Report on future of particle physics outlines exciting scientific priorities
CHICAGO (CBS) -- A powerful new particle accelerator that could be set up at Fermilab, a telescope to observe the oldest light in the universe, and research to learn more about mysteries such as dark matter were all among the priorities identified in a new report on the future of particle physics issued Thursday.
The report by the 2023 Particle Physics Project Prioritization Panel – or P5 – lists recommendations for federal funding agencies for what should be constructed to advance particle physics research over the next 10 years. This is the first new P5 report since 2014, and the panel behind it is hoping its suggestions will help shed light on some of the most puzzling mysteries of science and the universe.
Abigail Vieregg – a professor at the Department of Physics, the Enrico Fermi Institute, the Kavli Institute for Cosmological Physics, and the College at the University of Chicago – was a member of the 2023 P5. She talked with CBS 2 Thursday afternoon about some of the most ambitious and exciting science that P5 has identified as its priorities in the report.
A powerful new collider at Fermilab
Among the priorities identified by P5 is a muon collider – which would be even more powerful than the Large Hadron Collider at CERN in Geneva, Switzerland. The goal, Vieregg explained, is to "get to even higher energies of particles… accelerate them even faster – and make even more powerful collisions so we can learn about smaller and smaller scales."
The P5 report said the muon collider the committee has in mind would be about exactly the size of the campus of the Fermi National Accelerator Laboratory – or Fermilab – just outside west suburban Batavia. From 1983 until 2011, Fermilab hosted the Tevatron – which was the premier particle accelerator in the world when it was built, but which was considered outdated technology by the time it closed.
Currently, the distinction of the most powerful particle accelerator in the world belongs to CERN's Large Hadron Collider, or LHC. The LHC accelerates protons – which CERN said reach an energy of 6.5 million million electronvolts, or 6.5 tera-electronvolts. In the proposed muon accelerator, the particles would reach an energy of 10 tera-electronvolts, according to the P5 report.
Rather than protons, the proposed new accelerator would accelerate muons – subatomic particles that have a negative charge similar to electrons, but that each have 200 times as much mass as an electron. They would be even better for powerful collisions needed to advance the understanding of particle physics.
The report noted some challenges – including the need to capture and cool the muons before they decay. Muons have a lifetime of only 2.2 millionths of a second.
While the P5 panel said in its report that it did not know if a muon collider was "ultimately feasible," it would be "an unparalleled global facility on U.S. soil" if successful.
"This is our Muon Shot," the P5 committee wrote.
A 'Higgs factory'
Another priority for P5 involves the Higgs boson – popularly known as the "God particle." As explained years ago by The Straight Dope, the Standard Model of quantum physics succeeded in explaining the relationships between electromagnetism, the strong nuclear force that holds atomic nuclei together, and the weak nuclear force that relates to radioactivity. But the model did not take into account the force of gravity, and fails to explain why subatomic particles such as electrons and quarks have mass.
Scientists long believed subatomic particles gained mass by interacting with the "Higgs field," a "sticky" quantum field that fills all of space. The hypothesis was that the interaction involves, in essence, Higgs bosons sticking to the subatomic particles and thus gaining mass.
The Higgs boson was first predicted in 1964 – but it took until 2012 for scientists finally to observe and go on to confirm its existence. Now, Vieregg said, particle physicists hope to delve deeper into research on the Higgs boson by constructing a "Higgs factory."
"So what that would be is a particle collider that would make lots and lots of Higgs particles so we can really study the role that the Higgs plays in particle physics – and learn more about the mysteries of the Higgs boson," Vieregg said. "Discovering a particle is one thing, but then, figuring out more precisely how it works and how it fits into the rest of fundamental physics is what we'd like to do with a Higgs factory."
The Higgs factory would be constructed either at CERN in Switzerland, or in Japan.
Researching the mysteries of dark matter
The study of abundant, yet mysterious dark matter is also a major priority of P5.
"So it turns out that when you look at the way that the universe has evolved over time, and the way that galaxies work, we think that there's about five times as much dark matter as there is regular matter in the universe – which is kind of an astounding statement, actually," said Vieregg. "So regular matter is the things that you and I are made up of; that make up atoms and molecules. But it turns out that there is a lot more matter than that in the universe. They call it dark matter because it doesn't interact with light the way that regular matter does."
