Ignas interviewed Christoph again - this time on camera - in his office at CERN during Open Days in September, 2019.

Christoph, first of all, how would you introduce yourself?

Well, I’m a physicist. I’ve studied in Aachen and came to CERN for my diploma thesis, later my Ph.D. thesis. In the end, I became a fellow and finally a staff person. And I’m here at CERN already for 25 years.

What is your responsibility now?

I’m an advisor in the international relations group for European and Central Asian countries, which are not yet full members.

Great. Could you please describe the mission of CERN?

Well, actually, we have four missions. So, the first mission, of course, is fundamental research. We want to understand the Big Bang, we want to understand the fundamental particles and how these particles interact with each other.

But to do fundamental research, you need experiments, you need accelerators, you need apparatuses. And so, you cannot buy them off the shelf. You have to build them. We do both fundamental research and applied sciences.

On top of that, we have the mission to educate people, transfer knowledge. A lot of people come to CERN. We have roughly 13,000 guest scientists coming to CERN, and they get trained to our installation, to our knowledge, and they stay here for weeks, months, years. But at a specific moment, they go back to their country, and that’s what we call knowledge transfer.

And last but not least, uniting people from different cultures, different mentalities to work here, because our original model in ’54 was “science for peace”. And that is very important. Everything we do at CERN is peaceful.

In our convention, it’s clearly mapped; we have nothing to do with military research and so ever. Everything we do has to be published. So, no secret research — everything is published.

And you are here at CERN with a cameraman. Wherever you go, you can take photos, and there’s no restriction. That’s the way we ensure that it’s really transparent and open.

And the whole origin of CERN presumes some political background of it.

Yes. CERN was founded in ’54 by 12 European member states. Actually, it was in ’49 when a philosopher and a French physicist came with a proposal after the experience of Nagasaki, Hiroshima, with a purpose to make nuclear science and research peaceful. Another American physicist Isidor Rabi supported them, later UNESCO took it over, and today UNESCO is the custodian of our convention.

If we come back to physics, what could be your objective in terms of science?

Well, in physics, what we do at CERN is accelerator-based particle physics. We accelerate the particles, we smash these particles together, and then we analyze what comes out of this collision. And what we do by doing these collisions, we recreate the conditions just after Big Bang.

We build a time machine, so to say — we go back 13.5 billion years in time. So, we are just a split second after the Big Bang. And we create this condition, and we see how the universe was at that very moment.

Let’s say we’re in a closed house, and we just open some windows, and with the accelerator, which is bigger, better, we can open more windows and look even deeper in the structure of matter. And of course, we have a theory how this matter works. We probe the theory, and each time the theory prevails. We can measure the prediction of the theory.

The last big success of the theory was in 2012, where we discovered the last missing plausible of the theory, the .

We had our standard model of particle physics, and this standard model was developed 60 years ago. And this model is probed and probed and probed. And each time, the result was inconsistent with the theory, which is excellent.

And in 2012, we discovered the last particle which was predicted by this theory, the Higgs boson, and only one year later, the two physicists who predicted and developed the theory for this Higgs particle were awarded the Nobel Prize.

However, we know that this theory isn’t predicting everything. Actually, the theory only predicts or describes 5% of our universe. Ninety-five percent is not covered by the theory. What does it mean?

That means we have particles or metal, which we do not know. We know it should exist. We can look at the galaxies, how galaxies spin around, and then we can make estimations of how much mass should be in a galaxy. When we see how the galaxy’s rotating, there’s a discrepancy. It looks like there’s not enough mass in the galaxy.

How do we know the mass? We count the stars. Then, we know how heavy a star is, and so we have a rough idea of how much mass should be in the galaxy. But if we count all the stars in the galaxy, we find out that there’s still not enough mass to explain how the galaxies rotate.

Therefore, there should be more matter — but we don’t see that matter. We call it . Scientists have no clue what it is. But it’s not a normal matter — it’s a special matter. How this matter interacts with us, we don’t know. So, this is something we have to understand. And we have to look for this dark matter.

Now, we know how much dark matter there is because we know how much matter is in the galaxy to make the rotation. But there’s another problem — we add all the galaxies together, including the dark matter, but massive particles, gravitation, they tend to go together. However, the universe is expanding. So, it’s unusual. We have an expanding universe, but from the amount of matter of gravity, it should actually shrink.

