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2014 marks not just the centenary of the start of World War I, and the 75^th anniversary of World War II, but on 29 September it is 60 years since the establishment of CERN, the European Centre for Nuclear Research or, in its modern form, Particle Physics. Less than a decade after European nations had been fighting one another in a terrible war, 12 of those nations had united in science. Today, CERN is a world laboratory, famed for having been the home of the world wide web, brainchild of then CERN scientist Tim Berners-Lee; of several Nobel Prizes for physics, although not (yet) for Peace; and most recently, for the discovery of the Higgs Boson. The origin of CERN, and its political significance, are perhaps no less remarkable than its justly celebrated status as the greatest laboratory of scientific endeavour in history.

Its life has spanned a remarkable period in scientific culture. The paradigm shifts in our understanding of the fundamental particles and the forces that control the cosmos, which have occurred since 1950, are in no small measure thanks to CERN.

In 1954, the hoped for simplicity in matter, where the electron and neutrino partner a neutron and proton, had been lost. Novel relatives of the proton were proliferating. Then, exactly 50 years ago, the theoretical concept of the quark was born, which explains the multitude as bound states of groups of quarks. By 1970 the existence of this new layer of reality had been confirmed, by experiments at Stanford, California, and at CERN.

During the 1970s our understanding of quarks and the strong force developed. On the one hand this was thanks to theory, but also due to experiments at CERN’s Intersecting Storage Rings: the ISR. Head on collisions between counter-rotating beams of protons produced sprays of particles, which instead of flying in all directions, tended to emerge in sharp jets. The properties of these jets confirmed the predictions of quantum chromodynamics – QCD – the theory that the strong force arises from the interactions among the fundamental quarks and gluons.

CERN had begun in 1954 with a proton synchrotron, a circular accelerator with a circumference of about 600 metres, which was vast at the time, although trifling by modern standards. This was superseded by a super-proton synchrotron, or SPS, some 7 kilometres in circumference. This fired beams of protons and other particles at static targets, its precision measurements building confidence in the QCD theory and also in the theory of the weak force – QFD, quantum flavourdynamics.

QFD brought the electromagnetic and weak forces into a single framework. This first step towards a possible unification of all forces implied the existence of W and Z bosons, analogues of the photon. Unlike the massless photon, however, the W and Z were predicted to be very massive, some 80 to 90 times more than a proton or neutron, and hence beyond reach of experiments at that time. This changed when the SPS was converted into a collider of protons and anti-protons. By 1984 experiments at the novel accelerator had discovered the W and Z bosons, in line with what QFD predicted. This led to Nobel Prizes for Carlo Rubbia and Simon van der Meer, in 1984.

The confirmation of QCD and QFD led to a marked change in particle physics. Where hitherto it had sought the basic templates of matter, from the 1980s it turned increasingly to understanding how matter emerged from the Big Bang. For CERN’s very high-energy experiments replicate conditions that were prevalent in the hot early universe, and theory implies that the behaviour of the forces and particles in such circumstances is less complex than at the relatively cool conditions of daily experience. Thus began a period of high-energy particle physics as experimental cosmology.

This raced ahead during the 1990s with LEP – the Large Electron Positron collider, a 27 kilometre ring of magnets underground, which looped from CERN towards Lake Geneva, beneath the airport and back to CERN, via the foothills of the Jura Mountains. Initially designed to produce tens of millions of Z bosons, in order to test QFD and QCD to high precision, by 2000 its performance was able to produce pairs of W bosons. The precision was such that small deviations were found between these measurements and what theory implied for the properties of these particles.

The explanation involved two particles, whose subsequent discoveries have closed a chapter in physics. These are the top quark, and the Higgs Boson.

As gaps in Mendeleev’s periodic table of the elements in the 19^th century had identified new elements, so at the end of the 20^th century a gap in the emerging pattern of particles was discerned. To complete the menu required a top quark.

The precision measurements at LEP could be explained if the top quark exists, too massive for LEP to produce directly, but nonetheless able to disturb the measurements of other quantities at LEP courtesy of quantum theory. Theory and data would agree if the top quark mass were nearly two hundred times that of a proton. The top quark was discovered at Fermilab in the USA in 1995, its mass as required by the LEP data from CERN.

