New data have set the particle physics community abuzz.
- The first question ever asked in Western philosophy, "What's the world made of?" continues to inspire high energy physicists.
- New experimental results probing the magnetic properties of the muon, a heavier cousin of the electron, seem to indicate that new particles of nature may exist, potentially shedding light on the mystery of dark matter.
- The results are a celebration of the human spirit and our insatiable curiosity to understand the world and our place in it.
If brute force doesn't work, then look into the peculiarities of nothingness. This may sound like a Zen koan, but it's actually the strategy that particle physicists are using to find physics beyond the Standard Model, the current registry of all known particles and their interactions. Instead of the usual colliding experiments that smash particles against one another, exciting new results indicate that new vistas into exotic kinds of matter may be glimpsed by carefully measuring the properties of the quantum vacuum. There's a lot to unpack here, so let's go piecemeal.
It is fitting that the first question asked in Western philosophy concerned the material composition of the world. Writing around 350 BCE, Aristotle credited Thales of Miletus (circa 600 BCE) with the honor of being the first Western philosopher when he asked the question, "What is the world made of?" What modern high energy physicists do, albeit with very different methodology and equipment, is to follow along the same philosophical tradition of trying to answer this question, assuming that there are indivisible bricks of matter called elementary particles.
Deficits in the Standard Model
Jumping thousands of years of spectacular discoveries, we now have a very neat understanding of the material composition of the world at the subatomic level: a total of 12 particles and the Higgs boson. The 12 particles of matter are divided into two groups, six leptons and six quarks. The six quarks comprise all particles that interact via the strong nuclear force, like protons and neutrons. The leptons include the familiar electron and its two heavier cousins, the muon and the tau. The muon is the star of the new experiments.
For all its glory, the Standard Model described above is incomplete. The goal of fundamental physics is to answer the most questions with the least number of assumptions. As it stands, the values of the masses of all particles are parameters that we measure in the laboratory, related to how strongly they interact with the Higgs. We don't know why some interact much stronger than others (and, as a consequence, have larger masses), why there is a prevalence of matter over antimatter, or why the universe seems to be dominated by dark matter — a kind of matter we know nothing about, apart from the fact that it's not part of the recipe included in the Standard Model. We know dark matter has mass since its gravitational effects are felt in familiar matter, the matter that makes up galaxies and stars. But we don't know what it is.
Whatever happens, new science will be learned.
Physicists had hoped that the powerful Large Hadron Collider in Switzerland would shed light on the nature of dark matter, but nothing has come up there or in many direct searches, where detectors were mounted to collect dark matter that presumably would rain down from the skies and hit particles of ordinary matter.
Could muons fill in the gaps?
Enter the muons. The hope that these particles can help solve the shortcomings of the Standard Model has two parts to it. The first is that every particle, like a muon, that has an electric charge can be pictured simplistically as a spinning sphere. Spinning spheres and disks of charge create a magnetic field perpendicular to the direction of the spin. Picture the muon as a tiny spinning top. If it's rotating counterclockwise, its magnetic field would point vertically up. (Grab a glass of water with your right hand and turn it counterclockwise. Your thumb will be pointing up, the direction of the magnetic field.) The spinning muons will be placed into a doughnut-shaped tunnel and forced to go around and around. The tunnel will have its own magnetic field that will interact with the tiny magnetic field of the muons. As the muons circle the doughnut, they will wobble about, just like spinning-tops wobble on the ground due to their interaction with Earth's gravity. The amount of wobbling depends on the magnetic properties of the muon which, in turn, depend on what's going on with the muon in space.
Credit: Fabrice Coffrini / Getty Images
This is where the second idea comes in, the quantum vacuum. In physics, there is no empty space. The so-called vacuum is actually a bubbling soup of particles that appear and disappear in fractions of a second. Everything fluctuates, as encapsulated in Heisenberg's Uncertainty Principle. Energy fluctuates too, what we call zero-point energy. Since energy and mass are interconvertible (E=mc2, remember?), these tiny fluctuations of energy can be momentarily converted into particles that pop out and back into the busy nothingness of the quantum vacuum. Every particle of matter is cloaked with these particles emerging from vacuum fluctuations. Thus, a muon is not only a muon, but a muon dressed with these extra fleeting bits of stuff. That being the case, these extra particles affect a muon's magnetic field, and thus, its wobbling properties.
