Latest news with #matter
The Independent
6 days ago
- Science
- The Independent
Scientists make antimatter discovery that could unlock secrets of big bang
Why didn't the universe annihilate itself moments after the big bang? A new finding at Cern on the French-Swiss border brings us closer to answering this fundamental question about why matter dominates over its opposite – antimatter. Much of what we see in everyday life is made up of matter. But antimatter exists in much smaller quantities. Matter and antimatter are almost direct opposites. Matter particles have an antimatter counterpart that has the same mass, but the opposite electric charge. For example, the matter proton particle is partnered by the antimatter antiproton, while the matter electron is partnered by the antimatter positron. However, the symmetry in behaviour between matter and antimatter is not perfect. In a paper published this week in Nature, the team working on an experiment at Cern, called LHCb, has reported that it has discovered differences in the rate at which matter particles called baryons decay relative to the rate of their antimatter counterparts. In particle physics, decay refers to the process where unstable subatomic particles transform into two or more lighter, more stable particles. According to cosmological models, equal amounts of matter and antimatter were made in the big bang. If matter and antimatter particles come in contact, they annihilate one another, leaving behind pure energy. With this in mind, it's a wonder that the universe doesn't consist only of leftover energy from this annihilation process. However, astronomical observations show that there is now a negligible amount of antimatter in the universe compared to the amount of matter. We therefore know that matter and antimatter must behave differently, such that the antimatter has disappeared while the matter has not. Understanding what causes this difference in behaviour between matter and antimatter is a key unanswered question. While there are differences between matter and antimatter in our best theory of fundamental quantum physics, the standard model, these differences are far too small to explain where all the antimatter has gone. So we know there must be additional fundamental particles that we haven't found yet, or effects beyond those described in the standard model. These would give rise to large enough differences in the behaviour of matter and antimatter for our universe to exist in its current form. Revealing new particles Highly precise measurements of the differences between matter and antimatter are a key topic of research because they have the potential to be influenced by and reveal these new fundamental particles, helping us discover the physics that led to the universe we live in today. Differences between matter and antimatter have previously been observed in the behaviour of another type of particle, mesons, which are made of a quark and an antiquark. There are also hints of differences in how the matter and antimatter versions of a further type of particle, the neutrino, behave as they travel. The new measurement from LHCb has found differences between baryons and antibaryons, which are made of three quarks and three antiquarks respectively. Significantly, baryons make up most of the known matter in our universe, and this is the first time that we have observed differences between matter and antimatter in this group of particles. The LHCb experiment at the Large Hadron Collider is designed to make highly precise measurements of differences in the behaviour of matter and antimatter. The experiment is operated by an international collaboration of scientists, made up of over 1,800 people based in 24 countries. In order to achieve the new result, the LHCb team studied over 80,000 baryons ('lambda-b' baryons, which are made up of a beauty quark, an up quark and a down quark) and their antimatter counterparts. Crucially, we found that these baryons decay to specific subatomic particles (a proton, a kaon and two pions) slightly more frequently – 5 per cent more often – than the rate at which the same process happens with antiparticles. While small, this difference is statistically significant enough to be the first observation of differences in behaviour between baryon and antibaryon decays. To date, all measurements of matter-antimatter differences have been consistent with the small level present in the standard model. While the new measurement from LHCb is also in line with this theory, it is a major step forward. We have now seen differences in the behaviour of matter and antimatter in the group of particles that dominate the known matter of the universe. It's a potential step in the direction of understanding why that situation came to be after the big bang. With the current and forthcoming data runs of LHCb we will be able to study these differences forensically, and, we hope, tease out any sign of new fundamental particles that might be present.