As the 21^st century dawned, all the pieces of the “Standard Model” of particles and forces were in place, but one. The theories worked well, but we had no explanation of why the various particles have their menu of masses, or even why they have mass at all. Adding mass into the equations by hand is like a band-aid, capable of allowing computations that agree with data to remarkable precision. However, we can imagine circumstances, where particles collide at energies far beyond those accessible today, where the theories would predict nonsense — infinity as the answer for quantities that are finite, for example. A mathematical solution to this impasse had been discovered fifty years ago, and implied that there is a further massive particle, known as the Higgs Boson, after Peter Higgs who, alone of the independent discoveries of the concept, drew attention to some crucial experimental implications of the boson.

Discovery of the Higgs Boson at CERN in 2012 following the conversion of LEP into the LHC – Large Hadron Collider – is the climax of CERN’s first 60 years. It led to the Nobel Prize for Higgs and Francois Englert, theorists whose ideas initiated the quest. Many wondered whether the Nobel Foundation would break new ground and award the physics prize to a laboratory, CERN, for enabling the experimental discovery, but this did not happen.

CERN has been associated with other Nobel Prizes in Physics, such as to Georges Charpak, for his innovative work developing methods of detecting radiation and particles, which are used not just at CERN but in industry and hospitals. CERN’s reach has been remarkable. From a vision that helped unite Europe, through science, we have seen it breach the Cold War, with collaborations in the 1960s onwards with JINR, the Warsaw Pact’s scientific analogue, and today CERN has become truly a physics laboratory for the world.

The post Celebrating 60 years of CERN appeared first on OUPblog.

        

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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 (now the British Science Association), Head of the Theoretical Physics Division at the Rutherford Appleton Laboratory, and Head of Communications and Public Education at CERN. His most recent book examines one of the oddest discoveries in physics - antimatter.

In the post below, Frank Close reveals the fallacies concerning antimatter in the Dan Brown novel (and now major cinema release) Angels and Demons. He has previously written for OUPblog on CERN’s Large Hadron Collider.

Many people have never heard of CERN. Of those that have, most know it as the birthplace of the World Wide Web; fewer knew its main purpose, which is as the European Centre for experiments in particle physics. However, with the appearance of Angels and Demons CERN is about to become famous as a laboratory in Geneva that makes antimatter. These two statements about CERN are correct; much else in Dan Brown’s novel, which inspired the movie and has led to much of the popular received wisdom about antimatter, is not.

The movie is of course fiction, but the book on which it is based teases readers with a preface headlined “FACT”. This includes “Antimatter creates no pollution or radiation… is highly unstable and ignites when it comes in contact with absolutely anything… a single gram of antimatter contains the energy of a 20 kiloton nuclear bomb”. CERN is credited as having created “the first particles of antimatter” and the curtain metaphorically rises to the question whether this “highly volatile substance will save the world, or… be used to create the most deadly weapon ever made”.

These “facts” are at best misleading and even wrong, but many, including some in the US military, believe them to be true.

Antiparticles have been made for 80 years; a few atoms of antihydrogen have been made at CERN during the last decade; antimatter, in the sense of anti-atoms organised into amounts large enough to see, let alone contain, is still in the realms of fantasy and likely to remain so.

In Angels and Demons the experimental production of antimatter being equated with The Creation is so central to the plot that a scientist tells the Pope the “good news”, even though it is decades old. Whatever led to our universe, it was not akin to the creation of matter at CERN, in either the fictional or the real world. It is not “something from nothing… practically proof that Genesis is a scientific possibility”. This is at best cod theology and non-science.

The Big Bang is the creation of all energy, all matter, and all of the known universe, together with its space and time. We cannot recreate that singular event, but we can examine what happened afterwards, within what became our present universe.

Energy, lots of it, is what turned into matter and antimatter. Energy is not nothing; it is measurable and when you use some the power company will charge you for it. When you create antimatter together with its matter counterpart, you have to put in the same amount of energy as would be released were they to annihilate one another; you do not get matter from nothing. Now reverse the process, such that antimatter meets matter and is turned back into radiant energy. That certainly is not nothing, as Angels and Demons recognises since the resulting blast is what is going to destroy the Vatican.

It is at this point that some in the US military seem to have adopted this fictional work as its practical guide to antimatter, and to have ignored its many contradictions. The preface of Angels and Demons described antimatter as the ideal source of energy which “creates no pollution or radiation and a droplet could power New York for a day”. Antimatter may not emit radiation so long as it stays away from matter, but in that case it offers nothing to bomb makers or power companies. In order to exploit this “volatile” substance, you need to annihilate it with matter, at which it releases its trapped energy as radiation such as gamma rays.

