There are fears that 'tampering with nature' could result in Earth being annihilated or hideously transformed
THE LARGE Hadron Collidor (LHC) began operations on September 10th in a blaze of publicity. The LHC is a massive particle-accelerator designed for fundamental physical research. Scientific research goes on every day worldwide but it rarely attracts such publicity. Why is the LHC so noteworthy? There are at least three reasons: the LHC grabs the imagination because the machine is so massive, because the questions it will tackle are so fundamentally important, and because fears have been raised that the LHC experiments are so dangerous that our world could be destroyed.
The LHC is an international project based at Cern (European Organisation for Nuclear Research) in Geneva, in which 111 nations (but not Ireland) are participating. The LHC is the most powerful in a series of particle colliders that have, over the last 70 years, probed the nature of matter and looked ever further back in time.
The LHC collides hadrons and studies the effects produced. It will recreate, on a micro-scale, conditions that existed billionths of a second after the birth of universe.
So, what are hadrons? Hadrons are subatomic particles made of quarks, held together by the strong nuclear force, mediated by gluons, the carriers of the force. The proton and the neutron are the most familiar examples of hadrons. Proton beams will be accelerated to enormous speeds in the LHC and then smashed together.
The machine weighs more than 38,000 tonnes and runs for 27km in a circular tunnel 100m below the Swiss/French border at Geneva. Four massive detectors are located around the tunnel and a global network of computers will analyse the data recorded by the detectors. Two separate particle beams circulate around the tunnel and are collided. The detectors record the particles scattered in all directions when the particles collide.
The universe originated about 14 billion years ago in an unimaginably energetic explosion called the Big Bang. Ever since then the universe has been expanding, cooling down and becoming less energetic. The familiar matter and the four fundamental forces of our world froze out of this ball of energy very early in the cooling process. The colliding protons in the LHC will recreate tiny patches of the energy that existed billionths of a second after the start of the Big Bang, allowing physicists to better understand the nature of matter and fundamental forces.
Many physicists think the universe has more dimensions than the four familiar ones (length, breadth, depth, time). The LHC may produce evidence of these extra dimensions, such as mini black holes that appear and disappear in a fraction of a second. Gravity is least understood and easily the weakest of the four fundamental forces. One possible explanation is that our universe is part of a larger multi-dimensional reality and gravity leaks into these other dimensions making it seem weaker.
Equal amounts of matter and antimatter were generated in the Big Bang but all the antimatter has disappeared - what happened to it? One of the LHC experiments will study this question.
Particles of matter such as protons and neutrons have mass whereas particles of light (photons) have no mass. Why is this? Physicist Peter Higgs proposed that a field permeates the universe and interacts with some particles to give them mass. If high enough energies are produced, this field should be detectable as a particle (the Higgs' particle) and the high energies of the LHC should be sufficient to reveal it.
Immediately after the Big Bang quarks and gluons existed separately at a temperature more than 1,000 billion degrees. When the temperature fell to 1,000 billion degrees the quarks and gluons combined to form particles like protons and neutrons. The LHC project will also collide nuclei of lead atoms so that for an instant they release quarks thus taking us back to the earliest phase in the evolution of the universe.
Physicists understand only 4 per cent of the matter in the universe. Much of the remaining matter is called "dark matter". One theory proposes that all known matter particles have as yet undetected "super partners" and, if they exist, the LHC should be able to find them. It is possible that dark matter is composed of super symmetric particles.
Fears have been voiced that the LHC experiments are catastrophically dangerous. One fear is that the LHC might generate a black hole that would swallow the earth. Another fear is that the high energies generated might create theoretically conceivable particles called "strangelets", particles of matter whose configuration of quarks makes them strange compared to ordinary matter.
Under certain circumstances such strangelets could catalyse the transformation of Earth into an inert lump of strange matter. Cern has declared that these fears are groundless. So, don't worry, you are already as strange as you are going to get.
• William Reville is associate professor of biochemistry and public awareness of science officer at UCC - www.understandingscience.ucc.ie