We have to postulate not only dark matter to understand how galaxies rotate, but we have to assume dark energy, which makes the energy expanding. And 95% of what we have in the universe is either dark matter or dark energy, and only 5% is an ordinary matter like this table or myself.

So, you see, there are plenty of things we don’t know.

Amazing. Are dark matter & dark energy distributed evenly throughout the universe?

Well, of course, we assume that there’s no reason why on large scale things should be non-homogeneous. We don’t know — we assume, and of course, the dark matter, the dark energy, the normal matter is distributed evenly. We have to discover this assumption before we can prove it. And we hope, for instance, with this LHC accelerator to be able to produce matter, which could explain or give a hint of what dark matter is. But right now we haven’t found it yet.

I guess very few people acknowledge this. How does it feel about dealing with 5% of things you understand, knowing that 95% around is unclear?

That is a very good question. But it’s always in the history of our society starting from the Stone Age, our knowledge is always increasing. There are so many things we do not know. So, I think we shouldn’t be scared of what we don’t know. We should take it as a chance to say, okay, there’s something which you don’t know. Let’s go for it.

Like Columbus, when he was just sailing, people said, look, the earth is flat. And when you sail, you will fall off the earth. And he said, “Still, I want to go to the end, I want to understand.”

Most of society is always scared, but we need these people who are not afraid. We need these brave people who just go one step beyond. That’s the reason why it’s so fantastic to work at CERN because we are one of those who always try to go one step beyond.

But again, the ratio is enormous: 5 to 95.


So, do you have a feeling that you’re at least moving to gain 6% of…

I’m afraid, no, because it’s not that we know from 5%, 6%, 7%. Unfortunately, that’s not like that. Either you go from 5%, then immediately do the rest once you have discovered it.

But we all still operate and live with the knowledge or at least hope that we know and understand that 5% of the universe around us.

Yes, but most people don’t know it’s only 5% [Laughs].

How reliable can we be operating within the range of that 5 % we know?

Good question. Then we have to talk about interaction. Actually, to our current knowledge, there are only four forces, how particles interact. The most known force is gravitation. Then we have a magnetic force.

Also, we know that the other two forces, which are unknown. It’s a strong force that keeps the nucleus together. In the atom, you have the nucleus, and the electron is spinning around.

The nucleus consists of protons and neutrons. Neutrons are neutral. Protons have a positive charge. And you have plenty of positive charges. And in principle, it should just expand. But it stays together.

So, there must be a force that is stronger there than the electromagnetic force to keep things together.

And there is a fourth force, the weak force, which sometimes makes nuclear decay.

Now, you would say, “I can feel gravitation, I cannot feel a strong force, I can feel gravitation only.” Yes, you can because compared to the electromagnetic force, you’ve plus and minus. And there is a strong force between them, but everything we touch here is neutral. Everything is only one charge. You don’t have an anti charge. So, everything adds up. Thus, the resulting force is significant, it’s tangible, but on the particle level, it’s minus. Very, very minuscule.

So, just you have this iPhone here. This iPhone weighs, let’s say 100 grams. What does it take to make this iPhone? You have to accommodate as many atoms just to create a force, which makes this small piece of only 100 grams. So, we can see how small this force is.

This force is very weak. Even if 95%, it’s there — it could be everywhere here. It could be thick of dark matter that doesn’t interact with us.

So, if you cannot see it, you can’t feel it. But it could be here anywhere. This room could be full of dark matter. Actually, 95% of this table could be complete, but you can’t interact.

But there could be some other force.

Yes. Absolutely, that could be. Fantasy is the limit. Of course, we can imagine more forces, more other things. And we have plenty of theorists, who then develop new theorie. A theory is only a good theory if there are means to prove it.

When it comes to experimenting, you get quite isolated space or conditions to achieve what you want. You presume there is no interference from dark matter or dark energy in the universe. Aren’t you bothered by any of those?

Yes, and no. We produce particles that we know when we do the collision. And we have this Higgs boson, which we discovered in 2012. We know that the Higgs boson couples to mass. It could be that this Higgs boson couples to the dark matter. But the coupling is minimal.