The statement that there are “No byproducts, no radiation, no pollution” is ironic given that it occurs within a few paragraphs of a warning to beware of the gamma rays. The US Air Force were enthused so much that in promoting their interest in antimatter for weapons they announced “No Nuclear Residue”. The media trumpeted that “a positron bomb could be a step toward one of the military’s dreams from the early Cold War: a so-called `clean’ superbomb” San Francisco Chronicle 4 October 2004, uncanny examples of fiction, written in 2000, presented as if fact in 2004.

As a major milestone in antimatter science CERN is indeed marvellous, but trifling compared with what would be needed to make antimatter in industrial quantities. Even were it possible, the belief that antimatter technology could “save the planet” is specious. As we first have to make the antimatter ourselves, we would waste more energy in making it than we could ever get back, so antimatter is not a panacea for “saving the planet”. Thankfully, neither will it become “the most deadly weapon”.

Antimatter is much loved by science fiction writers. Yet it is real: there are looking-glass particles that are counterparts of protons, electrons, and other familiar particles of matter. Below is an excerpt from Frank Close’s new book Antimatter, which explains that to even begin to understand antimatter you have to first look at the material world, including ourselves. Frank Close previously wrote for OUPblog on CERN’s Large Hadron Collider.

If you were to see a lump of antimatter, you wouldn’t know it; to all outward appearances it looks no different to ordinary stuff. So perfectly disguised that it is seemingly one of the family, its ability to destroy whatever it touches would make it the perfect ‘enemy within’. So, what is antimatter? Saying that it is the opposite of matter is easy on the ear, but what actually is ‘opposite’ about it? Knowing that the briefest contact with antimatter would commit whatever it touched to oblivion is awe-inspiring, but what gives antimatter this power?

To begin to understand antimatter, we need first to take a voyage into ordinary matter, such as ourselves. Our personal characteristics are coded in our DNA, miniature helical spirals made of complex molecules. These molecules in turn are made of atoms, which are the smallest pieces of an element—such as carbon or hydrogen or iron—that can exist and still retain the characteristics of that element.

Hydrogen atoms are the lightest of all and tend to float up to the top of the atmosphere and escape. For this reason hydrogen is relatively rare on earth, whereas in the universe at large it is the commonest element of all. Most of the hydrogen was made soon after the Big Bang and is nearly fourteen billion years old.

Vast balls of hydrogen burst into light as stars, such as our sun. It is in the stars that the full variety of elements is fashioned. Nearly all of the atoms of oxygen that you breathe, and of the carbon in your skin or the ink on this page, were made in stars about five billion years ago when the earth was first forming. So we are all stardust or, if you are less romantic, nuclear waste, for stars are nuclear furnaces with hydrogen as their primary fuel, starlight their energy output and assorted elements their ‘ash’ or waste products.

To give some idea of how small atoms are, look at the dot at the end of this sentence; it contains some 100 billion atoms of carbon, a number far larger than all humans who have ever lived. To see any of those individual atoms with the naked eye you would need to magnify the dot to be 100 metres across.

Elemental carbon atoms can bind in different forms, such as diamond, graphite, and carbon black—soot, charcoal, and coal. Antimatter also consists of molecules and atoms. Atoms of anticarbon would make antidiamond as beautiful and hard as the diamond we know. Antisoot would be as black as soot, and the full stops in an antibook the same as those you see here. They too would need enlarging to 100 metres size for their anticarbon atoms to be seen. Were we able to do that, we would find that these smallest grains of anticarbon are indistinguishable from those of carbon. So even at the basic level of atoms, matter and antimatter look the same: the source of their contrast is buried deeper still.

Atoms are very small, but they are not the smallest things. It is upon entering them and encountering the basic seeds from which they are made that the profound duality between matter and antimatter is disclosed.

Each atom contains a labyrinth of inner structure. At the centre is a dense compact nucleus, which accounts for all but a trifle of the atom’s mass. While enlargement of our ink-dot to 100 metres is sufficient to see an atom, you would need to enlarge it to 10,000 kilometres, as big as the earth from pole to pole, if you wanted to see the atomic nucleus. The same is true for antidots and antiatoms. It is only when they are seen in such fine detail that the subtle choice of matter or antimatter begins to show.

When the profound entangling of space and time that comes with Einstein’s theory of relativity is married with the will-o’-the-wisp ephemeral world of uncertainty that rules within atoms, an astonishing implication emerges: it is impossible for nature to work with only the basic seeds of matter that we know. To every variety of subatomic particle, nature is forced also to admit a negative image, a mirror opposite, each of which follows the same strict laws as do conventional particles. As the familiar particles build atoms and matter, so can these contrary versions make structures that at first sight appear to be the same as normal matter, but are fundamentally dissimilar.

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.

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