Many people have been introduced to the concept of antimatter by reading Dan Brown`s novel Angels and Demons or by seeing the Startrek series on the tv in which space travel is possible by antimatter propulsion. Many people wonder if there is any such thing as antimatter, and whether it can indeed be harnessed by the human race. We are on the verge of space exploration but the distances are so enormous that man will never set foot on the distant worlds - unless some new form of energy enabling vast distances  to be covered well within  a human lifetime is discovered and made usable. The following essay attempts to answer these questions.

MATTER and ANTIMATTER

 Section One

 In September, 2002,  American newspapers presented headlines about European physicists achieving a “major breakthrough” in a long struggle to understand a very strange and mysterious substance : antimatter,  which permeates the universe, and which is so called   because it is like a mirror image of ordinary matter. These scientists had succeeded in creating “anti atoms” , the “looking glass cousins” of normal atoms . In particular, anti-atoms of hydrogen , the substance that largely powers the sun, but which may be better known to us as the means of inter-stellar propulsion in the tv series ,Star Trek. In hydrogen, , the simplest element, a negatively charged electron orbits a proton nucleus ; but in an antihydrogen atom a positively charged particle  - a positron  - orbits an antiproton nucleus.. Anti-matter , like ordinary matter is composed of electrons and protons but with an electrical charge.. An normal electron has a negative electrical charge, while protons are positively charged. In anti-matter charges are reversed Protons make up the nucleus of the hydrogen atom and have an electrical charge equal and opposite to that of the electron . A positron is the name given to an  electron`s anti-matter counterpart. 

Matter and anti-matter are antipathetic; in other words, if they collide , they annihilate each other in a burst of tremendous energy. Harnessing this energy would revolutionise life on earth and in space.. The atom bomb is a minor instance of this – but for destructive purposes.  Summing up, matter that occupies space consists of atoms and subatomic particles called protons, neutrons and electrons. For each basic particle , there is a corresponding antiparticle. A neutron is a particle that is neutral electronically and with the same mass as a proton.

First of all, a little bit of history! In 1928 , a British physicist, Paul Dirac, formulated a theory for the motion of electrons in electric and magnetic fields. These theories included some of Einstein`s work on the Theory of Relativity, and led Dirac to “discover” many attributes of electron motion that previous study could not. His theory led  to the prediction that the electron must have an antiparticle but which had  a positive charge. All particle research since then has resulted from Dirac`s breakthrough. Of great moment is the fact that thousands of atoms made entirely of antimatter had been produced. This alone gave the world the message that limitless energy might indeed open up to us, from “domestic” use (mainly in medical contexts) to space exploration. Not only this, but the “discovery” of the properties of antimatter .might also give insights into the beginnings of the universe.   Nothing could have been more exciting at the time. The point about antimatter is that it is impossible to tell the difference by looking between it and its  twin, regular matter. The only difference is, as stated above, that antimatter has an opposite electrical  charge  to “normal” matter. We have stated that enormous amounts of energy are generated by annihilation when antimatter and  matter come into contact, giving rise to fears of danger, but small  amounts are not dangerous. Much of the development of research in this field is undertaken by the European Centre for Nuclear Research , , known by its (French) acronym of CERN, in Switzerland. At immensely high speeds , protons are accelerated which results in the creation of both matter and antimatter particles. Millions of accelerated protons are needed to produce one particle  of antimatter. But millions are accelerated.The problem is that the atoms of hydrogen so produced have a very short life indeed, millions of a second. And they move at great speeds!  - making their study very difficult. How to slow then down? The scientist built a machine to do just  this – and enabled them to study the elusive antiatoms.