Our goal is to produce even more collisions, more events, more information, more data. We are going to find some reactions where the Higgs boson couples to this dark matter. Again, so far, we haven’t found it. But our LHC program will last until 2037. We still have plenty of time to link more data. That is how we think we could find dark matter. We are coupling, and we have the Higgs boson.

Since the process of coupling is very weak and rare, it’s like finding a needle in a haystack. We have to have a massive amount of data. So, we need to increase the amount of data to be able to find very rare events. When you flip a coin — it has two sides. But there’s a third possibility that the coin may stop on the edge.

Unlikely, but...

Very unlikely. How often do you have to flip a coin that it stops on the edge? Many times. The process exists, but we need to collect a lot of statistics to find reasons.

Everything is speculation because of theory. We assume that because the Higgs boson couples interact with dark matter — we are pursuing the dark matter. We need a lot of data to find this very rare process where the Higgs boson couples with dark matter.

Imagine you have a theory about how this iPhone works. You give this iPhone to a theorist. A theorist will come back with a theory that will be most likely wrong. The next theorist will come with another theory. So, we have plenty of theories. We do an experiment, and we take two iPhones, we collide them, clash them, and then we see all the particles, the debris everywhere. And then we ask a theorist to evaluate.

At a particular moment, we will find out that the debris is identical to our primary measurement. And then we will think that we understood how the iPhone works. However, there’s no proof at all.

So, in this picture, where does the coupling of the Higgs boson with a dark matter would be put?

In that picture, it would be just some different chips how they are glued, if they’re firmly glued or just welded, soldered, and so on. It’s how they are built inside.

Yeah. So, basically, you expect to discover both chips or both parts. And the randomness of discovery comes from the complexity of a collision.

Yes, exactly. You have a lot of processes. Like a dice has six possibilities. Of course, there might be very rare processes that we don’t even expect but they exist. They’re so rare that we have to roll the dice quite often to finally get this process.

How much predetermination is there?

Well, quantum physics postulates that there is no predetermination. There’s always a particular element of randomness. What does it mean? There’s still a certain amount of uncertainty. Let’s take an example of . In this experiment, you have a cat in a box. Is the cat alive or dead?

And actually, before you look inside, the cat is in a strange state between death and living. And only when you open the box, then you probe the system — the cat becomes either alive or dead. It’s the same on a particle level, the particles are in an undefined state.

For instance, the electron is not spinning at all. It has a probability to be here or elsewhere. But when you do an experiment, then you will see the electron is in a unique position. But if you don’t look at it, it could be anywhere.

Therefore, the probing will force the system in one or the other state. And that’s randomness. We cannot predict it. It could be here, it could be there. But we can only say if you do it millions of times, most of the time it’s there and rarely elsewhere. It will have a statistical significance. But for any particular event, it’s not possible.

Again, with the dice, you know if I roll, and by one out six, I should get a five. But if I do it only once, which number I get? I don’t know. It’s impossible to predict. But if I do it 1,000 times or 6,000 times, then roughly 1,000 times I should get a five. It could be 990, 1,010. But it shouldn’t be 1.

So, we cannot make a prediction on the individual collision, on the particular event. We can only collect a lot of data and guess using statistics. However this is completely random on a one-to-one level. It’s not predictable.

There was a lovely anecdote from a famous French astronomer 300 years ago. He looked at the skies. He said, “Give me the position of all the stars at one single moment and then I can calculate how it worked in the past, how it will work in the present, in the future.” A very predictive model of our universe. Then quantum physics came and brought randomness, unpredictability, uncertainty. Everything has changed completely. Now, we only talk about probabilities. I hope that was answering your question.

Absolutely. How does it transform into your life?

It has an impact on my professional life because I’m a physicist. I think like a physicist, you have a different approach to probability.

When we talk about risks, people have an extraordinary precision of risks. They do things that are very risky and have no problem with it. But they fear things that are not risky at all. For instance, people are afraid to fly planes. But the probability of the crashing is minimal. Whereas they don’t fear driving the bicycle.

At a certain moment, I think we have to be more conscious about the risks and the probabilities and to have a better understanding of probabilities. Because of quantum physics I have a different view on probabilistic and statistics.

