Amish Khalfan: The Underlying Beauty in the Physics of Particles

Imagine, as best you can, a physicist entering an apartment in which a delightful party is being held.

Prof. Amish Khalfan

The physicist notices some people on one side of the living room drinking fine wine and eating expensive cheese. Near the middle of the room, he hears a few others musing over the current bleak state of affairs of our world. And so here is this rather shy and detached theoretical physicist who finds himself in seemingly uncharted territory. He has worked alone for the better part of his life tackling the deep mysteries of nature and here he stands among laughter, noise and, well, fun. The physicist decides to take action. He walks by everyone and heads for the back wall. It is there that he has laid his eyes upon some books placed neatly on a worn shelf. Our physicist discovers that he is able to move through the crowd with relative ease and quickness. He meanders through and passes by rather unnoticed. It’s as if he is free, in the sense that he has no one with whom to interact and deter him from his destination.

In direct contrast, now imagine a young female drama student with long, flowing hair and a beaming smile. She enters the party area, and people are immediately drawn to her. Several people come to greet her and some try to win her attention with a clever joke. However, the student also wishes to head for the back of the room as she notices an aesthetic vase by where the shelf sits. As she makes her way there, she is continually bombarded with fellow partygoers. She can’t resist but to indulge them. Unlike the physicist, she reaches the back area not as quickly and efficiently as the physicist.

Both scenarios described above can be used to understand the ability with which fundamental particles of nature had been able to acquire mass, or simply, stuff. In the early part of the universe a soup of particles existed known as quarks and leptons. Such particles eventually came together to compose the atoms from which objects of everyday experience are made. Quarks are found to reside in the protons and neutrons that make up the nuclei of atoms. Leptons, such as electrons, swarm about the nuclei. Atoms, in a way, are tiny solar systems. In the 1960s, a true physicist by the name of Peter Higgs suspected that quarks and leptons didn’t always have mass. He theorized that such particles are in the current state that they are in because they have obtained mass from somewhere. Just like the drama student, who was slowed down by the crowd in the room, the quarks and leptons had been slowed down by their interaction with an all-pervasive field of energy, which would come to be known as the Higgs field. Coupling with the Higgs field is what is in fact responsible for the masses of the quarks and leptons that we measure today.

We also have particles of light, known as photons. Photons are massless. Such particles had not been able to interact strongly, in fact at all, with the Higgs field since they had been zipping along at an alarmingly high speed, which is something on the order of hundreds of millions of miles an hour. The photon can be likened to our physicist at the party who had walked through the party area rather quickly all the while having little to no interaction with those around him.

The fundamental unit, or quantum, making up the Higgs field is called the Higgs boson. Bosons have specific properties in terms of the way they condense at low temperatures. The Higgs bosons can be likened to the surrounding people from the party. It is believed that the bosons had clustered onto bare quarks and leptons allowing them to accumulate mass and subsequently slow down in their motions. The Higgs boson mechanism of mass acquisition also helps to explain why the symmetry between two fundamental forces of nature – electromagnetism and the weak nuclear force, broke apart long ago. Today, these forces are disparate with the electromagnetic force being responsible for everything from holding atoms in place to modern technology, and the weak nuclear force governing the spontaneous decay of unstable nuclei.

Recently, it was announced that there is extremely good evidence to support the existence of the Higgs boson after data extracted from the world’s largest particle accelerator, or atom smasher, had been extensively analyzed. The accelerator, known as the Large Hadron Collider, or LHC, is about 27 kilometers in circumference and lies underground straddling the border between France and Switzerland. The LHC smashes high-speed protons into one another. When high enough energies are reached during the collisions, exotic particles are created. The Higgs boson is believed to have been created from such collisions, but it decayed almost immediately after. Its actual existence had been inferred by analyzing the decay products it released.

The leading theoretical framework of physics known as the Standard Model seems to be more complete with the very likely discovery of the Higgs boson. We are becoming ever so close to having a full description of matter and energy and their distribution in our vast universe. It might be worthy to ask, however, what gives the Higgs its mass? Also, are there other properties such as electric charge that can be obtained by interaction with similar fields? Physics is a never-ending quest for truth and understanding, and it is now more exciting than ever to embark on this wondrous journey.

The author, Amish Khalfan, is an instructional assistant professor of physics at Yeshiva College. He has taught courses in general physics, quantum mechanics, electromagnetic theory and differential equations. Professor Khalfan’s research interests include mathematical physics, investigating quantum systems, and applications of quantum field theory.