Higgs Boson: Why is it a Big Deal?
If you've missed the news that shook the scientific community on July 4, 2012 by the long awaited discovery of the Higgs Boson, and the confirmation of the discovery in March 2013, then read on. In this article I'll try to explain what Higgs Boson is, who discovered it and how, and why it is such a big deal.
Questioning the Obvious
The branch of science known to most of us as Physics is also referred to as Natural Philosophy. There's a very good reason for that. Like philosophers, physicists also ask questions about the nature of reality. Sometimes they ask questions that are 'obvious' to most people. We've all heard the story of Sir Isaac Newton seeing an apple fall from a tree that caused him to ask why the apple fell down (and not in any other direction). This of course led to the discovery and formulation of gravity --- a theory that made today's satellite technology and telecommunication possible, among many other things.
Another good example of questioning the obvious is why does time flow from the past to the future and never in the other direction (arrow of time)? Said in another way, why do we remember the past and not the future? To most of us this is not only obvious, but to be honest, quite silly! But that didn't keep scientists from asking. The answer to questions like this led to the all important discovery of the principle of entropy and thermodynamics --- a principle that powers today's internal combustion engines, refrigerators, air-conditioners and many other appliances and machines that rely on heat transfer.
Let there be mass!
One last example --- where does mass come from, or what gives particles their masses?
Isn't it how nature meant it to be --- a "given" fact of reality that we just accept? The beauty of science is that we don't have to accept anything, and get to question everything until we are satisfied, unlike it is in certain other disciplines of human endeavor.
The Higgs Field
Peter Higgs, a professor of Theoretical Physics at the University of Edinburgh (UK), in the 1960s mathematically proposed the existence of a field, that later came to be known as the Higgs Field, that answers this very question --- how do elementary particles acquire mass. According to this theory, particles gain mass by interacting with the Higgs field that permeates all space.
Particles gain mass by interacting with the Higgs field that permeates all space.
Mass essentially is the resistance an object exerts when force is applied to it --- the more massive an object, the higher the resistance. Because elementary particles have different properties (electric charge, spin etc), their interactions with the Higgs Field give rise to different masses. A good analogy, that came to be known as the 'cocktail party analogy' explains the effect in layman's terms:
Force Fields, Particles and the Higgs Boson
All force fields have particles associated with them. For example, photon is associated with electromagnetic fields. Likewise, gravitational field's associated particle is called Graviton (yet to be experimentally detected). What exactly does it mean for a field to have an associated particle? Let's try to understand this through an analogy again. Let's say you are standing at a given distance from me. I throw a ball at you in such a way so that to catch it and throw it back to me you have to come closer to me. The ball can be thought of having created an attractive force between you and me. Similarly, if I throw the ball so that you have to move away from me to catch it, the ball has essentially created a repulsive force. In nature attractive and repulsive force fields act somewhat similar to this analogy. This is particularly true for the types of particles that are thought of as carriers of forces. This class of particles is also called Bosons (named after Bengali physicist Satyendra Nath Bose, whose pioneering work with Albert Einstein in the 1920s changed the way particle physics has been studied. The University of Dhaka in Bangladesh, where he worked, still has a chair position named after him).
You probably guessed it by now, the particle associated with the Higgs Field is called the Higgs Boson.
The Higgs Boson has been described as the most sought-after particle in modern physics. The popular media often refers to the Higgs Boson as the 'God Particle'. Nobel Prize-winning physicist Leon M. Lederman used to refer to the Higgs Boson as "the goddamn particle". But in 1993 when he published a book with co-author Dick Teresi, he shortened it, thinking it'd be more appropriate to call it just 'God Particle' (his publisher also objected to calling it the goddamn particle). His Book was titled The God Particle: If the Universe Is the Answer, What Is the Question? The physicist community, however, doesn't like the Higgs Boson being referred to as the god particle. “I detest the name ‘God particle’. I am not particularly religious, but I find the term an ‘in your face’ affront to those who [are],” wrote physicist Vivek Sharma, a leader of the Higgs search. “I do experimental physics, not God.” Peter Higgs himself is not fond of it either --- "I find it embarrassing because, though I'm not a believer myself, I think it is the kind of misuse of terminology which I think might offend some people."