Fantastic. So, how does it feel to be unpredictable on a fundamental level?

Well, we know the probabilities. The randomness in the sense of predicting a single random event. But of course, we have a pretty good understanding of how the process works. It’s like a dice — if I roll the dice, I will not know which number comes up.

Yeah, correct. Let’s come back to the fundamentals. How could statistics help predict the position of a particle?

Albert Einstein was contributing to quantum physics. He was talking about the concept of uncertainty until his death.

Albert Einstein famously said, “God doesn’t play dice.” He couldn’t believe that this is fundamental. And indeed, from our inner core this uncertainty, it’s so nice. We want to have it more tangible.

And particle physics is now a hundred years old. So far, quantum physics prevailed. And we don’t have a predictable theory. I don’t say it will not come. Who knows? But today, we have to believe that there is uncertainty.

For instance, you can not measure the velocity of a driving car, and at the same time, where the car is. Either you measure the velocity very precisely, but then you’re uncertain where it is.

Beautiful. How does it affect your sense of freedom?

I believe that there is no free will. Why? Because I think we are very complex biological machinery and we are influenced by so many parameters and things, that I think free will doesn’t exist.

Our decision process is influenced by many outside parameters. I’m interacting with you. I’m interacting with matter. I’m interacting with everything. A change occurs by interacting. Therefore, I think free will doesn’t exist. That doesn’t mean everything is random either.

Thank you. This was an excellent explanation. And, anyway, we are destined to act in human bodies and perform our missions. So, does this sort of position affect your daily life?

Absolutely. For instance, I’m a physicist at CERN. Why am I a physicist? Why am I at CERN?

Why am I at CERN, I can tell you because of a dice. Why? Because when I studied physics, I had to do my diploma exam, and I could choose a professor who examines you. So, I’ve selected a professor, but a lot of students have chosen the same professor. Almost every other student had chosen the same professor. So, they had to roll the dice to find out who will be examined by another professor.

At the end, I was chosen to be examined by another professor. My professor sent me to CERN. And all my life has changed because of the dice.

There could be so many different paths. It is unpredictable where I will end up in 10 years, but I know there is always a way — so I have a vision. The vision could have changed any moment by choosing a different path.

Understanding this makes me quite open to new opportunities. Anyway, I’m here because of just pure luck.

Was it an actual dice play, or is it just a metaphor?

It was not an actual dice play. It was too complicated. They just put the names on a paper, and then they pulled the paper out of the hat. So, it was really random.

Yeah, and it affected your life tremendously.

I’m sure I would have a great life if I was not in CERN. I would be equally happy right now.

What makes you so sure?

There isn’t only one path that makes you happy. It would be too complicated. Wherever I go, I would end up happy. That’s my inner belief because I have to make the best out of the different possibilities.

How much happiness do you obtain from a family?

A lot. The family is the core, and it always grounds me. Having kids, it’s fantastic because of responsibility. One just can’t imagine how much work and responsibility you have with a kid. But also the pleasure you get out of a kid. You are “the” person for the kid. You are irreplaceable.

There is a saying that everybody is replaceable. There’s one exception — you are not replaceable if you’re loved. And that is what makes the difference. The family is essential.

You wouldn’t have these particular kids without your specific wife.


How did you manage to get this particular woman into your life?

We met at CERN. And I remember the very first moment when I met her, when I saw her we were helping out some friends to move. She came in a tiny car. And she’s a tall lady. [Laughs] Since she moved out of this tiny car, I saw her. I don’t know what happened, but it was “her”. And everything else worked out. We met by complete coincidence because of common friends.

Yeah, this is very romantic, and Christine will join us later in the evening.

Yes, yes.

What sort of coincidences led to a situation when you experienced the moment of “wow”?

Yeah, first of all, to get us together to the same place at the same time. It’s a lot of improbable events that had to happen to make this event happen. Again, the probability that I would have met her it’s almost zero. But it happened. Some things will happen at a particular moment, even if it’s improbable — yet the unlikely will happen.

So, I was asked to help out. And Christine was asked to help out too. That’s how we met.

Well, if we focus now on you as a personality, how do your decisions develop in this world? Can you elaborate more about free will?

