Rolf Tarrach: "The most powerful and best-functioning scientific theory is not understood by anyone."

Rolf Tarrach Siegel (Valencia, 1948) is a professor of quantum physics. He has served as president of the Spanish National Research Council (CSIC), rector of the University of Luxembourg, and president of the European University Association.

We have more and more information. Does that mean we have more knowledge?

— In English we talk about low-hanging fruit, the low-hanging fruit that's easier to harvest. This is what happens with knowledge: we've extracted the easy stuff, and extracting knowledge is becoming increasingly difficult. Furthermore, there's an increasing amount of low-quality information that's useless for extracting knowledge.

What is knowledge? When is it reliable?

— You should always ask yourself if knowledge depends on your characteristics. If I replicate it, will I find the same result?

Let's take an example.

— Two historians can have the same information about what happened to Charles I when he decided to wage war against the French, and you could write two different books. Because one is left-wing, the other right-wing, one doesn't like the French, etc. In economics, this happens all the time. You can take two Nobel Prize winners like Keynes and Hayek, and they won't agree on many things. Because economics or history have to do with social and human behavior and are so complicated that scientific methodologies aren't enough.

And this doesn't happen, for example, with physics?

— If Einstein hadn't formulated the special theory of relativity in 1905, someone else would have done it shortly after, and it would have been exactly the same. Because physics has nothing to do with human beings and, contrary to what people think, it's very easy.

But when we need it most, like with COVID or climate change, some people don't trust science.

— The problem is that in complex situations, even the best science needs some time to reach a consensus. When politics or society doesn't want to give you that time, you've already swallowed the spoils. And in science, we often talk about probabilities, and politicians want yes-or-no answers. If you talk to them about probabilities, they'll likely ask you to leave. And what science always does is provide solutions, as with climate change, which is really humanity's only major problem. The problem is that it gets mixed up with ideology. But there are things we know with absolute certainty.

Which is it?

— The first is that when the amount of CO₂ in the atmosphere increases, the temperature rises. Svante Arrhenius discovered this 130 years ago, and it took society 120 years to understand it.

If it took us 130 years to understand it, do we still have time to solve it?

— Climate change has some terrible characteristics. The first is that a CO₂ molecule stays in the atmosphere for an average of two hundred years. Now, strictly speaking, nothing is going to solve a problem for you for 100 or 150 or 200 or 250 years, and that demotivates everyone. Because evolution has made us perfect for solving immediate problems. We've done this very well, but solving a problem you'll never see... we're not prepared for that. And what's also certain is that we are jointly responsible for the increase in CO₂. This is true, even if some deny it.

How can artificial intelligence revolutionize everything?

— Nobody knows. Obviously, artificial intelligence lacks human characteristics, like a sense of humor. It doesn't have one, so it's also somewhat stupid. The thing is, AI has an immense capacity to extract information from the internet. It can take a thousand texts or so, average them out, and reproduce them for you. But currently, it's not really capable of doing extraordinary things. Well, with one exception. A company developed software to play a game, and the artificial intelligence learned to such an extent that the computer scientists themselves said they didn't understand how it worked because the system had acquired intuition.

Disturbing.

— Yes, very much so. Could it be dangerous? The truth is, no one knows. And why don't we know? Because we don't even know how consciousness emerged in us. So how can we know how artificial intelligence works? We still know very little about our own intelligence.

Nobel Prize-winning physicist Serge Haroche says the next big revolution will be putting quantum physics to use. Do you agree?

— Yes, he is a quantum physicist of those who are not they go wildI think you're right. Quantum theory, in principle, explains everything, all the properties of matter. The problem is that no one understands it. Understanding that an electron can be here and there at the same time... you don't understand it, but neither do I, who've spent my whole life.

And then?

— You get used to a strange way of thinking that helps you understand your colleagues. What's going on? This world, which we see and which seems like the real world, is a distorted image of the real world. And that real world is at such small distances that we can't observe them directly. Because we learn distances by picking up a glass from the cupboard, putting our finger in the eye of a sister who's annoying us... we learn it at distances of one meter. So the most powerful and best-functioning theory of all is a theory we don't understand, but of course, you must be very stupid and arrogant to think that human beings are capable of understanding everything.

And what would the revolution be?

— There's a second revolution, the one Haroche talks about, that began after the 1980s. It involves applying quantum ideas not to nature, but to information. This may have applications that society may eventually notice, but are difficult to imagine today. But quantum computers will be able to solve problems that classical computers can't. And this, imagine, could have effects, for example, on medicine, with many diseases. But I won't see it, and you just won't.

And in whose hands are quantum computers?

— Currently, they are in the hands of large companies that have a lot of money, of course.

Isn't that a problem?

— With the crises of recent years, there has been a huge transfer of capital from public to private hands. States are practically all bankrupt, and the private sector has never had so many billionaires. A billion is a lot of zeros.

What can be done with this?

— I don't know. The communists will call it a revolution. The thing is, this revolution has never worked. I don't know, because whoever has the money has the power. That's the truth.