In the first trillionth of a second after the Big Bang, the universe was a seething cauldron where the electromagnetic and weak nuclear forces were one. Now, scientists at CERN have managed to recreate these primordial conditions.1
By doing so, they’ve effectively turned back the cosmic clock, offering an unprecedented glimpse into the very origins of our cosmos and the fundamental forces that govern it.
But how did they achieve this remarkable feat, and what discoveries await us in this uncharted realm of physics?
Turning Back the Clock
Using the Large Hadron Collider (LHC), the world’s most powerful particle accelerator, physicists have been able to smash protons together at energies approaching those found in the early universe. By doing so, they’ve effectively turned back the clock, allowing the electroweak force to briefly reassert itself before splitting into the distinct forces we know today.
The LHC accelerates protons to nearly the speed of light in opposite directions around a 16.8 mile ring. When these protons collide, they create conditions similar to those that existed just after the Big Bang, with temperatures reaching over 10^15 Kelvin (about 1.8 x 10^12 °F).
At these extreme energies, the electromagnetic and weak forces merge into the electroweak force.(ref)
Precision Measurements & the Higgs Mechanism
At the heart of this groundbreaking research lies the electroweak mixing angle, a crucial parameter that determines the relative strength of the electromagnetic and weak forces.
By making incredibly precise measurements of this angle, scientists have been able to shed new light on the intricate dance between these forces and the role played by the Higgs mechanism in giving particles their mass.
Higgs Mechanism
The Higgs mechanism, proposed in the 1960s, explains how the W and Z bosons that mediate the weak force acquire mass while the photon of the electromagnetic force remains massless. This mechanism involves interactions with the Higgs field, which permeates all of space.
Excitations of this field manifest as the Higgs boson, discovered at the LHC in 2012.(ref) The masses of the W and Z bosons, as well as other particles, arise from their interactions with the Higgs field.
Recent precision measurements of the electroweak mixing angle by the CMS collaboration at the LHC have reached an unprecedented level of accuracy. These measurements probe the intricacies of the electroweak theory and the Higgs mechanism, allowing rigorous tests of the Standard Model of particle physics.
So far, the results align remarkably well with theoretical predictions.
The Quest for Unification
The electroweak interaction is just one piece of the puzzle when it comes to understanding the fundamental forces of nature. Physicists have long dreamed of a “theory of everything” that would unite all four forces – strong, weak, electromagnetic, and gravity – into a single, elegant framework. While we’re not there yet, studies like this one bring us one step closer to that ultimate goal.
Grand Unified Theories (GUTs) attempt to describe the strong, weak, and electromagnetic forces as different aspects of one force.(ref) They predict that at extremely high energies, like those present shortly after the Big Bang, these three forces merge into a single electronuclear force.
While energy scales required to directly probe grand unification are beyond the capabilities of current accelerators, physicists look for indirect hints, such as the possible decay of the proton predicted by some GUTs.
Incorporating gravity remains an even greater challenge. String theory and M-theory represent efforts to develop a quantum theory of gravity and unite it with the other forces. However, these theories are still highly speculative and face significant obstacles to experimental verification.
The Future of Particle Physics
As exciting as these results are, they’re just the beginning. Scientists are already looking ahead to the next generation of particle accelerators, such as the proposed electron-positron colliders known as “Higgs factories.” These machines promise to unlock even more secrets of the electroweak interaction and the early universe, paving the way for a new era of discovery in particle physics.
Potential future colliders include the International Linear Collider (ILC), the Compact Linear Collider (CLIC), the Future Circular Collider (FCC), and the Circular Electron Positron Collider (CEPC). These colliders would produce Higgs bosons and other particles in unprecedented numbers, enabling extremely precise measurements of their properties.
Such precision could reveal deviations from Standard Model predictions, hinting at new physics beyond our current theories.
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Nancy Maffia
Nancy received a bachelor’s in biology from Elmira College and a master’s degree in horticulture and communications from the University of Kentucky. Worked in plant taxonomy at the University of Florida and the L. H. Bailey Hortorium at Cornell University, and wrote and edited gardening books at Rodale Press in Emmaus, PA. Her interests are plant identification, gardening, hiking, and reading.
