A new study rocks prevailing theories on antimatter in the early Universe.
- Scientists from around the world teamed up to study the properties of neutrons.
- They were able to achieve extremely precise measurements of electric compasses in neutrons.
- The results challenge current theories of why antimatter and matter didn't destroy each other in the early Universe.
When expressed in physics terms, one of the most important human questions of "Why do I exist?" can be expressed as "Why is there more matter than antimatter?" In other words, during the Big Bang, a tremendous amount of antimatter was created, which could have cancelled out the matter. So why didn't it? In a newly published study, scientists came closer to understanding the answer by measuring properties of neutrons with unprecedented precision.
The team looked at whether a neutron, a fundamental particle of the Universe, can act as an "electric compass" by measuring its EDM (Electric Dipole Moment). This property results from the somewhat asymmetrical shape of a neutron, which is slightly positive at one end and slightly negative at the other, making it like a bar magnet, as explains the press release from the University of Sussex.
The team discovered that the measured EDM of the neutrons was much smaller than the theories predicted, pointing to the possibility that they need to be improved or replaced.
Big Bang and early Universe expansion.
Explanations related to matter left over after the Big Bang predict the existence of such "electric compasses" in neutrons, and understanding this phenomenon is essential to figuring out why matter didn't just disappear.
As explained by CERN, the Big Bang was supposed to create an equal amount of matter and antimatter, and yet obviously the things we see around us now are very much made of matter.
Where is the antimatter? Why is there such an asymmetry between matter and antimatter, whose particles are produced in pairs? If ever they were to come in contact, they would destroy each other, leaving only pure energy behind. And yet that's not what ultimately seems to have happened.
Apparatus for Measuring the Neutron's EDM.
Credit: University of Sussex
Professor Philip Harris of the University of Sussex, who led the EDM group, said that their results were a culmination of more than two decades of work by numerous scientists, while their particular experiment took measurements over two years.
"We've found that the "electric dipole moment" is smaller than previously believed," he pointed out. "This helps us to rule out theories about why there is matter left over - because the theories governing the two things are linked."
He also pointed out that their team "set a new international standard for the sensitivity of this experiment." The asymmetry they were able to pinpoint is extremely tiny but their experiment measured it "in such detail that if the asymmetry could be scaled up to the size of a football, then a football scaled up by the same amount would fill the visible Universe," he added.
To achieve this precision, the scientists upgraded an apparatus that has held the world's sensitivity record from 1999 till now. The measurements they achieved were so accurate that they'd compensate even for such factors as a truck driving by their institute, which would disturb the magnetic field enough to affect their experiment.
In total, the scientists measured over 50,000 bunches, each containing more than 10,000 ultracold neutrons, which move relatively slowly.
What can old stars teach us about the birth of our galaxy? ...
Dr. Clark Griffith, who lectures Physics at the University of Sussex, expounded on the multi-disciplinary components involved in the findings:
"This experiment brings together techniques from atomic and low energy nuclear physics, including laser-based optical magnetometry and quantum-spin manipulation," he shared.
These tools allowed the scientists to probe "questions relevant to high-energy particle physics and the fundamental nature of the symmetries underlying the universe," said Dr. van der Grinten.
The scientists hope their search will lead to a "new physics" that would expand upon the Standard Model. Previous developments in measuring EDMs, which stared in the 1950s, resulted in such technology as atomic clocks and MRI scanners.
The team included scientists from the UK's University of Sussex, the Science and Technology Facilities Council's (STFC) Rutherford Appleton Laboratory in the UK, the Paul Scherrer Institute (PSI) in Switzerland, with 18 organizations involved overall.
Their results were published in the February 28, 2020 issue of the journal Physical Review Letters.
What caused the Big Bang? Consider the beer bottle.
BASE particle physicists have discovered a very precise way to examine antimatter.