50 Years and a 10 Billion Dollar Chase for the Particle
It has been the longest and the most expensive manhunt in the history of science. Scientists have been looking for the experimental proof for the existence of the Higgs Boson ever since it was proposed in the sixties, and also were able to convince governments to shell out 10 billion dollars to build the machine that would eventually detect the particle. We'll come back to the question of why it is such a big deal. But before that let's talk about the search for the particle.
Detecting the Higgs Boson
We're all familiar with Albert Einstein's famous equation E = mc2, which basically quantifies the relationship between mass and energy, indicating that one can be converted in to another. This equation is utilized in the detection of elementary particles.
It has been the longest and the most expensive manhunt in the history of science.
If you can smash protons with sufficient energy in to one another, some of the energy of the collision gets converted in to mass, which shows up as a shower of elementary particles (some almost instantaneously decay in to other familiar particles). The higher the energy of the collision, the heavier the particles the collision is likely to create (Higgs Boson is about 125 times heavier than a proton). By detecting and analyzing the traces of these particles in a particle-accelerator, physicists can say a lot about the properties of these particles. Many new and previously unknown elementary particles have been discovered this way.
As indicated above, some particles live only for billionths of a second once they are created, and then decay in to other familiar particles. How do you "catch" these fleeting gems? Once again, Einstein to the rescue. According to the theory of relativity, time slows down for an object that is moving at sufficiently close to the speed of light --- his equation also shows by exactly how much. So by accelerating particles to very high speeds, physicists can make them last long enough to be detected and measured. Sometimes scientists indirectly detect particles by observing and measuring the particles they decay in to.
From Peter Higgs' paper, physicists had some idea of what properties a Higgs Boson is supposed to possess and how long it is expected to live before it decays in to other lighter particles. So physicists and engineers at CERN (European Organization for Nuclear Research) built the particle accelerator known as the Large Hadron Collider (LHC). The LHC was built in collaboration with over 10,000 scientists and engineers from over 100 countries, as well as hundreds of universities and laboratories. It lies in a tunnel 17 miles (27 kilometers) in circumference, and 574 ft (175 meters) underground near Geneva, Switzerland. You can think of it as a 17 mile long ring of superconducting magnets with a number of accelerating structures to boost the energy of the particles along the way. Protons are hurled thousands of times along the circumference until they reach a speed 99.9999991% of the speed of light, before they are collided head-on. The energy of the collision gives rise to the telltale signature of the Higgs Boson on the detectors. However, the detection of the boson is a very rare event – it takes about one trillion (1012) proton-proton collisions for each observed event. You can view some truly spectacular images of the LHC here.
Superconducting Super Collider (SSC) was going to be the largest particle accelerator in the word.
The US was on its way to building the world's largest and the most energetic particle accelerator known as the Superconducting Super Collider (SSC) in Texas in the eighties and the nineties that would surpass the current record held by the CERN's Large Hadron Collider. The SSC's planned ring circumference of 54.1 mi (87.1 km) was going to be more than three times that of LHC. If the US Congress did not cancel the project in 1993, United States would almost certainly have a shot at being the first to discover the Higgs Boson, ahead of the Europeans.
The Discovery Announcement
Interestingly, the July 4, 2012 announcement of the discovery was not framed very assertively. CERN claimed to have discovered a "Higgs-like" particle. Fortunately, further analysis of the data collected led the scientists to finally confirm the discovery of the Higgs Boson in March of 2013. According to CERN website: In July 2012, the ATLAS and CMS collaborations announced that they had discovered a new particle with a mass around 125 GeV. At this early stage, the phrase “Higgs-like boson” was used to refer to a boson whose properties were still to be fully investigated. Thanks to the outstanding performance of the Large Hadron Collider, in the second half of 2012 it delivered four times as much data at 8 TeV as was used in the analyses that led to “the discovery”. Thus equipped, the experiments were able to present new results in March 2013, with enough evidence to name this new boson “a Higgs boson”.
Why is it a Big Deal?