The holy grail of sub-atomic research lies in resolving the puzzle of why the (our) universe is seemingly made up of matter rather than of antimatter since our understanding of the orgins of the universe lead us to think that it (the universe)  should be made up of equal amounts of matter and antimatter. (It was  providential that this was not so as a mix of antimatter particles and regular matter particles would have resulted in the complete annihilation of all matter – and subsequent life would have been out of the question). What happened as far as we can tell, was that indeed matter and antimatter were created equally , but for some (so far) unknown reason one particle of matter  extra,  was produced  and this remained over as it were after the process of annihilation  (matter versus antimatter) out of which the universe was formed. Clearly, there was some sort of imbalance  in that first millisecond at the dawn of creation. We do not know why but the breakthrough at CERN may result in an explanation as research continues into the behaviour of antimatter.

Section two

Research into atomic particles has therefore great implications for the future. For example the harnessing of antimatter would mean that space exploration to distant  worlds would be possible. A gram of antimatter would enable the journey to Mars, for example, to be made in about two weeks instead of two years as at present. As stated, when matter particles come into contact with antimatter particles , they annihilate each other and loose energy that is millions of times greater than that produced by conventional combustion or explosion. However. as we have seen,  antimatter is created with great difficulty and is even more difficult to keep, because of its volatility. Producing and storing a gram of antimatter is the present goal, and to put this in context  we need to know that  the world`s largest maker of antimatter (Fermi National Accelerator  Laboratory) makes only a fraction of a gram a year. At that rate it would take about a million years (for now!) to produce a gram, and this would not be anywhere near  enough to power a spacecraft.

By contrast, antimatter is being used now to treat diseases, and will do more so in the future. At the moment , its application is more widely seen in medical imaging systems. (for diagnoses). It could for example. kill cancerous tumors. The process is explained by realising that when a proton meets an antiproton it will produce a lot more energy to the tissue under examination than conventional methods. At low energies annihilations  (between electron and positron) are put to medical uses, to reveal, for example, workings of the brain, by means of the technique known as Positron Emission Tomography (PET). Hence the headline seen in summer, 2005, “Grey matter made visible with invisible antimatter”. The process is too involved to go into here, but the nub of it is that gamma rays are produced which can be detected and used to build up an image of the organ being investigated, while the patient is still conscious. This may lead to cures for such as Parkinson`s disease and the alleviation of Alzeimers disease. The use of PET means that it scans bodily processes unlike say, x-rays which look at the body itself, passing through skin but not through bone. CAT scanning is quite well known  and basically interprets all the x-rays and combining them into a coherent image. There are other methods as well for investigating the body, such as ultrasound imaging and Magnetic Resonance imaging. So the PET technique is different and full of promise. Put simply, PET patients are given radio active tracers, which when they decay,  they emit positrons which annihilate with the electrons in the body , producing the gamma rays mentioned above, whose movement permits the PET scanner to diagnose where the centre of the ailment is.

Cancer treatment can be revolutionised as the latest interest is in using particles (instead of x-rays, for example) . Beams of protons, neutrons and ions (electrically charged atoms) , hold advantages over x-ray radiotherapy. Particle therapy works by attacking the DNA of cancerous cells by ionization .  This means that tumours can be targeted more accurately. The trouble is that x-rays are comparatively cheap, particle beams are not.

However, many patients have been successfully treated by the “new” system , but the technique still has some way to go before it becomes routine. Charged particles , ions and protons , are not the only way to attack tumours. Neutral particles can be even more effective, having a higher energy transfer than charged particles. Indeed, some companies are turning to antimatter as a potential form of particle therapy. They employ antiproton beams to investigate the effects of antiprotons in biological material/tissue

Another very important question arises from all this. If particles of antimatter and normal matter annihilate on contact,, can there be any antimatter left in the universe? Certainly

 there are very violent  reactions taking place in the universe. Does this denote the presence of antimatter? So far, we have to manufacture it. A very very long and elusive process. But this does not mean we cannot anticipate! We have mentioned Einstein in relation to Dirac`s work. Einstein`s famous equation : E=mc2, is the key to understanding: when antimatter annihilates, all is converted to energy, which greatly exceeds the energy output of burning oxygen and hydrogen in Shuttle rockets.

