Sunday, October 24, 2010

The Large Hadron Collider

In the Waves Physics course that I teach, the students regularly enter the lab to perform a fairly rudimentary experiment that aims to prove a certain law introduced during a lecture.  Today, for example, the students will be playing with thin, converging lenses, and proving that the image of an object may be real or virtual, depending on whether the object is located inside or outside the focal length of the lens.  This simple Optics experiment involves light, but it surprises my students to learn that man, even today, with all its fancy gadgets, does not know the true nature of light. 

We know a lot more about light than our ancestors did two hundred years ago.  We know that it behaves like an electromagnetic wave, travelling through the void of space at about 300,000 km/s.  Light was Albert Einstein’s lifetime muse, and led to his most important discoveries: special relativity, E = mc2, and general relativity.  Einstein was disturbed by quantum physics, and wished to quantify light without it.  Today, physicists are struggling to connect Einstein’s general relativity to the accepted, but incomplete study of quantum physics.  They wish to develop a “Unified Theory,” or, one equation for everything.  In order to do so, they need to find and determine the behaviour of all of the elementary particles that make up the matter in the Universe.

Although the Universe is composed of the elements in the periodic table, these elements are not elementary particles.  An elementary particle, by definition, is not composed of smaller building blocks.  All atoms are composed of protons, neutrons and electrons.  Scientists today believe that electrons are elementary particles, but do not believe that protons or neutrons are.  Today, thirty-eight countries and three thousand scientists are working together, wishing to study the dozens of theoretical elementary particles, like those that may comprise a proton, by means of the most expensive Physics experiment ever developed: The Large Hadron Collider (LHC). 

Built in 2008, one hundred metres below the surface in Geneva, a circular pipe, two inches in diameter, and twenty-seven kilometres long, contains particles that are accelerated by magnets to nearly light speed in opposing directions.  The inevitable collisions of these particles have an inherent high energy density associated with them.  The energy is so great, that mass is created as a result of them.  How much mass is created?  E/c2 kilograms are synthesized, as predicted by Einstein.  What does this mass consist of?  It consists of elementary particles, which seem to come from nowhere.  In fact, they do come from nowhere: it is believed that the Universe expands freely over time.  With this in mind, the Big Bang may be viewed as a natural occurrence.  At the LHC site, a one-billion-dollar camera, the ATLAS Detector, takes 3D pictures at a specific location along this pipe where collisions are orchestrated.  The camera is designed to detect elementary particles that are created due to the collisions.  The ATLAS is the size of a six-storey building.  The camera is at the current forefront of engineering technology, but will no doubt come standard with the iphone 6.

By studying these photographs and understanding the particles involved in the collisions, physicists are beginning to extend their understanding of life’s building blocks.  If we learn more about the building blocks, we can learn more about the nature of life during the early stages of the Big Bang, and answer important questions, like what is dark matter composed of?  The world’s most prominent physicist, Stephen Hawking, believes that we may develop a Unified Theory during the twenty-first century.  If this comes to fruition, it will be man’s crowning achievement to that point.  It will be the final answer to “What is the Universe?” and “How does the Universe behave?”  The unified theory may become common knowledge to the public, taught in High Schools across the Planet.  Then, the public can, with a more solid foundation to stand upon, ask the most compelling question of all, “Why?”
Before getting ahead of ourselves, we must examine the current state of the LHC experiments.  Nine days into operation, the LHC had to be shut down for maintenance.  Some magnets were repaired and others were replaced.  Today, the experiment is operating smoothly at 50% of its maximum designed capability.  To date, the greatest detected collisions have generated 7 TeV (seven million million electron-volts).  Many collisions have been photographed, and many elementary particles have been observed, though in an incomplete sense.  That is to say that while such particles have left an “energy trail,” they have not been observed in an up close static sense.  Thus far, the experiment results have agreed with current theories in quantum mechanics.  In about two years, the LHC will be run at its maximum capacity.  Higher energy collisions will likely allow physicists to observe never-before-seen particles.  If you are a physicist involved in research today, the LHC site is the place to be.
In addition to being a very expensive project (ten billion dollars to construct, and a massive monthly electric bill to operate), the LHC is one of the most ambitious and intriguing projects currently ongoing.  By comparison, the lens lab that I am helping my students conduct today feels more than a little dull.  Still, these budding science students need to start somewhere.  The physicists of tomorrow will be working with the Large Hadron Collider and other groundbreaking experiments.
It is interesting that our most important discoveries may come from smashing stuff together.  It is quite a leap from our ancestors smashing two rocks together and observing the sound. It is also rather telling that the LHC, our coolest project ever, is buried one football field length below the surface.  It is akin to a squirrel burying its most treasured nut.  The choice to bury it was made out of feasibility, as a 27 km track above the surface near any civilization would interfere with roadways and be unnecessarily exposed to the outdoor elements.  Still, its location has a certain irony.  It appears that the maker of our Universe has hidden its most compelling secrets very well.  It follows that our search for answers, our attempt to unravel life’s mysteries, should be spearheaded in a remote and hidden location.  Man may yet uncover what truly lies below the surface.

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