Scientific Frontier
At the frontier of physics
At the frontier of physics
As for the six different ?detection chambers?, where the collisions are monitored, the biggest is larger than the Punjab Assembly building, and contains more steel than the Eiffel Tower
A week ago today, the final operational tests were successfully carried out on that monster of a ?machine? known as the LHC (Large Hadron Collider). And the actual experiments are scheduled to begin after some 6-8 weeks.
Did you miss out on this amazing story? Are you wondering what the fuss is all about? If so, let me try to explain, in as non-technical a language as I can muster, why the LHC is the most exciting project for decades in experimental physics; at par, I think, with Eddington?s historic 1919 expedition to the island of Principe, to verify Einstein?s Theory of General Relatively.
No wonder, therefore, that some physicists talk of a new ?golden age? for Physics, as a consequence of experiments made possible for the first time, thanks to the LHC. It is a win-win situation. For, even if nothing startlingly new emerges, the negative implications will still have far reaching consequences for Physics and Cosmology: it will then be back to the drawing board for the theorists.
For, if theory predicts something, and that prediction fails the test of experiment, a big question mark is left overhanging the theory, no matter how elegant it may be mathematically, and how much else it explains satisfactorily. At the end of the day, in the hard sciences, there is no arguing with experimental results. And, for some two decades now, in Physics and Cosmology, fanciful theories have raced far ahead of much needed experimental evidence and verification.
But before I discuss what the objectives are of the experiments to be conducted using the LHC, let me tell you a little about this superlative ?machine?. The LHC is the result of a vast collaborative effort between dozens of countries, hundreds of universities, 8,500 scientists, has been a decade in the making, and cost more than $8 billion (so far).
In simple terms, the ?machine? is what physicists call ?a particle accelerator?. The idea is to accelerate particles to very high velocities (giving them enormous energies) before smashing them together in a controlled collision, and studying the results. In the LHC, the particles are ?protons? ? the basic constituent of the nucleus of every atom ? and two beams are accelerated in opposite directions, each to velocities in excess of 300,000 km per second, before they are smashed together, in six different ?detection chambers?. Incidentally, in physicist taxonomic jargon, a ?proton? is classified as a type of ?hadron?, hence the name LHC.
The proton beams are controlled and accelerated by some 7000 powerful magnets, each weighing some 25 tons. The magnets are cooled by liquid Helium, to just a fraction above the absolute zero of temperature (making the surrounds one of the coldest places in the universe). And, everything is encased in a 12 ft diameter concrete lined circular underground tunnel having a circumference of some 27 km.
As for the six different ?detection chambers?, where the collisions are monitored, the biggest is larger than the Punjab Assembly building, and contains more steel than the Eiffel Tower. The raw data that will be collected can fill up more than 2000 CDs every second. Of course, all this data will take months ? even years ? to analyse fully, by research teams the world over, using thousands of interlinked powerful computers. Will one serendipitous consequence be an ?upgrade? of the world wide web, as we know it today?
So what are physicists hoping to achieve by smashing protons together at previously unavailable energy levels? The short answer (and sorry for a little unavoidable jargon here) is twofold:
First, to explore some vital aspects of the validity of our current theory (known as ?The Standard Model?) about the basic, elementary, constituents of Nature (these being the ?fundamental particles?; and the 4 ?forces? ? gravity, the electromagnetic force, and the ?strong? and ?weak? nuclear forces), from which everything else in Nature follows. And second, to verify some predictions of the ?Big Bang? theory, and other cosmological theories, that underpin our current understanding of the origin and structure of the Universe.
The most important experiment will search for a particle called ?The Higgs Boson?, the only particle postulated by the ?Standard Model? whose existence has not been experimentally verified. What is ?mass? (the physical property that can loosely be defined as every objects? resistance to motion)? And why do the elementary particles have the particular ?masses? they are observed to have? Blame that on the Higgs particle, the theory says. Confirming that this indeed is the case cannot, therefore, be other than crucially important.
But why have we failed to ?find? the Higgs particle hitherto? The answer is that it is a ?heavy? (relatively speaking!) particle. To produce it in the laboratory, therefore, requires the availability of very high energy. Because, as Einstein told us, ?mass? and ?energy? are inter-convertible according to his famous formula: Energy = Mass multiplied by the square of the velocity of light. As the velocity of light is enormous, a huge amount of energy is equivalent to a tiny amount of mass. For the first time, the LHC will provide the needed energy levels.
Other experiments will help validate some important aspects of the ?Big Bang? theory. The collisions will, for a fraction of a second, produce temperatures in excess of 100,000 times that of the Sun. Such temperatures are comparable to those in the early Universe, before it gradually cooled as it expanded.
We can therefore expect (sorry again for some more jargon) to learn what distinguishes the ?electro-weak? and ?electromagnetic? forces of nature, through experiment. Theory says these forces were ?unified? at those higher temperatures in the early Universe. As the Universe cooled, these ?forces? separated to become distinct, by a process known as ?spontaneous symmetry breaking? (this was the Nobel Prize-winning work of Prof Abdus Salam). How precisely this symmetry is broken is central to many questions in cosmology and particle theory. The conditions in the LHC will be conducive for testing such matters.
Current theory has it that some 95 percent of the Universe is composed of mysterious ?dark? matter and energy (?dark? because, as it does not interact with light, we cannot perceive it directly but only indirectly, e.g. through gravitational effects). ?Dark? matter is postulated to be composed of a theoretical particle called a ?Nuetralino?. It may be possible to detect this particle in LHC experiments.
Space constraints prevent me from discussing other planned experiments. Suffice it say that physicists will be kept happily busy for years by the LHC, and I hope you now have some idea of what they hope to achieve.
Are you wondering how many Pakistani scientists, and universities, are involved in the project, either directly or indirectly? I am afraid I do not have the answer to that question.
(The writer is a businessman.)
Munir Attaullah
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