However, when we look around or indeed conduct experiments, we are aware  that ordinary matter dominates the universe – or what we know of it. We have mentioned earlier that there must have been an imbalance in the (incalculable) numbers of particles in the first fraction of a second of the universe`s life. One notable physicist puts it this way: “it is possible that the theory of how the matter-antimatter asymmetry in the universe built up may need modification. But either way, we win because there is something that we don`t fully understand about the universe and therefore , there is something new to be found."   .  What we do believe (not know) is that essentially all the objects we see in the universe are made of matter not antimatter. Antiparticles are created in the universe where there are high-energy particle collisions , such as in the centre of our galaxy. but none has been  detected as left over from the “Big Bang”.

In science fiction, in such as Star Trek, antimatter is seen as the ultimate fuel , with its convertibility to energy. It may be that antihydrogen atoms will produce not only a means of space travel, but will reveal a different mathematical universe  - in which positive is negative and left is right. A parallel universe?  The Big Bang theory is of course the favourite explanation at present for the origin of the universe. Original particles began to enter space about 30 billion  years ago, and began the three dimensional aspect that we know now. By about 12 billion years ago , these particles had begun to create the  “Primal aggregate” of the Big Bang theory.

To give some idea of the costs involved, the present estimate is that it is possible to produce antimatter for about $25 billion per gram, roughly 1000 times more costly than present space shuttle propellants. The Wikipedia encyclopedia points out that thrust to weight equations in antimatter used in rocketry would enable an unmanned craft to reach Mars in about a month, instead of about a year in conventional terms. A concomitant could be that humanity would have the capability to make antimatter weapons!! 

Section 3

Antimatter is created in the universe , as we have said: it is created in stars, like our sun, every day. In the sun , flares accelerate fast moving particles which collide with slower particles producing antimatter. Therefore it is possible to see antimatter as a natural but very mysterious thing. As Wikipedia comments , fictional portrayals  of mirror-image  objects have not been proven unsustainable. We cannot rule out the possibility  that some antimatter star or galaxy exists somewhere.  As we have stated above, collisions and annihilations are the essence of our topic. We hope that in future,  space craft propulsion will be realisable. But before then we need to learn how to produce a sufficient amount of antimatter, how to store it, and how to utilise the energy in thrust to propel a starship. As a BBC article (h2g2) of 2001 says so concisely, annihilating a kilo of antimatter with a kilo of matter, would release the amount of energy contained in 28 million barrels of oil, but it would take a lot more than this to produce a kilo of antimatter. If direct antimatter drives are possible , we are light years away from building one. (!)  But this fact does not stop the human race from trying to develop what we know and have. It is a fact for example that a particular government  (USA) is trying at this very moment to develop future weapons based on antimatter. Super bombs for instance would render an enemy defenceless. If such bombs were eventually able to be produced , the version developed  would not eject radioactive debris. The main difficulty is, as we have noted, the storage of the antimatter particles – after they have been produced!  However, progress is being made – but kept under wraps (by governments). Both military and air force arms of “defence” are investigating the potential of antimatter. We can end this section by quoting one of the scientists prominent in the research. “We need to get off this planet, because I`m afraid we`re going to destroy it.” (Head of Washington State`s Centre for Materials Research). A telling comment, indeed.

At this juncture it is opportune to say a word or so about CERN, which has been mentioned earlier. CERN is mainly located in Switzerland, near Geneva, and its purpose, to reiterate, is to provide the particle accelerators needed  for high energy research. As it happens, the WWW began as a CERN project, initiated by Tim Berners-Lee in 1980. The first web site went on line in 1991 and in 1993 the Web became universal. CERN produces antimatter, by means of high energy  collisions to generate particles  and their     

Antiparticles. As the Exploratium article of a few years ago, said memorably, “in their [CERN scientists] search for that elusive mechanism that would  help explain the mystery of why we are here, physicists might discover something totally unexpected.

