this apparent cosmic injustice may lie in something called “CP violation.” Imagine a perfectly symmetric universe, where every particle has a twin antiparticle with exactly the opposite characteristics. If you looked through a mirror and reversed all the electric charges, the laws of physics would appear exactly the same. This is what physicists call “CP symmetry.”
But nature, with its usual penchant for ruining beautiful theories, has decided that this symmetry is not sacred. Particles and antiparticles do not behave exactly the same, and this small difference may have tipped the balance in favor of matter in the first moments after the Big Bang.
Antimatter, as far as we know, is nothing more than matter with a minus sign in front of it. Like that relative who always does the opposite of what you tell him, on principle. Fascinating in theory, but rather uncomfortable to have around, especially if you care about your molecular integrity.
The breakthrough in beauty-lambda baryons
Until now, CP violation had only been observed in mesons, particles composed of a quark and an antiquark. Vincenzo Vagnoni, spokesperson forLHCb experiment held on March 24th, explains why it took so long to observe the same phenomenon in baryons:
“The reason it took longer to observe CP violation in baryons than in mesons is due to the magnitude of the effect and the data available. We needed a machine like the LHC capable of producing sufficiently large numbers of lambda-beauty baryons and their antimatter counterparts.”
Il baryon bottom lambda (also called “beauty”) It's like a heavier, shorter-lived cousin of the protons and neutrons that make up atoms. It's made up of an up quark, a down quark, and a beauty quark. I know, particle physicists aren't great at naming things in a nutshell, but they make up for it with mathematical precision.
You know when you meticulously count your receipts to figure out where your money went at the end of the month? Well, the physicists of CERN They did something similar, but with subatomic particles. They analyzed huge amounts of data collected by the LHCb detector during the first and second runs of the LHC (2009 to 2013 and 2015 to 2018), looking for differences in the way lambda-beauty baryons and their antimatter twins decay into lighter particles.
The Numbers That Change Everything in the Dance Between Matter and Antimatter
The discovery is subtle, but significant: the difference between the number of Λb and anti-Λb decays, divided by the sum of the two, differs from zero by 2,45%, with an uncertainty of about 0,47%. Statistically speaking, the result differs from zero of 5,2 standard deviations, exceeding the threshold necessary to affirm the existence of CP violation in this baryonic decay.
For the uninitiated, it's like noticing that in a perfectly shuffled deck of cards, the red cards come out slightly more often than black ones. A difference so small that you might not notice it in a poker night, but it becomes evident if you play enough hands. And when it comes to the universe, even the smallest asymmetry can have enormous consequences when multiplied over billions of years.
I like to imagine the early universe as a giant cosmic ballroom, where particles and antiparticles dance frantically, annihilating each other when they meet. If the dance were perfectly symmetrical, there would eventually be no one left on the floor. But that small imperfection in the choreography left some matter dancers without partners, forming everything we see today. A providential misfortune.
Beyond the Standard Model with Matter and Antimatter
The most intriguing thing is that even this CP violation, although confirmed, is not enough to explain why the universe contains so much matter and so little antimatter. Standard Model of Particle Physics, our best attempt to describe how the universe works at the subatomic level, predicts a CP violation too small to account for the observed asymmetry.
This suggests that there may be new sources of CP violation beyond those predicted by the Standard Model, the search for which is an important part of the LHC physics program and will continue in its “successors”.
Joachim Munich, Director of Research and Computing at CERN, comments:
“I congratulate the LHCb collaboration on this exciting result. It once again underlines the scientific potential of the LHC and its experiments, and provides a new tool with which to explore the matter-antimatter asymmetry in the Universe.”
Elementary particles, the hunt continues
The search, you may have guessed, is far from over. Scientists will continue to search for further evidence of CP violation in other particle systems, hoping to build a more complete picture of how the asymmetry between matter and antimatter has shaped the universe.
I like to think that we are finally starting to understand why we exist, rather than not exist at all. No small matter, considering that most of us spend more time worrying about the latest smartphone update than reflecting on how lucky we are to exist.
Because yes, we can be content to know that we exist thanks to a mistake. But what a magnificent mistake it was. Without it, we wouldn’t be here to tell the story. And certain comments on social media wouldn’t exist either, which, if you think about it, might not have been such a great loss.
