Hat do you believe to be the truth, even if you can’t prove it?» was the question that Kathimerini posed to 16 Greek mathematicians, biologists, physicists, doctors, academics, poets, writers, composers and actors, inspired by an article in the e-magazine Edge. Most say that there is no evidence for the existence of God or an afterlife, or of love, for that matter. Even in this technological age, faith is the answer to fundamental questions of human existence. We believe there is an afterlife, or that love can save the world; we believe in the existence of instinct and imagination, that disease can be overcome, even when we have no proof. We believe that there have always been great ideas and great works, that we are not alone in the universe and that although we live in an age where everything needs to be scientifically proven, there are countless things for which proof is superfluous. Professor Giorgos Koumandos, president of the National Bioethics Commission: I don’t believe in anything for which there is no proof. Christos A. Homenidis, writer: Given that the universe is of inconceivable dimensions in human terms, I believe that every unfulfilled version of our recent or past history has taken place somewhere else. On some far-off planet or galaxy, Napoleon has won the Battle of Waterloo, and Europe has gone in a completely different direction than the one we know. On some far-away star that is unseen by even the strongest telescope on earth, there is an Omonia Square with a lake in the middle, full of ducks swimming about. A couple standing on a wooden bridge is feeding the ducks, and laughing. It is you and I, who have just met and fallen head over heels in love. In another world, you have just left me for my best friend and in another, I have just run you over with my motorbike while you, a little girl, were crossing the coast road with your grandmother and I, a crazy teenager, was doing «wheelies» and killed you. You might ask what the difference is among the millions of different versions of the stories of our lives, since we experience only the one and are ignorant of all the others. But perhaps the dreams we have every night, the books we write and read, the films we see and direct are just reports from those parallel worlds. Nikos Katsaros, president of the Unified Food Inspection Agency (EFET) and research director of the Physics and Chemistry Institute at the Democritus Nuclear Research Center: I believe that the world was created out of nothing but I can’t prove it. Scientific theories put forward in recent years have reversed previous religious doctrines and do not rule out the possibility that the universe was, in fact, created out of nothing. Nanos Valaoritis, poet: I believe that poems pre-exist. Plato said that ideas pre-existed. It is not as illogical as it sounds. Mathematicians – again according to Plato – accept that they discover a theorem; they don’t invent it. It must be the same with other things. The possibility pre-existed. Aristotle said we are striving for perfection. Plato said that we are part of perfection without being able to achieve it. We can’t prove it. I am not the only poet who believes that. The Indian Mahabarata was dictated to the god of writing. The poem «Milton» was dictated to William Blake by a voice, from another great poem somewhere in the hereafter, but where? It is a metaphysical concept but not illogical. Giorgos Andreou, composer: From a very young age, I believed that every person is a player in a secret scenario beyond the visible life and at the same time has a secret destination. That is, a person might be suffering at some point, but that fact could be taking him somewhere that is not apparent to his conscious mind. At some point he might become aware of it, or he might never. I believe there is a second level of destination and realization, but I can’t prove it. Dimitris Nanopoulos, president of the National Research and Technology Council: The sciences, particularly physics, are not dogmatic but are based on experimentation which is the final judge of whether a theory is correct or not. But instinct and imagination are the theoretical physicist’s weapons and sometimes we go way, way ahead and wait for confirmation. Within that framework, what I am waiting to «hear» is whether the universe is the product of the chance collision between two (D) membranes that happened to emerge from the quantum vacuum, an image that will explain the Big Bang. I absolutely believe that universology is the best thing to raise human life above the level of farce and give it something of the nobility and grace of tragedy. Thanassis Fokas, professor of non-linear mathematical science at Cambridge University: Why are the main laws of nature expressed in mathematical language? In other words, why is it that the only way we can understand the world around us is based on mathematical structures? I believe there is a logical explanation for this «mystery.» Indeed, I believe that the most basic characteristic of the brain’s functioning is its ability to create associations and that this ability unavoidably leads to the creation of mathematical language. Consequently, and even if there are other ways to reproduce the world that are just as fundamental as that based on mathematics, the brain only understands the mathematical model. I cannot prove that deterministic relationship between associations and mathematics, but if we solve that problem – that is, if we understand precisely how the brain computes – then our ability to discover mathematical structures (and therefore understand the universe) will increase astoundingly. Christos Papadimitriou, professor at the University of California at Berkeley and member of the US Academy of Arts and Sciences: Unfortunately, we can prove very few of the valid suspicions we have about life and about science and mathematics. For myself, the most basic conjecture of this kind has to do with the limitations of computers. Today, computers are so fast that one could say that no problem is too big for them. So the surprising thing is that there are many important problems that computers cannot only not solve satisfactorily, but which I suspect cannot ever be solved. It would appear that it would take longer than the life of the universe, or computers larger than galaxies, or both. That has not been absolutely proved, but it is a very well-known mathematical conjecture which is called the «P vs NP problem,» one of the seven mathematical «Millennium Problems» for which the Clay Mathematics Institute allocated a million dollars each a few years ago. Mania Papadimitriou, actress: I am convinced that if some people wasted less money, large sectors of the earth’s population would live better and the only reason this does not happen is because of the greed of these few. I believe that this is not self-evident because what I call greed, economic theory calls legitimate profit. Lefteris Papadopoulos, lyricist, poet and journalist: I believe, or rather I hope, that there is another life. I don’t like the idea that we might have come into the world, fallen in love, had children, written books and songs, made lovely tables and chairs, shoes and paintings, just to leave again. I think that is most unjust. Panayiotis Tetsis, artist: I believe what the astronomers, the space scientists say, that there is not one universe but many, that a star may have lived billions of years ago and we are just seeing it now. That is something I cannot conceive of; I cannot imagine what is in that vacuum between the universes. Eftychios Voridis, professor of medicine at Athens University: One can believe in things that could be proven in the future. Whatever we do in our lives cannot be proven. So I believe that in future a drug or a vaccine will be found for coronary disease, for which the mechanisms are inflammation. We have indications about these but not the means to prevent them. Christos Yiannaras, professor of philosophy at Panteion University: I believe in my abstract judgments, conclusions drawn from my experience. I say that a particular person is sensitive, a friend is faithful, one artist is more talented than another. I can’t prove the validity of my personal judgments. I simply believe them. I believe in observations expressed in poetry which are confirmed by my experience. Odysseas Elytis said that what we don’t know shines within us. I believe that. I believe in the knowledge born of love, when «suddenly» there is the miracle of mutuality. Then I know the other person in a manner that no collection of information can provide. I believe in the truth in art. I know Mozart, Van Gogh or Cavafy better than someone who was their neighbor but who passed them by every day without acknowledging them. Dimitris Nollas, writer: The truth is he who stands by me and to whom I answer for my acts. A truth that has no need of proof, but faith. Dimitris Kataleifos, actor: I believe that people’s sole purpose on earth is to succeed in being good. I don’t know if there is a life hereafter or whether kindness is ever rewarded. But I do believe that it is the only reason for existence. We are born in order to be good to others, and that is incredibly difficult. Those who manage it deserve to have lived. Christos Zerefos, secretary of the International Ozone Commission and professor of geology at Athens University: I don’t believe in anything that can’t be proved. For me, the truth is that which can be scientifically proven. For example, that humans have a considerable influence on the planet. It might not be obvious, but it is shown by nature itself.