 , opening the door  to an amazing new discovery no one has yet imagined.”  The CERN scientists are looking at how the universe would look if it was made out of antimatter. Would there be the slightest difference?  - a comment and question made by a CERN spokesman. The fundamental fact to remember is that we need to manufacture antiatoms as the next step to understanding the basic properties of an antimatter world. A spokesman for the FERMI NATIONAL ACCELERATOR LABORATORY , near Chicargo  (does the same sort of work as CERN) says that to understand whether this mirror world is out there , you have to test its ingredients and see if they behave the way we would expect them to behave. [Exactly!]. .  .

Theoretically, a reaction could be contained if the collision could be slowed down. Then it may be that it could be used to power vehicles. And the nearest stars could be “in reach” that are trillions of miles away. As we know, antimatter developments are not only in pursuit of space travel, but for potential use for military robotic aircraft and even for sensors to detect terrorist weapons. Robotic aircraft powered by antimatter could reveal the whereabouts of enemy forces, by means of remote tv . As an American newspaper report graphically put it, reiterating the power of antimatter, a millionth of a gram of antimatter contains enough energy  to propel an aircraft three times around the world without refuelling. But as stated the main difficulty is storage of antimatter particles. Not all however is pessimistic: positrons and antiprotons can be stored in a device known as a Penning Trap which uses a combination of  magnetic and electric fields to hold charged particles in a vacuum. This is however in the early stages. Several establishments are engaged in relevant researches; one of these is NASA, one of whose studies is focussing on whether the antimatter that occurs naturally in the Van Allen belts of earth and in the gas giant planets, such as Jupiter and Saturn, might be able to be  collected  with magnetic scoops at lower cost per gram  by present means.  

Comets do contain antimatter. Their bright areas produce light because of matter and antimatter annihilations. Their  nucleus is composed of stony and iron antimatter. Its mass is of the order of probably billions of tons of antimatter. The bright “head” of the comet we can see in the sky is called the coma which is really a plasma composed mainly of interstellar dust  and antimatter ions. The Oort Cloud , source of the comets, would be reachable by means of an antimatter drive – a journey of some 50 years; nothing compare with today`s thousands . Of course, the ultimate goal of man is FLT (faster than light) propulsion. Whether it will ever be attainable  is a matter for speculation – at the moment! If attainable it will be by means of  antimatter. Antimatter rockets work much like regular fusion drives but with differences. Instead of having a fusion reaction in a magnetically sealed combustion chamber , the antimatter drive mixes antihydrogen with hydrogen for a power output much higher than fusion.   

The  storage problem is maybe the greatest difficulty facing antimatter scientists. Unfortunately outer space seems to be best (though obviously difficult!) and also for extensive production. On Earth, gravity will pull antimatter into disastrous contact with matter. On Earth, gravity has the opposite effect on antimatter i.e. antimattter is repelled by the gravitational force due to its opposite nature to that of matter. As we know, CERN is trying to find a solution to the gravity problem. We have mentioned the fundamental difficulty in understanding the matter- antimatter dichotomy : one theory put forward in an attempt to explain the seeming overwhelming presence of matter, is that the universe divided into two parts after its formation: our universe and an alternative universe of antimatter that cannot be seen by us. Research and advance into antimatter is not without its dangers of course. As an Encarta article states , discovering antimatter could mean the end of the Earth as we know it. One mistake could mean the release of high energy gamma rays that could wipe out the life on Earth in minutes. At present, we could (somewhat flippantly) summarise the (research) position by saying it is a race to see who can make the first antimatter element. At the moment, it (antimatter) is the most expensive substance on Earth;  as the article says, about $62 trillion a gram!  A CERN physicist states that “our goal is to remove antimatter from the far-out realm of science fiction into the commercially exploitable realm for transportation and medical applications”.

