Quirks & Quarks·Analysis

Suggestions of a new force echo the ancient quest for fundamental elements

Bob McDonald's blog: The quest to understand the nature of matter and reality is ancient — and continuing

Bob McDonald's blog: The quest to understand the nature of matter and reality is ancient — and continuing

Muon g-2 particle storage ring at Fermilab in Illinois. (Cindy Arnold)

Results from a particle physics experiment at Fermilab outside Chicago suggest the possible existence of a new force in nature, which if true, could shake the foundations of physics.

This quest to understand the basic structure of the universe goes back centuries to when ancient cultures sought to identify the fundamental elements of nature.

Classical Greek philosophers proposed that four elements provided the foundation for everything else to stand on: earth, air, fire and water (later, Earth, Wind & Fire became a great dance band in the '70s.) There was also a word to describe their fundamental nature, "atomos." This means indivisible, or un-cuttable, so that they cannot be broken down into simpler parts. If you cut water into smaller drops it is still water, cut fire, you still have fire, therefore these elements seemed fundamental.  

Empedocles, a philosopher from 5th century BCE Greece is thought to have established earth, air, fire and water as fundamental elements. ( Thomas Stanley, The history of philosophy, 1655)

Since then, science has been cutting deeper into what were once thought to be fundamental elements, only to find smaller and smaller pieces and that they themselves break down.

The atom itself was thought to be fundamental because everything is made of them. Then we found electrons circling around the outside and the hard nut of the nucleus containing protons and neutrons.

The invention of particle accelerators capable of driving particles close to the speed of light then smashing them together to break them apart, revealed smaller quarks, leptons, bosons — whole families of sub-atomic particles. As accelerators grow bigger and more powerful, this quest for and exploration of fundamental particles continues to this day.

Standard Model

Describing the whole assembly is an elegant and highly accurate set of equations called the Standard Model. It predicts, with great precision, how the particles and forces associated with them will behave. 

But the Standard Model has limits. It doesn't integrate with gravity and doesn't say anything about dark matter or dark energy.

While it's very useful, we know it's not a complete theory of how the universe works. So researchers have been looking for problems or exceptions or weaknesses with it which could be a foot in the door to a new theory that can give us deeper insights. 

That's why this new experimental result is exciting. The Fermilab experiment found that a subatomic particle, called a muon, may not behave as the Standard Model predicts.

This August 2017 photo made available by Fermilab shows the Muon g-2 ring at the Fermi National Accelerator Laboratory outside of Chicago. (Reidar Hahn/Fermilab via The Associated Press)

The muon is sometimes called, "the fat electron," because it has the same electric charge as an electron, but is much heavier.

A huge ring-shaped magnet was used to make the muons wobble around like spinning tops. The surprise came when they spun faster than predicted. This could be an experimental error. An error in measurement or even a loose cable connection in the equipment has sunk promising results in the past. But if the result is right, it could mean there is an extra force acting on the muons we didn't know about, and not predicted by the Standard Model, which opens a whole new plethora of possibilities.

The big questions

Scientists want to understand all of the particles and forces to come up with one single theory to describe them all: the theory of everything. They also want to answer the most fundamental question of all: how did it all begin?

You've heard of the Big Bang. It's a great description of how a super-hot, super-dense stew of energy transformed into particles that became atoms, then molecules, stars, galaxies, planets and people. But it doesn't describe the earliest trillionths of a second when the universe was so dense it could have fit in the palm of your hand. 

Any suggestion of a new force or a new particle that we didn't know about could provide a way to get insight into this earliest period in cosmic history. 

Artist's impression of the Big Bang and expansion of the universe. Image is not to scale. (Christine Daniloff, MIT, ESA/Hubble and NASA)

Perhaps it will help explain the formation of not only the stuff we are made of, but things we still don't completely understand, such as dark matter and dark energy, which make up 95 per cent of the matter and energy in the universe.

Further experiments will be needed to verify the existence of this extra force with greater certainty. If proven correct, the Standard Model will have to be adjusted to fit with what nature is telling us. But that has been the case since the ancient Greeks pondered the same questions. New experiments bring new knowledge that hopefully leads closer to the ultimate truth. 

In other words, this is more than finding the fundamental elements of the universe, this is about understanding how we came into existence.

WATCH |  Fermilab describes their Muon g-2 experiment


Bob McDonald is the host of CBC Radio's award-winning weekly science program, Quirks & Quarks. He is also a science commentator for CBC News Network and CBC-TV's The National. He has received 12 honorary degrees and is an Officer of the Order of Canada.