What’s the matter with Antimatter?

Physicists have been talking very excitedly recently about something that has been picked up by the satellite originally launched to study high-energy particles from the Sun.  The ‘Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics’, also known by the much friendlier acronym Pamela, has detected a belt of antimatter around the Earth.

The reason that Physicists are so excited by this is that, until now, suggestions that antimatter could be trapped in Earth’s magnetic field have been mainly theoretical.

So where did all this talk of antimatter start and what’s it all about?

Paul Dirac was a very shy but very clever physicist based in Bristol, England.  In 1933 he was awarded the Nobel Prize for being able to prove the existence of the positron by a method that has since become known as the ‘Dirac Equation’.  He was such a private individual that it took some persuasion to get him to accept his Nobel Prize. 

What Paul Dirac had been able to prove was that electrons had a ‘twin’ particle.. sort of like a mirror image.  Think of it like this: you’ve rolled out some cookie dough and are about to make some star shaped cookies.  You carefully push in your star-shaped cookie cutter into the dough and then gently remove it to create a star-shaped cookie.  Look again.  You made two star shapes: the star made out of cookie dough and the star-shaped hole in the rolled out dough.  Whilst it may just be a hole to you and me, to a scientist like Paul Dirac the star-hole is the cookie-star’s ‘twin’.  When Albert Einstein said that matter was just tightly packed energy particles he basically outlined the idea that energy is the cookie dough of nature.

If you continue with this train of thought then every particle in the universe must also have it’s twin .. an antiparticle! 

Perhaps you’re thinking that this is all rather far-fetched?  However, hospitals already use PET scans as a medical diagnostic tool (PET stands for Positron Emission Tomography).  Scientists hope that one day it might be possible to use antiprotons for tumor irradiation.

StarshipEnterprise In science fiction spacecraft like the Star-ship Enterprise in Star Trek, antimatter is used as a source of fuel to propel spaceships ‘to boldly go where no man has gone before'.  When antimatter comes into contact with matter they annihilate one another but in the process create a blinding flash of pure energy.  The problem is that you’d need an awful lot of antimatter to be able to generate sufficient energy to power your car much less a space craft.

Hang on a minute, I hear you cry!  You said that if antimatter comes into contact with matter they annihilate one another… well, if that’s the case why hasn’t all that antimatter come crashing into earth and finished us off?  The answer is simple: it’s the Earth’s magnetic field that is keeping the two separate.  Rather like when you put two magnets end to end and one ‘forces’ the other away

With such an abundant supply of antimatter now detected within the Earth’s magnetic field, physicists are rethinking what they might be able to do with it.

Now perhaps you’re beginning to see why scientists are so excited about Pamela’s discovery. 


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