Higgs Boson : Science Story of the Year.

Geological studies estimate earth to be around 4.5 billion years old. Anthropological studies reveal that the anatomical evolution of human beings was completed some 50,000 years ago. Since then, man, in his quest to know about the universe in which he is placed, has been working towards and praying for: “What in me is dark, / illumine, what is low, raise and support”.

Right from Galileo Galilei to Issac Newton, Albert Einstein, Max Planck, Werner Heisenberg to today’s Steven Weinberg, A Salam, S Glashow, Gell-Mann, Neeman, Stephen Hawking, it is the quest to ‘comprehend the apparently incomprehensible’—the underlying reality behind the universe—that has eluded and is eluding the greatest scientists of the day.

Intriguingly, as early as in the 19th century, the end of this enigma appeared to have come closer to man when Albert Michelson said: “Future discoveries (in Physics) must be looked for in the sixth place of decimals.” But that is not what it turned out to be: Einstein came out theorizing that space and time are inextricably interrelated and that mass and energy are two sides of the same coin. Then we had Max Planck coming out with a theory that rocked the world of Physics: light and other forms of energy exist as discrete particles, ‘quanta’. Disturbed by what Werner Heisenberg from Copenhagen, Paul Dirac from Cambridge, and Erwin Schrödinger from Zurich said under their quantum mechanics, Einstein expressed his anguish in his famous dictum: “God does not play dice.” 

Thus emerged the intellectual battle in explaining ‘quantum’ between the group of physicists led by Einstein on one side and the other led by an equally brilliant Niels Bohr. Over the years, experimental physicists—John F Clauser, Staurt Freedman, Alain Aspect, Jean Dalibard, Gerard Roge—have however tended to tilt towards Bohr’s proposition. Nevertheless, there are many physicists who continue to believe that particles are real even at the sub-atomic level and that the theory of quantum mechanics is incomplete.

Later research by particle physicists led to the realization that while the electron is a truly fundamental particle, neutrons and protons are made up of smaller particles known as quarks, which are, of course, considered as truly elementary. This lead to the formulation of the ‘Standard Model’—a model that attempts to explain the fundamental building blocks of the universe and the forces through which these blocks interact.

According to the Standard model, there are twelve basic building blocks: six of these are quarks, named up, down, charm, strange, bottom, and top; the remaining six are leptons that consists of electron and its two heavier siblings—the muon and the tauon, plus three neutrinos. There are also six 6 antiquarks and six antileptons. All the known particles are thus the composites of quarks and leptons.

There are four fundamental forces in the universe: gravitational, electromagnetism, weak and strong nuclear forces. However, Standard model explains only the strong, weak, and electromagnetic fundamental interactions using mediating gauge bosons. The gauge bosons are: eight gluons that carry strong force; W–, W+, and Z bosons that transmit weak force, and the photons that mediate electromagnetic forces.   

Finally, the Standard model predicts the existence of a type of boson (for, it has a certain value of a quantum-mechanical property known as spin), named Higgs boson (named after a British physicist, one of its leading developers), but not a gauge boson. According to Higgs theory, particles live in a field, called Higgs field, with which they interact. And these interactions result in attraction of Higgs bosons to the particles whereby they gain mass. Thus, Higgs boson has two functions: one, to give mass to particles, and two, to enable the Standard model to function as defined.

Identification of Higgs boson, the hypothesized elementary particle, is thus highly critical for the very validation of the Standard model. In other words, unless Higgs is identified, all that what physicists claim to know today about the universe would be wrong. It is to identify Higgs presence, physicists working at CERN in Geneva crashed bunches of protons coming in opposite directions at enormously high energies by accelerating them to move at near the speed of light in the CERN’s Large Hadron Collider (LHC). When protons collide, their energy is converted into other particles. Massive magnetic systems in the form of ATLAS—A Toroidal LHC Appratus— and CMS—Compact Muon Solenoid is specially looking for the Higgs boson— that are placed on opposite sides of the LHC’s loop, are supposed to facilitate bending of the paths of the charged particles so that they can be measured. It is with the help of these instruments that the patterns of observable particles that Higgs is theoretically supposed to break into are identified. 

Based on the findings of the study carried out, physicists working at CERN announced on 4^th July, that they had found Higgs boson. It is indeed a crowning achievement for the physicists, though it is not the end of the story, for it asks new questions: Does the particle identified by them match with the prescribed properties of Higgs? If not, what it means to the Standard model? How about the matter-antimatter asymmetry?    

And of course, that is what Science is all about—a constant search for truth!      

          

Images Courtesy: guardian.co.uk, csmonitor.com