The Search for Sub-Atomic Beauty
Chris - Now we've heard from Ben Allanach about some of these collisions and the huge energy that are going to be produced. Presumably from those collisions there are particles produced or evidence that particles get produced so we can try and understand what's inside atoms. What are you actually looking for in your experiments?
Cristina - That's right, we try to collide two protons together in this case, accelerated to about the speed of light. The fact that they have this huge energy will make it possible to produce heavy particles and particles that were never seen except at the very beginning of the universe. That's what we're trying to find, essentially new particles that we were not able to see before because we didn't have enough energy.
Chris - So what you're trying to do is to simulate, in a laboratory environment, the Big Bang?
Cristina - Kind of.
Chris - So you're turning a pinpoint of energy into the stuff, the matter that is the stuff we see around us today.
Cristina - Yes, that's quite the idea, yes.
Chris - I guess the question is though, is that safe? Are we going to spawn a new universe in CERN in Geneva where people do say it's the centre of the universe in some respects but is that a good idea?
Cristina - Yes it is actually, it's a very good idea and no, we are not creating an entire universe. Previously, for example in CERN, we have been smashing particles together for years. In fact, CERN has been celebrating its 50th year quite recently. Nothing of such catastrophe ever happened. There are reasons for that. The idea that we've got higher and higher energy is because we want somehow to go more and more back in time. We want to see the particles that were produced farther back in time. That doesn't mean that it's dangerous because these particles live so shortly and is not dangerous in itself that there will be no harm for anybody.
Chris - How can you really have faith that you've recreated what was going on at the Big Bang?
Cristina - Let's be honest, we will not create the exact condition of the Big Bang but what we want to do is to get a very similar condition as much as we can. That doesn't matter if it's not a perfect condition to try to understand how these particles were formed and the new particles that may come over and try to build more complete pictures from that.
Chris - So, theorising for a minute and straying into Ben's territory - what do you think actually happened then, when the universe was born? There was a lot of energy around then so can you just talk us through what you think, on paper at least, probably happened?
Cristina - Right, yes at the very beginning we think that there was a new state of matter which is called Plasma. This, in fact is one of the main topics of one of the experiments at LHC. You know that in quarks, quarks are confined in protons and neutrons so in fact we never see quarks free so far. We see protons and neutrons but not quarks. We believed at the very beginning there was such a hot and dense state of matter that the quarks were actually free. So it's all together some sort of big, hot and dense soup of quarks and gluons. From there the things started to freeze out and our model has to be somehow the kinds of studies that we do with gases and with liquid, that sort of thing. At some point somehow matter formed as atoms. Also light was released and went out forever. That is what we observed. From atoms we got bigger matter and so on.
Chris - So when you designed an experiment for the LHC as it will be, when it switches on next week in CERN, what's going to be happening is a stream of protons is gonna be whipping round this circle (27km long) at nearly the speed of light. Tremendously high energy and that beam will then be brought into collision course with a second beam going the other way. The two will then cannon into each other at a point, presumably you know where that collision will happen. So what are you looking for?
Cristina - At that point, in fact, there's going to be four places of collision along the ring. We place at these collision points some huge cameras. They take almost photographic pictures of what's going on. So from these pictures you try to use some sort of forensic science to go back and see from the traces that they left in the detector what was actually happening in the first collision.
Chris - That doesn't sound too complicated. The price tag is huge. How long are you going to have to do this for to see the kind of evidence that you need to know what's going on?
Cristina - Well, it depends what people are looking for. If you look for very rare processes, for things that you know are very, very rare you have to look for longer. There might be other things that you spot immediately. We hope to see the Higgs boson quite fast but, you know, you never know until you see it.
Chris - Ben mentioned it; you mentioned it. What is the Higgs boson?
Cristina - The Higgs boson is supposed to be the thing that gives everybody mass so we could imagine it's a sort of gelatine that fills the space. The bigger you are the bigger resistance this gelatine offers to you. So somehow the Higgs mass is this sort of gelatine that fills up the entire space. Somehow it gives you more mass because it gives you a measure of the resistance that you have going through it.
Chris - So this is what Ben tells us should exist?
Cristina - If it doesn't exist in fact, the whole theory needs to be revised quite fundamentally, yes.