About 20 years ago, physicists at the Brookhaven National Laboratory detected anomalies in the muon's magnetic properties, larger than what theory predicted. This would mean that the quantum vacuum produces particles not accounted for by the Standard Model: new physics! Fast forward to 2017, and the experiment, at four times higher sensitivity, was repeated at the Fermi National Laboratory, where yours truly was a postdoctoral fellow a while back. The first results of the Muon g-2 experiment were unveiled on 7-April-2021 and not only confirmed the existence of a magnetic moment anomaly but greatly amplified it.
To most people, the official results, published recently, don't seem so exciting: a "tension between theory and experiment of 4.2 standard deviations." The gold standard for a new discovery in particle physics is a 5-sigma variation, or one part in 3.5 million. (That is, running the experiment 3.5 million times and only observing the anomaly once.) However, that's enough for plenty of excitement in the particle physics community, given the remarkable precision of the experimental measurements.
A time for excitement?
Now, results must be reanalyzed very carefully to make sure that (1) there are no hidden experimental errors; and (2) the theoretical calculations are not off. There will be a frenzy of calculations and papers in the coming months, all trying to make sense of the results, both on the experimental and theoretical fronts. And this is exactly how it should be. Science is a community-based effort, and the work of many compete with and complete each other.
Whatever happens, new science will be learned, even if less exciting than new particles. Or maybe, new particles have been there all along, blipping in and out of existence from the quantum vacuum, waiting to be pulled out of this busy nothingness by our tenacious efforts to find out what the world is made of.
Lederman helped promote the importance of particle physics to the general public and his research laid the groundwork for the Standard Model.
- Lederman won the 1988 Nobel Prize in Physics for discovering a second type of neutrino.
- He coined the nickname 'God particle' for the Higgs boson in his 1993 bestseller The God Particle: If the Universe Is the Answer, What Is the Question?
- In 2015, Lederman and his family sold his Nobel Prize to pay for medical bills resulting from dementia.
Leon Lederman, a Nobel laureate and particle physicist celebrated for his sense of humor and ability to explain physics to the general public, has died at the age of 96.
During his long and decorated career, Lederman directed the Fermi National Accelerator Laboratory, coined 'the God particle' as a popular term for the Higgs boson, and conducted groundbreaking research that helped lay the foundations for the Standard Model of particle physics, which scientists use to explain nearly every force in the universe besides gravity.
In 1988 Lederman and two of his colleagues won the Nobel Prize in Physics for discovering a second type of neutrino, the muon. (Scientists later discovered a third called the tau.) The Nobel Foundation wrote:
"In decays of certain elementary particles, neutrinos are produced; particles that occasionally interact with matter to produce electrons. Leon Lederman, Melvin Schwartz, and Jack Steinberger managed to create a beam of neutrinos using a high-energy accelerator. In 1962, they discovered that, in some cases, instead of producing an electron, a muon (200 times heavier than an electron) was produced, proving the existence of a new type of neutrino, the muon neutrino. These particles, collectively called "leptons", could then be systematically classified in families."
In addition to discovering and experimenting with subatomic particles, Lederman also promoted the importance of particle physics to the general public, most prominently in his 1993 bestselling book The God Particle: If the Universe Is the Answer, What Is the Question?
He described his choice to nickname the Higgs boson like this:
"This boson is so central to the state of physics today, so crucial to our final understanding of the structure of matter, yet so elusive, that I have given it a nickname: the God Particle. Why God Particle? Two reasons. One, the publisher wouldn't let us call it the Goddamn Particle, though that might be a more appropriate title, given its villainous nature and the expense it is causing. And two, there is a connection, of sorts, to another book, a much older one... "
To say the nickname was disliked by physicists, including Peter Higgs himself, would be an understatement. In a 2009 article for The Guardian, science journalist Ian Sample asks a Manchester University physicist what he thinks of the name:
"He paused. He sighed. And then he said: "I really, really don't like it. It sends out all the wrong messages. It overstates the case. It makes us look arrogant. It's rubbish." He then added: "If you walked down the corridor here, poked your head into people's offices, and asked that question, you would likely be struck by flying books."
Although he was an atheist, Lederman didn't propose that physics could provide an all-encompassing explanation for our universe.
"There's always a place at the edge of our knowledge, where what's beyond is unimaginable, and that edge, of course, moves," Lederman told The New York Times in 1998, adding that we might know the laws of physics but we don't know where they came from, leaving us "stuck."
"I usually say, 'Go across the street to the theology school, and ask those guys, because I don't know.'"
In 2015, Lederman's Nobel Prize gold medal was auctioned off for $765,002 to pay for his medical bills that resulted from dementia.