Well, when I say there’s no free will, I meant in extra terms. Of course, I’m the result of my chemistry; I’m the result of my genes, which by the way, also change in the course of life. I am the result of my experience, I’m the result of my surroundings.

Making a conscious decision, which makes you happy in the long run, has to be a decision not only in favor of something but against something — there are always two doors, left or right. I can choose the right door, but at the same moment, I’ve chosen not to take the left door.

Later you go back and ask yourself, “Why did I make this decision?” And at that moment, there were reasons that were valid and authentic and reasonable.

I made a decision to my best knowledge. Therefore, I never regret my decision.

Nowadays, society has more and more options. Look, in the Middle Ages, you just chose a profession of your father. There was no question about it, and people were equally happy.

But nowadays you have so many options. Because of the fear of not taking the right opportunity, you don’t have any options. Then a stagnation happens because of your fear — you don’t move at all.

What has changed for 100 years in this respect?

Well, life was local. People didn’t travel — they didn’t know about other possibilities. Maybe once a year they went to the market in the biggest village. The radius of their activity was maybe 10, 20 kilometers.

So, I think we have far too many options. And it’s not possible to go back.

And you gave an excellent example of the difference between being replaceable and irreplaceable. Is there much difference in making a decision to love?

A decision to love it’s not a conscious decision. Love is all about pure chemistry. Either it clicks, or it doesn’t click. Then, of course, there’s a decision to pursue it. It’s just the chemistry inside the brain or the hormones, which then produced and then docked on the right receptor and so on.

Alan Lightman described his way of making a proper decision. First, you need to have a prepared mind. Then a random event will occur, and then you will take a willful action.

So, what is this random event?

When you see a lady coming out of a tiny car…

Ah, yes, yeah. Decisions are triggered by interactions with the environment.

But you need to have a prepared mind, and you need to take a willful action afterward.

Yes. You have to be open. But I have doubts because what is willful? That is coming back to the free will. So…

Conscious, maybe.

Conscious action is better. When I saw my wife for the first time, and so, something clicked. So, it was not a willful action. It was just something else that happened.

I guess you made a move after that “click”.

Yes, yes.

That was a willful action.

True. It was triggered by will or chemistry in my brain. These things are so interleaved. You have a permanent stimulus around yourself. And conscious decision it’s rare. It’s very rare if it exists at all.

But I don’t say everything is random and you should not think about things. It’s something different. Okay?

I like your approach. This is quite a brave statement - that conscious decisions are very rare.


Conscious decision arises from very small conscious thought. We focus on conscious decisions, and we make an assumption that they are quite rare.


When a conscious decision happens, that arises from a conscious thought, and a thought is “an event”.

Yes, yes, yes.

And if the event originated out of the fault, it could quickly go to a particle level. First you attract a level of ions or molecules. And then I presume that it requires a specific composition of particles for a conscious decision or a thought to happen.

Yes. Well, if you look at the brain, you have the synapses, and they connect, and then you have electrical current, and they trigger the stimulus. And the electrical current is just electrons and particles.

In the end, you’re right; it’s all about fundamental particle electrons, which today we believe are fundamental, but who knows. Fundamental particles travel and make the connection, and connection then create a complex environment in the brain. Something which is a thought. I absolutely believe that’s correct.

But where are these electrons coming from? I’ll give you one example. If I would be a powerful magnetic field, the electrons will deviate because they are charged particles. In the magnetic field, they deviate. So, they will not hit the synapses anymore — then things are different. So, I can be influenced by external parameters or this flux of particles. It’s very fragile.

But if we make a distinction between unconscious action and conscious thought, then it leads to a specific state of particle physics.

Yes, yes.

Then, it leads to a better understanding of how conscious decisions arise.

Maybe. I don’t have the answer if the human being is just a product of chemistry, physics, or is there something even more? But I’m aware of myself. This iPhone can do a lot of things. But is it self-conscious? No.

Would you agree that one objective of CERN would be to contribute to a better understanding of consciousness?

On the large scale, yes, definitely. We try to understand our world. A conscious decision is important and makes us hopeful. I think there is a long, long way to go. But let’s hope for it.

This is a nice moment to say thank you.

Thank you very much for the opportunity to discuss this with you. It’s a pleasure.