ABC News
7 days ago
- Science
- ABC News
Large Hadron Collider glimpses clue in search for universe's missing antimatter
Scientists have uncovered another clue in the effort to solve one of the great puzzles of modern physics: why there is more matter than antimatter in the universe. The discovery relied on observations made with the world's largest machine, the Large Hadron Collider, which helps researchers to probe the fundamental nature of matter. Everything we see around us is made up of subatomic matter particles such as protons and neutrons, which belong to a category of particles called baryons. An experiment using the giant particle accelerator, based at CERN in Switzerland, has for the first time seen baryons form more matter than antimatter. The findings could change our understanding of how small particles interact and help explain the absence of antimatter, said Tom Hadavizadeh, a physicist at Monash University and collaborator on the project. "We haven't found the new physics yet, but it's given us a new way to look for it," Dr Hadavizadeh said. The researchers have published their findings in Nature. The current leading theory in particle physics — the Standard Model — predicts that for every particle of matter that forms, a corresponding particle of antimatter forms. Antimatter particles are identical to matter particles, but with their electrical charges reversed. Scientists have observed similar amounts of matter and antimatter being generated when they create subatomic particles by colliding larger particles at high speed around large underground loops in the Large Hadron Collider. But antimatter doesn't tend to stick around — if it collides with regular matter, both particles annihilate each other, releasing energy. If antimatter and matter were truly created in equal amounts, as per the Standard Model, the universe wouldn't exist. The problem for this theory is that the universe does exist, and it's mostly made of matter, with only tiny amounts of antimatter. This "matter-antimatter asymmetry" is a major unresolved problem in physics. "The way that we explain that is that at some point in the early universe, matter should have become slightly favoured over antimatter," Dr Hadavizadeh said. "There's this little excess that remains once most of the antimatter and matter annihilates away, and that little excess is what we see left over today." So where did this asymmetry between matter and antimatter come from? Ray Volkas, a physicist at the University of Melbourne who wasn't involved in the research, said that the Standard Model does have a way of explaining some of the matter-antimatter asymmetry. "It's been known since the early 1960s experimentally that there actually is a subtle difference in the way that matter and antimatter interact [with other particles]," Professor Volkas said. This subtle difference is called the charge-parity violation, or CP violation, and can help explain why there is less antimatter than matter. While researchers had observed this asymmetry in some smaller particles, they had not yet observed it in baryons — a type of subatomic particle made from three quarks. "Almost all of the matter that we come across is baryons," Dr Hadavizadeh said. The team of more than 1,500 scientists from 20 countries, called the 'Large Hadron Collider beauty' (LHCb) collaboration, used the giant particle accelerator to look for examples of asymmetry in baryons. They analysed libraries of data from the first few years of the experiment, looking specifically at curiously named "beauty" baryons. They were able to spot baryons decaying in an asymmetric way — generating more matter than antimatter. Professor Volkas says it is an "interesting result" but neither he, nor the LHCb researchers, think they've come close to solving the whole matter-antimatter mystery yet. "The amount of CP violation in the Standard Model is actually not sufficient to explain cosmological matter-antimatter asymmetry," Professor Volkas said. "It's one of the great mysteries of science." Matter-antimatter asymmetry is just one problem with the Standard Model. While it's beaten all the tests particle physicists have set for it over the decades, the theory has huge gaps in it. It also can't explain gravity or dark energy, a mysterious phenomenon thought to be behind the acceleration of universe expansion. "We don't want our theories to be totally wrong — in fact, they can't be because they work too well — but we want them to be incomplete so that we can add things," Professor Volkas said. He says the LHCb experiment, and similar ones, are getting increasingly thorough at scrutinising the matter-antimatter mystery. "What they're trying to do is examine this CP violation effect with ever greater precision to try to find if the standard theory continues to be verified, or if it will fail and we'll need to extend or modify the theory." While this new result is consistent with the Standard Model, the researchers suggest it might point towards places where they can move beyond the theory. Now that the researchers have measured the asymmetry in baryons, they'll be able to investigate this phenomenon more closely. The study potentially "unlocks a whole new set of particles" to observe new types of physics, Dr Hadavizadeh said.