Thank your lucky stars you’re alive. It’s truly a miracle of nature. This has nothing to do with spirituality or religion and everything to do with science. Life itself may not be the miracle. Although we haven’t found it elsewhere yet, our galaxy alone is so replete with Earth-like planets that, mathematically speaking, one of them must hold life, even if it’s just the microbial variety. Intelligent life may be another matter.
What CERN scientists say as a result of their latest experiment is: the universe itself is a miracle, as it shouldn’t exist at all. This is of course taken in reference to the Big Bang theory. Though the prevailing one, it’s not the only theory to explain how all and everything came into being. Still, in this view, it all starts with the singularity.
According to the Big Bang, the universe began as a point the size of a grain of sand that was unimaginably hot, unfathomably dense, and packed tight with matter and energy. Then of course it exploded, sending its contents sailing out and eventually, forming the universe as we know it. There’s a few problems with this theory. For one, there’s the increasing rate of universal expansion, known as the Hubble Constant. According to the Big Bang, things should be slowing down, or even contracting. Dark energy is the conventional explanation, even though we can't prove it exists.
There’s another problem and here’s where the CERN scientists come in. The environment that produced the particles that make up the universe, as we know them now, should have created equal parts matter and antimatter. Yet, the latter is surprisingly rare. Not only that, a 50-50 split would’ve seen each particle uniting with its polar opposite, creating a burst of unimaginable energy and leaving nothing behind, save a vast howling void of a cosmos. And yet, here we are.
Particle physicists in the BASE collaboration at CERN have been investigating the matter-antimatter imbalance. Credit: Getty Images.
One theory is that matter and antimatter must in some way be radically different. But the latest CERN experiment does not find this is the case. According to the Standard Model of physics, a manual for every known particle in the universe and how it operates, each type of atom has its polar opposite, its antiparticle, with the same mass, but with an opposite electrical charge.
In this study, CERN scientists tried to discern what fundamental difference such particles should have, to validate the existence of the cosmos. They came up empty. Physicists in the BASE collaboration at CERN, studied the magnetic properties of protons and antiprotons with uncanny precision. Some good news: the findings did support the Standard Model, as the particles behaved just as it predicts.
The matter-antimatter imbalance, as it’s called, is a popular topic among particle physicists these days, with many teams around the world looking into it. CERN researcher Christian Smorra was on the team who conducted the most recent experiment. He told Science Alert, "All of our observations find a complete symmetry between matter and antimatter, which is why the Universe should not actually exist."
He added, "An asymmetry must exist here somewhere but we simply do not understand where the difference is. What is the source of the symmetry break?" He and his colleagues' findings were published in the journal Nature.
When matter and antimatter particles collide, a burst of pure energy is the result. If these were perfectly balanced in the early days of the universe, how could the cosmos exist at all? Credit: Getty Images.
Protons and antiprotons were the last holdout when it came to particles which could explain the matter-antimatter imbalance. Scientists from Mainz University in Germany devised a manner to assess the magnetism of a particle of antimatter that is 350 times more precise than the previously method. The readout was incredible, to nine places!
-2.7928473441 nuclear magnetons. A proton has the same level of magnetism, only it's positive. Although the study failed to explain our universe’s extreme prejudice towards matter, it did give us a far better understanding of an antiproton’s magnetism.
Antimatter doesn’t last long. As such, it needs to be contained. Researchers used two Penning traps, which are devices that retain antimatter particles using an electrical and a magnetic field. Stefan Ulmer, spokesperson for the BASE collaboration at CERN, said in the press release:
“The measurement of antiprotons was extremely difficult, and we had been working on it for ten years. The final breakthrough came with the revolutionary idea of performing the measurement with two particles. This result is the culmination of many years of continuous research and development, and the successful completion of one of the most difficult measurements ever performed in a Penning trap instrument.”
New plans in the works may unveil the secrets of the matter-antimatter imbalance. Pictured here: The Lagoon Nebula in Sagittarius. Credit: Hewholooks, Wikimedia Commons.