Another theory advanced is that in separate clusters of galaxies, antimatter and matter are  located. It however must be admitted that our present understanding of the universe cannot explain the apparent striking imbalance between antimatter and matter if both had been created ab initio. The presence of large amounts of antimatter in the universe cannot be ruled out at present, nor can intense radiation which might be due to antimatter-matter collision. It may be that quasars are so visible and bright because of the existence in them of antimatter . They emit tremendous energy from a small volume of space, too great for physics to explain it.

Section 4

The first television fiction show appeared in  1966: “Star Trek”, featuring the Starship Enterprise. It soon became very popular, featuring the adventures of the crew of Starship Enterprise on its mission to explore outer space. In order to travel at speeds greater than light the Enterprise was equipped with “Warp Drive” , a hypothetical propulsion system that warps space  so that distances between stars are greatly reduced. The Enterprise had faster than light engines powered by antimatter. With warp drives the space ships could reach far  stars  in hours or days , making possible stories that could fit human lifetimes. With warp drive the ships could reach distant stars in hours or days, fitting human adventures. Roddenberry, the science fiction writer, managed tp keep the stars realistically far but imagined human beings able to reach them . The mixing of matter and antimatter is the power source used by the spaceship whereby the antimatter  (frozen anti hydrogen) is managed by magnetic fields , and never allowed to touch normal matter.Another possibility is the creation of rocket engines based on fusion reaction.

  . Included in the science of startrek is the creation of a device which uses a beam radiated from one point to another where it stops at just the right place, and reconstructs the person it carries on the spot. Or it dematerialises the person and brings him or her to some other point. All is still in the correct positions and adhering together  as if the transportee had not been dematerialized.

            Some time ago an exhibition at the Science Museum in London, (among many other things) explained the differences between matter and antimatter and how their combination might one day power a spacecraft, like the Enterprise. At the moment, however, antimatter is impossible to store  However, physicists are at present working on ways of storing antimatter particles , especially antiprotons for use as a power source for spaceships, by which antimatter is used as a heat source. May I be forgiven for quoting verbatim part of an article in “Chemproject” on the Web, which explains clearly the implications of the foregoing sentence. “Matter/antimatter reactions would heat a tungsten core which  heats hydrogen as it flows through and then out of a rocket nozzle. This design is actually based on the solid core fission reactor, in which nuclear reactions are used to heat water and make something that is in effect an extremely efficient steam engine. This plan would provide an impulse of 800-1000 seconds more than twice that of the space shuttle. “  The article goes on to say that there are plans for a 400 ton spacecraft that could travel to Mars and back in four months, using only a few billionths of a gram of antimatter. This, it points out, is clearly much more efficient than current chemical propulsion , removing the need for large propellant tanks. Unfortunately, the price of antimatter as a propellant is prohibitive. At present, one milligram of antimatter costs  nearly one hundred billion dollars to produce.

All in all, space exploration is a possibility – in the future! Much more research has to be done of course  and the physical laws might change again leaving mankind with a breakthrough – or a dead end! It will however depend (as far as we can see) on the use of antimatter (as a propellant). Space travel is not at present a necessity but one day it will be. One forecast is that in the future,  antimatter from comets will  be used by the human race for deep space travel. Wind and solar dust are blasting antimatter off comets This can  be (or will be ) collected in Penning Traps. At least , this is the plan. As the “Antimatter Energy” article (on the Web) says, using antimatter as a source of energy will enable millions of people in spacecraft to travel to space stations orbiting the Earth in  minutes.  A telling comment: “A metric ton of antimatter could supply the  world`s energy needs for a year”. A real benefit apart from the obvious, is “taking billions out of poverty.”  One day the space and resources on this planet will be exhausted. Will we have the ability to travel to distant planets to meet our future needs? It is a question that demands a positive answer.          

© A.B. Finlay Ph.D