Besides explaining the origin of mass, experimental discovery of the Higgs Boson has other profound scientific implications. We are now able to look in to the fabric of nature the way we have never been able to.
This discovery simply fills a gap in our understanding of the laws of nature that govern all matter, and throws light on what was going on in the early universe. --- Steven Weinberg, Nobel Laureate in Physics
Let's start with the four fundamental forces of nature:
- Electromagnetism (light, radio signals, etc)
- Nuclear Weak force (responsible for nuclear decay, or radioactivity)
- Nuclear Strong force (how particles in the atomic nucleus are held together)
- Gravitational force (keeps us on the mothership)
Scientists believe that these are different manifestations of the same force, and should be represented by just one set of equations. Physicist have been trying to unify these four forces of nature for almost a century.
In 1967, the Nobel Prize-winning physicist Steven Weinberg made the Higgs boson a centerpiece of an effort to unify two of the four forces of nature, electromagnetism and the nuclear weak force (the electroweak force). The discovery of the Higgs Boson puts the unification of these two of the nature's fundamental forces on stronger footing.
The Standard Model of Particle Physics, that describes the basic building blocks of matter, is considered a highly successful theory of science. But it's equations describe particles as massless without the existence of Higgs field. In other words, the standard model would fall apart without the existence of the Higgs Boson, and particle physicists would have to look for alternate theories for the basic building blocks of matter. The discovery thus validates that scientists are on the right track. It is worth mentioning that the Standard Model is not a perfect theory of nature and more research is needed for the model to explain certain aspects of nature that it cannot explain today (the theory explains only three out of the four fundamental forces, omitting gravity).
Further study and experimentation may result in the discovery of more Higgs particles with different properties. Such studies may help explain other big questions in our understanding of nature at the very fundamental levels --- including Supersymmetry, Dark Matter and Dark Energy. (You can certainly read more about these if you're interested). An experimental proof of Supersymmetry, and explanation of the origin and existence of Dark Matter and Dark Energy will be monumental in our understanding of the origin of the Universe. These may even lead to further unification of the fundamental forces.
The Higgs Boson thus opens the door to possibilities that'll further our understanding of the Universe, its origin, and perhaps even its ultimate fate.
But does it have any direct consequence on our everyday lives?
Many of the scientific discoveries weren't much more than of academic interest in the beginning.
Many of the scientific discoveries that enriched our lives in profound ways, originated from discoveries of relatively abstract concepts, that weren't much more than of academic interest in the beginning. Take for example something as common as electricity, that we take for granted today. Steven Weinberg wrote, "At the end of the 19th century physicists in England were exploring the properties of electric currents passing through a near vacuum. Although this was pure science, it led to our knowledge of the electron, without which a large part of today’s technology would be impossible. If these physicists had limited themselves to work of obvious practical importance, they would have been studying the behavior of steam boilers."
Another scientific breakthrough that has eventually led to tangible impacts on our lives is the discovery of anti-matter in the 1930s by Carl Anderson, and now anti-matter plays a very large role in positron emission tomography (PET), which is widely used in medical imaging (e.g., in the detection of cancer tumors).
One more example is the quantum theory, developed near the beginning of the last century. The theory is not only highly abstract, but defies intuition and common sense in many respects. So much so that even Albert Einstein had trouble accepting quantum mechanics as a valid description of reality. But it turned out to be not only one of the most successful theories in science, but one that completely changed our lives. All of modern electronics of semiconductor devices (computer chips etc.) is based on the quantum theory. Without it our societies would be very different today.
The discovery of the Higgs Boson is so fundamental to the laws of nature, said Joe Incandela of the University of California at Santa Barbara (leader of one of the two detector teams at LHC known as CMS) that it could spawn a new era of technology and development in the same way that Newton's laws of gravity led to basic equations of mechanics that made the industrial revolution possible.
Update: October 8, 2013
The 2013 Nobel Prize in Physics Announced
Today the Nobel Committee has announced the recipients of the Nobel Prize winners in Physics.
The Nobel Prize in Physics 2013 was awarded jointly to Belgian physicist François Englert and British physicist Peter W. Higgs "for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider"