Home | Sitemap | Contact us
 
this site All CERN
At work on the Antiproton Decelerator

Angels and Demons

Dan Brown's book Angels and Demons is a detective story about a secret society that wants to destroy the Vatican using an antimatter bomb. In the book, the antimatter is stolen from CERN.

Angels and Demons ambigram

(ambigram courtesy John Langdon)

Readers have asked us even more questions about the technologies used in the story. Here are our answers.

Does CERN exist?

Well, yes, it does.  You can see us to the left and slightly up from the centre of the city of Meyrin.

Is it located in Switzerland?

Part is in Switzerland, part in France across the border.  CERN is not a Swiss institute, but an international organization. We are very close to Geneva's intercontinental airport.

What does the acronym CERN mean?

That is a long story.

Does it consist of red brick buildings with white-frocked scientists running around carrying files?

No, that is rather far from reality: we have mostly white buildings made of concrete and the scientists wear everyday clothes and they mostly do not carry files.

Was the web really invented at CERN as the book states?

Yes, indeed, the web came from CERN, invented here by Tim Berners-Lee in 1989.

Does antimatter exist?

Yes, it does, and we make it routinely at CERN. Antimatter was predicted by P.A.M. Dirac's theory of quantum mechanics in 1928 and antiparticles were found soon after by Carl Anderson. CERN is not the only research institute to produce and study antimatter.

How is antimatter contained?

With very great difficulty. It annihilates completely when it touches any normal matter. There are two cases:

Case 1: If an antiparticle is electrically neutral then electric and magnetic fields have no hold on it at all. Therefore, there is no easy way to contain neutral antimatter particles, i.e. no way to keep them away from the normal-matter walls of the vessel in which they are.  They therefore almost immediately come into contact with normal matter and annihilate.

Case 2: For electrically charged antimatter particles such as positrons (antielectrons) and antiprotons we know how to use "electromagnetic bottles" to contain them. However:  like charges repel each other.  So it is not possible to put a large quantity of antiprotons together because the repulsive forces between them soon become too strong for the fields that hold them away from the walls.  And you cannot put a mixture of positive antielectrons and negative antiprotons together, because they will make antihydrogen, which is neutral and we are in case 1 again.

So only very minute quantities can be contained.

What are the future uses of antimatter?

Antielectrons, or positrons, are already used in PET scanners in medicine (Positron-Emission Tomography = PET).

Other uses are in studying the laws of nature, as we do at CERN.  The team of the PS210 experiment at the Low Energy Antiproton Ring (LEAR) at CERN made the first antihydrogen atoms in 1995. Then, in 2002 experiments managed to produce tens of thousands of antihydrogen atoms, a sufficient number to study this gas in its antimatter form.  However, although ‘tens of thousands’ may sound a lot, it's really a very very small amount.  You would need 10 000 000 000 000 000 000 times that amount to have enough antihydrogen gas to fill a toy balloon!  If we could somehow store our daily production, it would take us 25 000 000 billion years to fill the balloon.  The universe has only been around for 13.7 billion years... So the Angels and Demons scenario is pure fiction.

Can we hope to use antimatter as a source of energy? Do you feel antimatter could power vehicles in the future, or would it just be used for major power sources?

There is no possibility to use antimatter as energy ‘source’.  Unlike solar energy, coal or oil, antimatter does not occur in nature:  we have to make every particle at the expense of much more energy than it can give back during annihilation.

You might imagine antimatter as a possible temporary storage medium for energy, much like you store electricity in rechargeable batteries.  The process of charging the battery is reversible with relatively small loss.  Still, it takes more energy to charge the battery than what you get back out of it.  For antimatter the loss factors are so enormous that it will never be practical.

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.

I was hoping antimatter would be the future answer to our energy needs. It seems more research is needed for this to happen.

No, the true answer is that it will never happen simply because of the entropy problem.  Creating antimatter out of energy via E=mc2 unfortunately always produces equal amounts of normal matter and antimatter. This is fundamentally built into the universe.  For any given amount E of energy you will get m/2 grams of antimatter and m/2 grams of matter.  Putting these two amounts back together and annihilating them gives back E.  But the process is not without loss:  today the loss is enormous, but even if we could make the process very efficient, we would still not have any net gain!