"I'm shocked it sold at all," Lederman's wife, Ellen, told The Associated Press. "It's really hard. I wish it could be different. But he's happy. He likes where he lives with cats and dogs and horses. He doesn't have any problems with anxiety, and that makes me glad that he's so content."
Lederman once described the mindset in which he often found himself doing his best work. "The best discoveries always seem to be made in the small hours of the morning, when most people are asleep, where there are no disturbances and the mind becomes most contemplative," he told science writer Malcolm W. Browne in Discover magazine in 1981.
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:
Researchers believe it may help uncover the secret to how the pyramid was built.
The Great Pyramid itself, built by the Pharaoh Khufu (or Cheops) is one of the oldest monuments standing. It’s 456 ft. high (139 m) and thought to be around 4,500 years old. This is the largest of all the ancient pyramids and one of the most impressive structures ever built by human hands. It’s also puzzled modern scholars in a number of ways.
How exactly it was built has been the biggest question and it’s been mulled over for centuries. Despite our advanced technology, experts still don’t agree on how it was done. Fortunately, a discovery about the Great Pyramid offers a new avenue for us to explore, in order to gain insight into how it was built. Researchers used a unique method to visualize the internal architecture of Khufu's Great Pyramid, one of Earth’s most iconic structures.
Remember the pyramid isn’t only a monument but King Khufu’s tomb. This greatest remnant of Egypt’s Old Kingdom contains several spaces with connecting corridors including a King’s Chamber, Queen’s Chamber, and a Grand Gallery—essentially an enormous passageway 153 ft. long (46.6 m) and 26 ft. (7.9 m) high. It terminates in the pharaoh’s chamber.
These scientists found a space sitting atop the Grand Gallery that’s at least 98 ft. (30 m) long and perhaps longer. This is the first time since the 19th century that a chamber inside of the Great Pyramid has been discovered. Researchers still aren’t sure if it’s horizontal or vertical, and if it’s one large chamber or two, or even a series of chambers.
The internal structure of the Great Pyramid. By Jeff Dahl, via Wikimedia Commons
Some dream of priceless treasures being unearth. UK Egyptologist Aidan Dodson told Scientific American that there’s no chance of a new burial chamber having been discovered. What’s so compelling though is that no one knows what's in there.
Engineers, physicists, and archeologists contributed to this research as part of the international collaboration known as the ScanPyramids project. That’s in turn part of the Heritage Innovation Preservation Institute (HIP). HIP is a nonprofit located in France, dedicated to preserving humanity’s cultural heritage through the use of modern technology. The scientists teamed up with colleagues at Nagoya University in Japan to probe the Great Pyramid in an entirely new way, using high-energy particle physics.
Cosmic rays constantly bombard the Earth, but the upper atmosphere takes the brunt of this onslaught. What’s left over are harmless particles known as muons. These make it to the surface in vast multitudes. Blast these subatomic particles through an object with a sensor on the other side and you’ll get a glimpse of the object’s internal architecture. The more muons put out, the better your visual. So that’s what researchers essentially did to the pyramid.
This same technology is often used for understanding the internal network of tunnels which make up a volcano, and it was also used to determine the situation with the Fukushima Power Plant’s damaged reactor when it melted down. A similar attempt was made with muon detection in a smaller pyramid in the 1970s.
Nothing was found at that time, but the method has improved significantly since then. Sensitive muon detectors have been fashioned for work in particle accelerators, and these have helped bring this discovery to fruition.
The mysteries of the Great Pyramid may soon be solved. Credit: Getty Images.
Kunihiro Morishima of Nagoya University was the lead researcher on this study. He and colleagues launched this project by placing muon detectors in the Queen’s Chamber in December 2015. Muons can travel through rock, depending on the type and density. Knowing this, scientists were surprised when many more muons were received by their sensors than expected, meaning they were passing through a large void.
Dr. Morishima soon called in help from Japan’s High Energy Accelerator Research Organization and France’s Alternative Energies and Atomic Energy Commission. The teams of scientists used different kinds of muon sensors and detector films to trace back these subatomic particles and develop a more sophisticated picture of the anomaly inside. This second leg started in August 2016 and wrapped up in July of this year. Readings were taken at multiple locations in and around the pyramid.
There are several theories on what the chamber might be for. It could be a “relieving chamber” to take weight off the Grand Gallery. It could be part of a sophisticated counterweight system that helped raise the granite which comprises the King’s Chamber. Or it could be part of a ramp that helped masons construct the pharaoh’s final resting place. More research will hopefully yield a greater understanding of this millennia-old enigma.
To see ScanPyramids official report, click here: