Big Answers With A Big Bang
Frank Close, OBE, is Professor of Physics at Oxford University and a Fellow of Exeter College. He was formerly vice president of the British Association for the Advancement of Science, Head of the Theoretical Physics Division at the Rutherford Appleton Laboratory, and Head of Communications and Public Education at CERN. He received the Institute of Physics’ Kelvin Medal in 1996, awarded for outstanding contributions to the public understanding of physics. He is the author of The Void, Very Short Introduction to Particle Physics, The Particle Odyssey and many more. Also, look for Antimatter in January, Close’s newest book.
We asked Close to explain the importance of the Large Hadron Collider to us. He kindly sent us the post below and the following analogy, comparing the journey for answers about the origin of the universe to sewing a tapestry: “The quest is like sewing a tapestry, but one where the picture is only revealed as you do so. First you have to make a needle, then feed it with thread and then finally start sewing. It took 20 years to design and build the needle. Last Wednesday we started to put thread through the needle’s eye. It will take some time before we have enough thread, tightly enough wrapped and in sufficient colors to start sewing. That will be later this year or next spring. If we are lucky there may be some parts of the picture where the image quickly comes clear; other parts of the picture may take a lot of time and careful work before the images can be discerned.”
Keep reading to find out the answers this tapestry may hold.
Only nature knows what happened in the long-ago dawn of the Big Bang; but soon humans will too. The visions of the new world will hopefully be tomorrow’s stories. If you want a machine to show how the universe was in the moments of creation, you don’t find it in the scientific instrument catalogs: you have to build it yourself. And so scientists and engineers around the world pooled their knowledge to build the Large Hadron Collider (LHC).
Immediately there were problems. Beyond the ability of a single continent, this became a truly global endeavor; unparalleled in ambition, in political and financial challenges. At its conception, the state of the art in cryogenics, magnets, information technology, and a whole range of technologies was far short of what would be required for the LHC to work. The whole enterprise relied on the belief that bright ideas would emerge to solve problems, any one of which could have proved a show-stopper. There were many who feared that particle physics had bitten off more than it could chew; that the LHC was over-ambitious; that this would be the end of physics.
Now we are almost there. Wednesday, Sept 10 when the current was turned on, and for the first time a beam of protons circulated through the vacuum tubes colder than outer space, was just the start. The next step will be to send two beams, in opposite directions – well, that’s been done but not yet intensely enough to smash into one another and produce data. That is still for the future. At first, and for some months, they are likely to be too diffuse and low energy to produce anything of great use to science. Only later when high energy intense beams collide, and the debris from those mini-bangs pour through the gargantuan detectors, which in turn speed signals to the waiting computers, will the moment we’ve waited for have arrived. A year or two accumulating data and the first answers to the big questions will begin to emerge.
The seeds of matter were created in the aftermath of the Big Bang: quarks, which clustered together making protons and neutrons as the newborn universe cooled, and the electron, which today is found in the outer reaches of atoms. We and everything hereabouts are made of atoms. In the sun and stars intense heat rips atoms apart into their constituents, electrons, protons and neutrons.
By colliding beams of particles, such as electrons or protons, head-on, it is possible to simulate the high-energy hot conditions of the stars and the early universe. At CERN (European Council for Nuclear Research) in the 1980s a machine called LEP (Large Electron Positron collider) collided electrons and their antimatter analogues, positrons, fast enough that they mutually annihilated and created for brief moments in a region smaller than an atom, the conditions that occurred within a billionth of a second of the Big Bang. Trying to reach time zero is like finding the end of the rainbow, and the LHC will take us ten to a hundred times further than ever before. At the LHC the beams of protons will pack a bigger punch and their collisions will show how the universe was at its infancy and perhaps give us some insight to how the universe evolved.
Within a billionth of a second after the Big Bang, the material particles from which we are made, and the disparate forces that act on them, had become encoded into the fabric of the universe. However, the events that led our universe to win the lottery of life were decided earlier than this. Some of them we believe occurred in the epoch that is now within our reach. That is what the LHC promises to reveal.
As the 21st century begins, physics can explain almost all of the fundamental phenomena revealed in the search for our origins, yet there are niggling loose ends. We see hints of a unified theory vaguely in the shadows, but what it is and how the structures that led to the particles and forces that molded us are still perceived only vaguely.
Why are there three spatial dimensions; could there be more? Cosmology suggests that “normal matter” is but one percent of the whole, and that we are but flotsam on a sea of “dark matter”. What that dark sea consists of, how it was formed, why there is any matter at all rather than a hellish ferment of radiation, are unknown.
Why is there structure and solidity to matter when our theories would be happier if everything flitted around at the speed of light? Theorists believe that all structure and ultimately the solidity of matter are the result of a field of force that today permeates the universe known as the Higgs field. This can be made to reveal itself if the conditions are right. For example, as an electromagnetic field can be stimulated to send out electromagnetic waves, so can the Higgs field create waves. However to create these waves requires huge energy. The LHC has been designed to achieve these conditions. As an electromagnetic wave comes in quantum bundles, particles known as photons, so the Higgs waves will come in the form of particles known as Higgs bosons.
There is also the question: why there is anything at all? In the beginning there was nothing: “there was darkness on the face of the void”. Then came a burst of energy: “let there be light and there was light”, though from where it came no-one knows. What we do know is what happened next: this energy coagulated into matter and its mysterious opposite, antimatter, in perfect balance. Anti-matter destroys anything it touches in a pyrotechnic flash. So how did the early universe manage to survive self-annihilation between the newly born matter and antimatter? Something as yet unknown must have occurred in those first moments to upset the balance. For several years we have glimpsed a subtle asymmetry between arcane forms of matter and antimatter made from “strange” and “bottom” quarks and antiquarks. One of the goals of the LHC will be to produce large numbers of particles of bottom matter and their antimatter counterparts in the hope of finding the source of the asymmetry between matter and antimatter.
Ultimately however, this is a voyage of discovery into a world that once existed but was lost in the sands of time, 13.6 billion years ago. Like some astonishing Jurassic Park, the LHC will show once more what that epoch was like. We have ideas of what is to be found, and there are certainly questions, such as those above, whose answers we crave. But in focusing on them like this we are getting ahead of ourselves. We are at the stage of witnessing remarkable engineering, and it is those we should be applauding; as for discoveries in fundamental science – watch this space.