The End of the World and the LHC

Before last Christmas the European Organisation for Nuclear Research (CERN) recommissioned their Large Hadron Collider (LHC) particle machine with great success allowing it to collide atomic particles at the highest energies ever achieved in a laboratory. It was then shut down to allow for the winter period.

It has now started up again (Sunday 28th Feb) and the first beams of 2010 have been circulated in each direction. Over the next few weeks, the machine will be ramped up to about half it's design energy and then allowed to run for about 18 months. Then it will be shut down to allow extra work to prepare for bringing it up to it's full design energy.

This delay to full energy, while disappointing, is necessary for various technical reasons. It will mean the LHC will be competitive with the other big accelerator at Fermilab in America. Therefore in my opinion the LHC is unlikely to deliver any exciting new physics while running at this energy level.

So, those who believe that the machine, when running at it's full design energy, will create a black hole which will end the world can breathe a sign of relief.

What is the LHC? Basically it is an underground circular pipe approximately 27 kilometres in circumference through which protons (a member of a family of particles called hadrons) are accelerated and smashed together at four different points where the two rings of the machine intersect. These points are crammed with detection gear to measure the results of the collisions. Two protons smashing together at these incredible energies can produce a huge amount of other particles and the analysis of these collisions help scientists to build their theories of the fundamental nature of matter and the universe.

Machines like the LHC have helped build the theory called the standard model which is a description of how our world is put together at a fundamental level. It shows that there are four forces in our universe: two familiar: electromagnetism and gravity and two not so familiar: the strong and weak nuclear force. According to this model, quarks are the building blocks of matter and forces act through carrier particles exchanged between the particles of matter.

However, there are some things in our universe which the standard model can't explain. One of these is the vexing question as to why we need two very different theories to explain the very small and the very large. Quantum mechanics explains the very small (atoms etc and is the standard model mentioned above) while Einstein's general theory of relativity explains the very large. It has long been assumed that one theory should explain everything, yet these two theories cannot be reconciled. A theory which tries to do so is called String theory, the only problem being that there is not one iota of evidence for it. A beautiful theory with no shred of proof. This is one area the high energies of the LHC may be able to throw some light on.

Another problem is dark energy. Since the creation of our universe (the big bang) which happened about 14 billion years ago the universe around us has been expanding. Naturally you would think the expansion rate would begin to slow as the force of the big bang began to be resisted by gravity. However, a number of years ago this idea was shattered by the discovery that the universe was actually speeding up. So something must be creating an outward force and this was called dark energy. We have no idea what this dark energy might be so this is another area which the LHC will be examining.

How do particles have mass? What gives different particles different amounts of mass which react in different ways to the different forces? One answer is a particle called the Higgs particle (named after a physicist called Peter Higgs). This is a particle we definitely expect to find with the LHC. Of course not finding it means our standard model is wrong and will have to be looked at again. So even if we don't find what we expect, this will be fascinating in it's own right.

When we measure the amount of mass in our universe we find that the matter that we can see (stars, galaxies etc) only comes to a small percent of the total. About a quarter is some other sort of matter which we can't see called, appropriately, dark matter (different to dark energy). Will the LHC elucidate this problem?

Some other questions remain. Why is there more matter in the universe than antimatter? Are there more than 4 dimensions (three of space, one of time) in our universe? String theory for example exists in 11 dimensions (depending on the version of the theory). And of course, as these questions get answered, you can be sure they will give rise to lots more questions, some of which we haven't even thought of.

Now, let's get back to those who tried to stop the LHC being switched on because they said that the energies of this machine are so great they will give rise to a black hole which will destroy our planet in seconds. I like to refer to them as "end of the world" guys because they are just another in a long line of doomsday prophets who have been with us throughout history.

If you read the gospels you will find that Jesus himself fully expected the world to end if not within his own lifetime, then shortly thereafter. After all he did say "there are some here who will not die before they see the kingdom of God coming with power" (Mark 9:1). Of course some say that this is a literal interpretation and Jesus didn't mean that at all. Whatever the case, St Paul among many other disciples certainly seemed to believe that the end of the world was nigh.

There are tens if not hundreds of different predictions of the end of the world since New Testament times. For example around 1000 AD, there were many who were convinced that the Antichrist was about to arrive and usher in the end of days. The black plague of 1346 seemed to many to signal the last days. Just google end of world predictions to find many of these prophecies.

And in our own time we are all awaiting December 2012. Interestingly this is beginning to tie in nicely with the LHC black hole producer. As this machine will only run on half energy for the next 18 months, this brings us up to September 2011. Only 15 months or so to go till December 2012. So the machine may run longer on half energy and then be shut down for a little longer than expected. So it starts up again at full energy in December 2012 in good time to agree with the Mayan calendar prediction of the end of the world.

However, just as all the other predictions of the end of the world were wrong, I have no doubt that not only is the 2012 prediction a load of cobblers, but the possibility that the LHC will produce a black hole to swallow us all up is also wrong.

And in case you are worried, the energies of some cosmic rays striking our atmosphere every day have been measured as way in excess of anything the LHC could generate. And they haven't produced any black holes. Yet!