This means that when looking at a telescope pointed in the sky, one will not see dark matter. But it's there – and there's lots of it.
"We can tell it's there because of its gravitational effect," said Vieregg. "It's pulling on regular matter in the universe and making it clump in different ways."
But what is dark matter? It's a mystery – scientists still don't know. One of the goals of particle physics outlined by P5 is to focus on research to change that.
"So one of the things we'd like to do is discover dark matter in the lab. So we'd like to be able to build experiments that can measure dark matter particles and tell us what they are. So that's one of the major recommendations from the report as well, is to build experiments that can measure dark matter particles," Vieregg said. "And there's many, many different ways to do this, because there's many ideas for what dark matter might be. So dark matter is such an important question in particle physics – simply because it's more abundant than regular matter in the universe, and we'd like to figure out what it is."
Unlocking the enigmas of neutrinos
Another priority for P5 involving Fermilab focuses on its experiments with neutrinos. Neutrinos are the most abundant particles with mass in the universe. Each neutrino, as described by the U.S. Department of Energy, is "tiny, neutral, and weighs so little that no one has been able to measure its mass."
But neutrinos do, in fact, have mass – and particle physicists want to find out why. And while neutrinos were first predicted in 1930 and observed in 1956, they have many other properties that also remain mysteries.
Some research to solve those mysteries is already going on at Fermilab, and Vieregg said one of the P5 committee's priorities is to continue with those efforts and the construction needed for them.
The flagship experiment going on right now at Fermilab is called the Deep Underground Neutrino Experiment, or DUNE.
"DUNE is a neutrino experiment where using the accelerators and Fermilab, they can make neutrinos – and then they shoot a neutrino beam to a mine in South Dakota, actually," Vieregg said. "And then they are planning to build a large detector in South Dakota to detect the neutrinos when they get to South Dakota."
Why are neutrinos being fired nearly 1,000 miles underground from Fermilab to the Sanford Underground Research Facility in Lead, South Dakota, on the former site of a gold mine? Vieregg explained that scientists are already discovering curious properties of neutrinos from the experiments.
"So neutrinos have this really weird property where they do something that we call oscillation – so they change from one type of neutrino to another as they travel through space – which is an odd property if you think about it – that you can start with one type of particle; one type of neutrino, and then it goes 1,000 miles, and then when you detect it on the other side, it's a different type of neutrino," Vieregg said. "And so we'd like to find out the details of why neutrinos oscillate. That's question is related to sort of, what are the fundamental properties of neutrinos? Why do they have mass? Sort of, what's the physics that governs neutrinos?"
Vieregg said particle physicists believe neutrinos "hold secrets to physics beyond the standard model of particle physics."
Telescopes to observe the universe's oldest light
Vieregg said her personal highlight among all the projects the P5 committee listed as priorities is the CMB-Stage 4 – a cosmic microwave background telescope. There would be telescopes set up at the South Pole and in Chile.
One might ask – what does the study of incredibly minute subatomic particles have to do with the study of the most massive structures of the universe? The answer is, quite a lot. It can help scientists "find out sort of how the universe evolved over time, and what is the physics that's driving the acceleration of the universe?" said Vieregg.
To research that subject requires building telescopes and making detailed observations of the sky.
"So one way you do that is by looking at the oldest light in the universe – called the cosmic microwave background – which is leftover radiation from the Big Bang. And people have been measuring the cosmic microwave background with more and more precision since it was first discovered in the 1960s," Vieregg said. "But now, this panel has recommended to take a pretty large step forward and build the next generation of cosmic microwave background telescopes – called CMB-Stage 4."
The goal of the CMB-4 is to learn more about the physics of "the very early universe – the first tiny fractions of a second after the Big Bang," Vieregg said.
"We can learn about what happened in the universe at that time by making those measurements," she said.
The report also identifies several other priorities, such as a commitment to sustainability and energy management, a commitment to ethical research, and efforts to recruit, train, and retain a talented workforce and to engage with the public.