Up until now, scientists have probed the differences between particles and their opposites by comparing their electrical charge, magnetism, and mass. Next, this team plans to investigate them in terms of gravity, to see if a discrepancy exists there. Another international collaboration based at CERN, called ALPHA, will be studying what asymmetry, if any, exists between hydrogen and antihydrogen atoms. The BASE team meanwhile, also plans on further examining antiparticles magnetically.
Another important development at CERN, a new linear accelerator introduced at the facility in May, will allow the Large Hadron Collider (LHC) to reach greater luminosity by 2021. CERN Director General, Fabiola Gianotti, said at its unveiling, “This high-luminosity phase will considerably increase the potential of the LHC experiments for discovering new physics and measuring the properties of the Higgs particle in more detail.” Perhaps discoveries made here will help unravel the secret behind the matter-antimatter imbalance.
To learn more about antimatter, click here:
Scientists work out methods for finding the difference between the magnetic moments of protons and antiprotons and see that they’re the same.
Why are we here, anyway? No, not in the what’s-the-meaning-of-it-all sense, but why haven’t matter and antimatter completely obliterated each other, the universe and us? In nature, two identical things that are 180° out of phase with each other — as matter and antimatter seem to be — cancel each other out. So, um, why are we here?
In audio, for example, two identical sound waves that are out of phase in this way produce silence:
So even if, say , you’re talking about identical recordings of something loud like a car horn, you get:
So we’ve got a problem with matter and antimatter not doing this, or rather, we should have a problem. Physics’ standard model says that when the universe came into being at the Big Bang, an equal amount of matter and antimatter was generated that should have — in our current understanding — wiped each other out, preventing the universe as we know it from forming.
Scientists have been thinking there must be something we haven’t come across yet that makes matter and antimatter not truly identical. A just-released study in the journal Nature reveals the frustrating outcome of a recent search for that difference at CERN. Christian Smorra, a physicist with their Baryon–Antibaryon Symmetry Experiment (BASE) collaboration, says, “An asymmetry must exist here somewhere but we simply do not understand where the difference is,” because, “All of our observations find a complete symmetry between matter and antimatter, which is why the universe should not actually exist.”
Previously, scientists have tried to find some difference other than polarity in matter and antimatter, measuring their mass and electric charge, and with a study last year of the properties of hydrogen and anti-hydrogen atoms: Nothing.
One aspect scientists haven’t been able to compare precisely before were the magnetic moments of the proton and antiproton — there’s been simply no way to do it. ( A magnetic moment is a measurement of an object's tendency to align with a magnetic field.) So ten years back, a team at BASE began trying to work out how they could.
BASE’s antiproton decelerator at CERN (STEFAN SELLNER, FUNDAMENTAL SYMMETRIES LABORATORY, RIKEN, JAPAN)
In 2014, BASE announced their first breakthrough: They could measure the magnetic moment of protons by trapping them in a magnetic field and inducing quantum jumps in the field’s spin using a separate magnetic field.
Tricky as that was, performing the same measurement in antiprotons was even thornier, since antiprotons are immediately destroyed when they come in contact with regular matter, such as one of the scientists’ containers.
The team figured out how to increase the the lifespan of antiprotons by holding them in an innovative, purpose-built iridium-sealed copper cylinder.
The chamber is said to look not unlike a Pringle’s can. (SELLNER, ET AL)
CERN describes the operation of the chamber, the most effective antimatter container ever made:
The reservoir trap is inside a cylinder with a volume of 1.2 litres. The particles are trapped by two overlying magnetic and electric fields, which keep the particles in a small volume in the centre of the trap. On one side of the trap there is a metal window, thin enough to allow the antiprotons to pass through but strong enough to ensure complete insulation from the outside. All the other sides of the trap are made from solid copper. The cylinder is then cooled to about 6 K (-267 °C) with liquid helium, so that an almost perfect vacuum is created.
A stream of antiprotons was fired into the frigid container on November 12, 2015, and the team was able to hold them there for an impressive 405 days.
During that time, they were able to run the magnetic moment measurement procedure they used for protons.