It is not a matter of "more research" or "more advanced technology" to find ways around these limitations. Antimatter is a fundamental state of matter.  It could only become a source of energy if you happened to find a large amount of antimatter lying around somewhere (e.g. in a distant galaxy), in the same way we find oil and oxygen lying around on Earth.  But as far as we can see (billions of light years), the universe is entirely made of normal matter and antimatter has to be painstakingly created.

This by the way shows that the symmetry between matter and antimatter as stated above does not hold at very high energies, such as shortly after the Big Bang, since otherwise there should be as much matter as antimatter in the Universe. These energies are higher than any that can be achieved on Earth at present; what future research might tell us is how this asymmetry came about, although it is extremely unlikely to lead to the possibility of using antimatter as an energy source.

Can we make antimatter bombs?

There is no possibility to make antimatter bombs for the same reason you cannot use it to store energy: we can't accumulate enough of it at high enough density.

Sociological note:  scientists realised that the atom bomb was a real possibility many years before one was actually built and exploded, and then the public was totally surprised and amazed.  The antimatter bomb on the other hand has been imagined by the public who wants to know more about it, yet we have known for a very long time that it's not at all a practical device...

Why has antimatter received no media attention?

It has received a lot of media attention, though usually in the scientific press.  Also, antimatter is not ‘new’:  we’ve been using it for decades; antimatter has been observed for almost a hundred years.

Is antimatter truly 100% efficient?

Depends what you mean by efficient.  If you start from two equal quantities m/2 of matter and m/2 of antimatter, then you get exactly E=mc2 as energy out.  Of course.  It converts at 100%.

But that is not the point:  how much effort do you have to put in to get m/2 grams of antimatter?  Well, theoretically E=mc2 because half of the energy will become normal matter.  So you gain nothing.  But the process of creating antimatter is highly inefficient:  when you make antimatter particles, a lot of them go astray before you can catch them.  Everything happens at nearly the speed of light, and the particles created zoom off in all directions.  Somewhat like cooking food over a campfire:  most of the heat is lost and does not go into the cooking of the food, it disappears as radiation into the dark night sky. Very inefficient.

In fact we have to use hundreds of times more energy to create the matter/antimatter pairs than the theoretical minimum of mc2, but we won't ever get back more than mc2.

Do you make antimatter as described in the book?

No. The production and storage of antimatter at CERN is not at all as decribed in the book:  you cannot stand next to the Large Hadron Collider (LHC) and see it come out, especially since the LHC accelerator is not yet in operation.  To make antiprotons we collide protons with a block of tungsten (Wolfram).  Out of this come a large number of particles, some of which are antiprotons.  Only the antiprotons are useful, and only those that fly out in the right direction. So that's where your energy loss goes:  it is like trying to water a pot of flowers but you only have a sprinkler that sprays over the whole garden.  Of course, we constantly apply new tricks to become more efficient at collecting antiparticles, but at the level of elementary particles this is extremely difficult and sometimes impossible.

Why then do you build the LHC?

The reason for building the LHC accelerator is not to make antimatter but to produce concentrations of energy high enough to study effects that will help us understand some of the remaining questions in physics.  We say concentrations, because we are not talking about huge amounts of energy but enormous concentration.  The energy in each particle that we will accelerate in the LHC is equivalent to the amount of energy in a flying mosquito.  Not much at all in absolute terms, but it will be concentrated in a very minute space and inside that minute space things will resemble the state of the universe close to the Big Bang.

You should compare the concentration effect to what people can learn about the quality of a wooden floor by walking over it.  If a large man wearing normal shoes and a petite woman wearing sharp stiletto heels walk over the same floor, the man will not make dents, but the woman, despite her lower weight, may leave marks:  the pressure created at the stiletto heels is far higher.  So that's like what the LHC will do:  concentrate little energy into a very minute space to make a huge concentration effect and learn something about the Big Bang.

Does CERN have a particle accelerator 27 miles long?