New York Times
16-07-2025
- Science
- New York Times
New Clue to How Matter Outlasted Antimatter at the Big Bang Is Found
Understanding why matter and antimatter behave differently is key to understanding why there is a universe at all. Now physicists have discovered the latest example of a subtle difference between the stuff that makes up galaxies, stars, planets and us, and its evil-twin opposite. Particles of antimatter, like anti-electrons and anti-protons, possess the same mass but opposite electric charge as the usual electrons and protons. In a discovery published on Wednesday in the journal Nature, an international collaboration of scientists working at the CERN particle physics laboratory outside Geneva described an imbalance among particles that are cousins to the protons and neutrons that make up everyday objects. That makes the new observations 'very important for us to further understand bigger questions like the matter-antimatter asymmetries in the universe,' said Xueting Yang, a graduate student at Peking University who led the analysis. The Big Bang that created the universe should have produced equal amounts of matter and antimatter. When a particle of matter bumps into its antimatter counterpart, the two particles annihilate. Thus, all of the matter should have annihilated all of the antimatter in a cataclysmic burst of radiation, leaving an empty universe for eternity. And yet, 13.8 billion years later, you — made of matter, not antimatter — are reading this news on a device (or in a newspaper), which is also made of matter. Somehow, in the instant after the Big Bang, for each billion or so pairs of matter and antimatter, an extra particle of matter persisted. This slight tipping of the laws of physics toward matter is known as charge-parity, or CP, violation. Want all of The Times? Subscribe.
The Independent
04-06-2025
- General
- The Independent
Universe may have started inside black hole, not from Big Bang
The universe may not have begun with the Big Bang as is generally thought but from the collapse of a massive black hole, a new theory suggests. Current observations of our universe appear to support the Big Bang and cosmic inflation theories, which say that the early universe sprang into existence from a singular moment in space and time and rapidly blew up in size. The theories, however, leave many fundamental questions unanswered. For one, in the Big Bang model, the universe begins with a singularity, a point of infinite density where the laws of physics break down, making it difficult to understand what existed before the beginning. Two, after the explosion, the universe is said to have undergone accelerating expansion powered by yet unknown forces with strange properties. That is to say this model of cosmology explains the origin of the universe by introducing new forces and factors that have never been directly observed while still not explaining where everything came from. The new theory, described recently in the journal Physical Review D, probes what happens when the early universe's dense collection of matter collapses under gravity instead of tracing back how it all began. This is a process similar to what happens when stars collapse into black holes, but exactly what is inside these dense cosmic entities remains a mystery. Current theories state that, under typical conditions, the collapse of extremely dense matter inevitably leads to a singularity. But how exactly the rules of quantum mechanics, which dictate the behaviour of tiny particles, apply at the ultrasmall scales of a singularity is unknown. The new theory proposes that a gravitational collapse does not necessarily have to end in a singularity. It uses mathematical equations to show a collapsing cloud of matter can become extremely dense and then 'bounce' and rebound outward into a new expanding phase. 'The bounce is not only possible, it's inevitable under the right conditions,' study author Enrique Gaztanaga writes in The Conversation. 'The cosmological implication of this new approach is a novel understanding of the origin of the universe that emerges from the collapse and subsequent bounce of a spherically symmetric matter distribution.' The theory combines the framework of general relativity, which applies to largescale cosmic objects like stars and galaxies, with the principles of quantum mechanics that dictate how tiny atoms and particles behave. Crucially, it explains an early state universe without implying the existence of mysterious forces. The new theory is also testable as it predicts that the universe is not flat but slightly curved like the surface of the Earth, researchers say. If future observations can confirm that the shape of the universe indeed has a small curvature, it could suggest that it all began from a bounce. 'The smoking gun for our bouncing scenario is the presence of a small spatial curvature,' researchers write. Scientists hope further development of the theory can shed more light on current cosmic mysteries like the origin of monster black holes, the nature of dark matter, and factors influencing the evolution of galaxies. 'The black hole universe also offers a new perspective on our place in the cosmos,' Dr Gaztanaga writes. 'In this framework, our entire observable universe lies inside the interior of a black hole formed in some larger 'parent' universe.'