The new research documents the results of their efforts: the magnetic moment of an antiproton, out to nine places, is −2.7928473441 μN (μN is the symbol for micronewton force). And guess what? That’s identical to the magnetic moment of a proton. Could the difference lie somewhere beyond nine mathematical places?
Maybe, but, as Stefan Ulmer, leader of the BASE team avers, “This result is the culmination of many years of continuous research and development, and the successful completion of one of the most difficult measurements ever performed in a Penning trap instrument.”
So, for now, the puzzle continues, and scientists will keep sleuthing in hopes of solving this fundamental mystery : Why are we here?
CERN researchers make a major step in understanding antimatter by trapping antihydrogen atoms and controlling them with lasers.
Antimatter is a concept that oozes sci-fi, evocative of amazing engines, time travel and most likely destruction of the whole universe. Or maybe it’s a parallel-worlds-are-everywhere-around-us type of thing. In any case, this idea comes to us from the law of physics that predicts that there should be an antimatter particle for every particle of regular matter. But if the two shall ever meet, there’d be a release of energy, annihilating both.
This goes to the heart of the mystery of how our universe was created. If equal amounts of matter and antimatter were produced by the Big Bang, how did everything not just explode or just vanish? Why are we even here?
To study this, scientists have been trying to understand antimatter, looking for decades to compare its properties to matter. And a new report from CERN in Switzerland confirms that for the first time ever researchers were able to control an antimatter particle of the hydrogen atom, manipulating it long enough with lasers to allow for measurement and comparison with the regular matter hydrogen atom.
In particular, scientists from the ALPHA experiment at the CERN laboratory were able to hit the antihydrogen atoms with a laser to observe the light they gave off as positrons in the atoms returned to lower energy levels.
“Using a laser to observe a transition in antihydrogen and comparing it to hydrogen to see if they obey the same laws of physics has always been a key goal of antimatter research,” said Professor Jeffrey Hangst, spokesperson of the ALPHA collaboration.
Professor Jeffery Hangst. Credit: CERN
This result is the culmination of 20 years of work for CERN’s antimatter team. Unable to find antihydrogen atoms in nature, scientists worked on creating them in the lab. The challenge has been to trap enough of them for long enough to be able to study them. Previous efforts averaged 1.2 antihydrogen atoms trapped every 15 minutes. The new method created about 25,000 antihydrogen atoms every 15 minutes and trapped about 14 of them.
If you think your job is hard, try working with antimatter.
"What you hear about in science fiction — that antimatter gets annihilated by normal matter — is 100 percent true," Hangst told NPR, "and is the greatest challenge in my everyday life."
In other words, his test subjects would constantly disappear.
Images show anti-hydrogen atoms annihilating as they come into contact with the ordinary matter walls of the ALPHA experiment. Credit: CERN
Interestingly, the researchers concluded that under the same test conditions, the antihydrogen atoms gave off the exact same light spectrum as regular hydrogen atoms.
"It’s long been thought that antimatter is an exact reflection of matter, and we are gathering evidence to show that is indeed true," Tim Tharp from ALPHA said to Gizmodo.
To go back to the question of why the universe didn’t just collapse in on itself, with matter and antimatter cancelling each other out -
"Something happened, some small asymmetry that led some of the matter to survive, and we simply have no good idea that explains that right now," explained Jeffrey Hangst to NPR.
Further study of antimatter might yield the answer, especially as the work by Hangst and the team at ALPHA points the way towards a whole new field of antihydrogen spectroscopy.
CERN's Alpha lab (Image: Maximilien Brice/CERN)
But what about making antimatter in a lab environment - could that blow us up eventually?
“The amount of antimatter involved in this experiment and created by the history of mankind is such a small amount that it poses no threat to anyone,” Tim Tharp reassured Gizmodo.
We’ll have to take his word for it. In the meantime, let's dream about this antimatter rocket -
An antimatter propulsion system. 199. Credit: NASA.