The LHC accelerator is a ring of 27 kilometers in circumference. The LHC is in a tunnel about 100 m underground. You can see the round outline of it marked on a map of the area.

In fact, why do you make antimatter at CERN?

The principal reason is to study the laws of Nature. The current physics theories predict a number of effects, and many of the effects concern antimatter. If experiments do not observe the predictions, then the theory is not accurate and needs to be amended or reworked. This is how science progresses.

Another reason is to get extremely high energy densities in collisions of matter and antimatter particles, since they annihilate completely when they meet.  From this annihilation energy other interesting particles may be created (this was mainly how the Large Electron Positron collider operated).

How is energy extracted from antimatter?

When a normal matter particle hits an antimatter particle, they mutually annihilate into a very concentrated burst of pure energy, from which in turn particles are created.  These new particles can be matter particles or energy particles (photons), depending on a number of factors, with an obvious constraint that the total incoming energy is exactly equal to the outgoing energy.  Almost all of it ends up as heat.  Not very useful.

How safe is antimatter?

Perfectly safe, given the minute quantities we can make.  It would be very dangerous if we could make a few grams of it, but we can't.

If so, does CERN have protocols to keep the public safe?

There is no danger from antimatter. There are of course other dangers on the CERN site, as in any laboratory:  high voltage power in certain areas, deep pits to fall in, etc. but for these dangers the usual industrial safety measures are of course put in place.  There is no radioactive leak danger for the public as you might find around nuclear power stations.  There is even no indirect danger such as from thermal power stations and oil consumption which produce longer term pollution and global warming.

Does one gram of antimatter contain the energy of a twenty kiloton nuclear bomb?

A "kiloton" in this context means a thousand tons of TNT explosive. Twenty kilotons was the equivalent of the atom bomb that destroyed Hiroshima.

The question is somewhat confusing:  you are probably talking about the explosive release of energy by the sudden annihilation of one gram of antimatter. Let's calculate it.  A "kiloton of TNT" is not a metric unit, it corresponds to 4.2x1012 joules.  A 60 watt light bulb consumes 60 joules of energy per second.  The notation 1012 means a 1 followed by 12 zeros:

1'000 = kilo = 103    1'000'000 = mega = 106    1'000'000'000 = giga = 109    1'000'000'000'000 = tera = 1012

So a kiloton is 4.2 terajoules or 4.2 TJ.

A gram is 0.001 kg.  The speed of light is 300'000 km/s or 300'000'000 meter/s.  Now E=mc2 so for 1 gram we get

E= 0.001 x 300'000'000 x 300'000'000 kgm2/s2 = 90'000'000'000'000 J or 9x1013 joules or 90x1012 J or 90 TJ.

If 4.2 TJ corresponds to a kiloton of TNT, then 90 TJ corresponds to 90/4.2 = 21.4 kiloton. About right.

But for the antimatter bomb we are actually talking about two grams: one gram of antimatter, annihilating with one gram of normal matter, and therefore you would release twice that amount! You need only half a gram of antimatter to be equally destructive as the Hiroshima bomb, the half gram of normal matter is easy enough to find.

At CERN we make quantities of the order of 107 antiprotons per second and there are 6x1023 of them in a single gram of antihydrogen. You can easily calculate how long we would have to work to get one gram if we could make the 107 antiparticles every second:  we would need 6x10(23–7)=6x1016 seconds.  There are only 365x24x60x60 = 3x107 seconds in a year, so it would roughly take 6x1016/3x107 = 2x109 or about two billion years!  Of course, it would be utterly impossible to contain this amount of pure negative electric charge.

Did CERN scientists actually invent the internet?

No. The internet was originally based on work done by Louis Pouzin in France, taken up by Vint Cerf and Bob Kahn in the US in the 1970's. The web however was invented and developed entirely by Tim Berners-Lee and a small team at CERN during 1989-1994. The story of the Internet and the Web can be read in "How the Web was born". Perhaps not as sexy as Angels and Demons, but everything in "How the Web was born" was first-hand testimony and research.

Does CERN own an X-33 spaceplane?

No.

October 2004
Last revised: November 2007

Related links