NEWS

# SAVVAS DIMOPOULOS

A professor of physics at Stanford University in the US since 1979, Savvas Dimopoulos introduced the hypersymmetrical model, along with Howard Georgi in 1981, a theoretical attempt to go beyond the «standard model.» In 1998, he proposed the theory of large extra dimensions (with Nima Arkani-Hamed and Gia Dvali) that links the weakness of gravity to the existence of new dimensions while making experimental links between quantum gravity, the theory of Chords and black holes. Born in Istanbul, he finished high school in Athens and went to the USA to study in 1970. What is the focus of particle physics research at the moment? The fundamental problem we are trying to resolve at the moment is the hierarchy of forces. Gravity is a very weak force compared to electricity. Gravitational force between electrons and protons is 40 times weaker than electrical force. The resolution of this problem will come from the discovery of new particles that could give us some answers as to where gravity goes. Could you give us an example of this «unbearable lightness of gravity»? A magnet can attract a piece of metal, it can even lift it up off the ground. So the force of the magnet is greater than that of the entire planet. This just gives an idea of how much stronger magnetism is than gravity. And that’s the problem. The basic idea of physics is unification. That is, to be able to explain all phenomena using the same simple equations. The microcosm as well as the universe. Precisely. That is the dream of physics. Of course, we have come a long way. The ancient Greeks spoke about four elements that explained all phenomena, Newton’s theory described heavenly phenomena using the same theory as for earthbound phenomena, Maxwell explained the unification of electricity, magnetism and light during the previous century. More recently, in the 1960s and 1970s, the unification of electromagnetic and weak forces was achieved, leading to the standard model. Unification of the world means unifying the forces as well. That is, all forces should be about equal, but then why is gravity so weak? So we are missing something. Nowadays, is it only gravity that is not unified? Yes. The stronger, electromagnetic and weak forces are unified based on the theory of hypersymmetry. I hope the HLC accelerator due to open at CERN in 2007 will provide answers. We can understand a three- (or, with time, a four-) dimensional system. But what do we mean when we talk about 11 dimensions? Where are they? The three known dimensions are theoretically of infinite size, but the others are small. That is why we can’t see them. We need «microscopes,» which in this case are the accelerators. The fact that we can’t perceive them doesn’t mean they don’t exist. When, for example, we see a long narrow pipe from far away we think it only has one dimension, length. We have to get close up to see its height and width. Where things are infinitely small or infinitely large, is that where God is? If you are talking about a God who is interested in whether I went to church yesterday or whether I am a good person, I don’t think such a being exists. If we are talking about discovering the laws of nature, then we can say that we are entering «God’s mind.» Generally, scientists have a very limited concept of God. What are you studying at the moment? The effects of these theories. For example, the Chord theories predict the existence of many universes. In the past, we believed there was one solar system. Then we discovered there are billions of solar systems, with different natural laws. Such a hypothesis has many important philosophical and scientific repercussions. For example, the distance between the Earth and the sun is precisely what is required so that we neither burn nor freeze to death. If there was just one solar system, one might say it was the amazing invention of a God who put us at the right distance (from the sun). If there are billions of solar systems, it is logical to assume that life simply appeared where environmental conditions happened to favor it. That is, we are living where we are able to live. What is the attraction of physics? For me, it is the most important thing someone can do. We are trying to understand what the universe is made of, where we came from and where we are going, why we exist. They are the questions we ask when we are children. When we grow up we get over them, without having found any answers. But we never forget them. During the 1960s in Greece, we had a lot of politicians who told lies. That is why I decided to turn to science, where truth can be specific.