AA-U1: Anti-matter

Introduction

In science fiction, antimatter is magical stuff. Used to power the Starship Enterprise and blow holes in space and time, it is to plot holes what Unibond is to broken walls, but does the reality of antimatter live up to the hype?

According to Princeton University’s WordNetWeb page antimatter is, “matter consisting of elementary particles that are antiparticles of those making up normal substances”.  However, according to Wikipedia, antimatter is, “A rock band formed by Duncan Patterson (former bassist of Anathema), and Nick Moss”.  For the sake of good science we will stick to the Princeton definition, they seem to know what’s what in the world of science.  Essentially, antimatter is matter that has opposite electrical charges in its constituent particles. For example, its electrons would be positive (positrons) and its protons negative (antiprotons).

History

Antimatter was first predicted in 1928 by a brilliant physicist named Paul Dirac. In the 1920s Erwin Schrödinger and Werner Heisenberg had finished work on the new Quantum Theory of physics. However their theory did not work for particles moving at relativistic speeds, that is, particles moving close to the speed of light. For the theory to work, it had to somehow conform to Einstein’s theory of Special Relativity. This is where Dirac got involved in the melee. In 1928 he developed equations that describe electrons moving at close to light speed. However, the solutions to his equations worked if the charges on the particles were positive or negative. Far from deducing that this was a mathematical trick, Dirac ran with the idea and theorised that every particle has an oppositely charged antiparticle. During his Nobel Prize acceptance speech in 1933, Dirac went as far as to speculate that there may be entire universes made up purely of antimatter. Later work by other theoretical physicists has revealed that most probably, matter and antimatter were created in equal amounts at the moment of the big bang. This concept is known as CP Symmetry. Although currently no mechanism is known to account for the lack of antimatter in the universe, it is thought that somehow CP Symmetry was violated and matter was created in slightly larger amounts.

Discovery

Dirac’s anti- electron was first discovered experimentally by Carl D Anderson in 1932 via shooting Gamma Rays into other materials to create electron – positron pairs. He won the Nobel Prize for his work in 1936.  The antiproton was discovered in 1955, during the early years of particle accelerators, by a team of scientists led by Emilio Serge. The same team discovered the antineutron one year later.  By 1965, boffins at CERN had succeeded in creating an anti-deuterium nucleus, confirming that antiparticles can come together to form atomic nuclei. It took nearly 35 years for scientists to sticky tape electrons onto the anti-nuclei, but the breakthrough came in 1995, once again via the brilliance of CERN. They managed to create 9 anti-atoms of hydrogen, a miniscule amount. Over time, the amounts and weights of atoms produced increased until 2002, where CERN managed to create 1000s of anti-atoms at a time. Still a small amount, but quite impressive.

In The World of Matter

The most incredible thing about antimatter however, is what happens when it touches normal matter… If a molecule of antimatter and a molecule of matter interact in space, they annihilate each other in a burst of pure energy. Just a single gram of antimatter is enough to create a weapon of devastating destructive capability. There is a reason antimatter is chosen to power fictional hyper drives and time machines, converting even a small object into pure energy without any losses, friction or inefficiencies gives you a massive amount of energy to play with. Don’t panic however, a spokesperson from CERN has been quoted as saying, “If we could assemble all the antimatter we've ever made at CERN and annihilate it with matter, we would have enough energy to light a single electric light bulb for a few minutes”.   Because of antimatters tendency to explode violently in your face, it is incredibly difficult to store. It would be like trying to store someone with bad allergies in a box made of peanuts and pollen, without them having a reaction.

CERN have come up with a method of suspending antimatter atoms in a vacuum using a magnetic field. The field holds the atoms in the vacuum, separating it from the walls of the container and the outside world. This method is only capable of storing several individual atoms at a time. Even if it were possible to store massive amounts of antimatter it probably would not be done. Any failure of containment would result in an immediate catastrophic annihilation. Could you sleep at night knowing the world could go up like a roman candle at the slightest provocation by a butter fingered scientist?

Other Examples of Antimatter

Asides form anti-hydrogen and individual antiparticles; anti-helium particles have been assembled in collider experiments.   Antimatter also exists naturally in space also but in very small quantities. The antimatter in our galaxy makes up less than 1/100 000 000th of its overall mass. Most of this is concentrated round a small cloud recently discovered near the centre of our galaxy. NASA have recently discovered that antimatter is created above clouds that cause thunder storms, this is the first time it has been observed terrestrially.

Antimatter has many future possibilities in the energy industry, in medicine, in spacecraft propulsion and more morbidly, as a weapon of mass destruction.

And remember, in the wise words of the brilliant Stephen Hawkins: if you ever meet your antiself in a bar, under no circumstances shake hands.

Bibliography and References

1) wordnetweb.princeton.edu/perl/webwn

2) http://livefromcern.web.cern.ch/livefromcern/antimatter/history/am-history00.html

3) http://en.wikipedia.org/wiki/Paul_Dirac#Personal_life

4) http://en.wikipedia.org/wiki/Antimatter

5) http://en.wikipedia.org/wiki/CP_violation

6) http://www.sciencedaily.com/releases/2009/03/090325132855.html) P. A. M. Dirac (1928). "The Quantum Theory of the Electron". Proceedings of the Royal Society of London: Series A 117 (778): 610–6246

7) http://nobelprize.org/nobel_prizes/physics/laureates/1936/anderson.html

8) http://livefromcern.web.cern.ch/livefromcern/antimatter/factory/AM-factory00.html

9) http://www.st-edmunds.cam.ac.uk/faraday/CIS/Gabrielse/lecture.htm

10) A Brief History of Time – Stephen HawkingA Brief History of Time - Stephen HawkingA Brief History of Time - Stephen Hawkingay/CIS/Gabrielse/lecture.htm
11) A Brief History of Time - Stephen Hawking