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| > > > Contatti Ex Libris Comunicazione s.r.l. Torino - via Palazzo di Città 21 Roma - via Zanardelli 34 Milano - via Giulio e Corrado Venini 25 tel +39 011 5695614 fax +39 011 19785300 e-mail ufficiostampa@exlibris.it www.exlibris.it Responsabile Ufficio Stampa |
1 novembre 2008 ABSTRACT/INTERVISTA Paul J. Steinhardt: Oltre il Big Bang Steinhardt will deliver a lecture based on his book Endless Universe: Beyond the Big Bang, co-written with Neil Turok (Cambridge University), in which he will describe a new, radical alternative to the Big Bang Theory for explaining the origin and evolution of the universe. The alternative, known as the Cyclic Theory, proposes that the universe has no beginning and no end and that matter, galaxies, stars and life undergo endlessly repeating cycles of creation,destruction and re-creation. Scientists throughout the world are working at a feverish pace to test these two competing ideas. The following questions and answers highlight what is at stake: Are you telling us that the Big Bang Theory is completely wrong? No, the two Big Bang Theory and the Cyclic Theory have a lot in common. They both agree that the universe has been expanding and cooling over the last 14 billion years and they agree on the details of how the current galaxies and stars formed. As a result, all the astronomical tests thus far that support the Big Bang Theory also agree with the Cyclic Theory. Where they disagree is on what happened beforehand and what will happen in the future. The Big Bang Theory say there was no “beforehand.” Space, time and matter all sprang into existence 14 billion years ago in the event called “the big bang,” and all the events responsible for structure of the universe seen today occurred within the first instant after the big bang. The current Big Bang Theory also says that the universe will expand forever at an increasing rate, approaching a permanently empty wasteland in less than a trillion years. The Cyclic Theory agrees that there was some violent event 14 billion years ago – we can still call it a big bang – but this was not the beginning of space and time. The key events causing the creation of matter, radiation, galaxies and stars occurred billions of years before the bang. Furthermore, there was not just one bang. The evolution of the universe is cyclic and eternal, with big bangs occurring once every trillion years or so, each one accompanied by the creation of new matter and radiation that forms new galaxies, stars, planets, and presumably life. Hence, the nature of time and “eternity” and our philosophical outlook on our place in the universe are radically different in the two pictures. Why consider a new theory if the Big Bang Theory is already successful? Over the last few decades, more and more elements have had to be added to the Big Bang Theory to make it consistent with what we observe. To explain why the universe is so uniform, a new feature called “inflation” has been added. To explain the formation of structure, dark matter has been added. The recent discovery that the expansion of the universe has begun to speed up has required the addition of yet something else, called dark energy. Each of these elements has been added one by one to make today’s Big Bang Theory a kind of patchwork of disconnected ideas. Even with all that, there are some questions about whether this picture really works. And, behind it all, there is the assumption that the big bang is the beginning of everything – something that has never been successfully explained by fundamental physics. The two of us wanted to see if a completely different history of the universe is possible in which all the elements fit together in a tight and natural way. We saw that recent developments in fundamental physics – namely, string theory – offered a new possibility for the big bang itself – not as a beginning but rather as a collision of two parallel worlds along an extra invisible dimension. Much to our surprise, we found we could use this picture to reformulate the history of the universe – recovering all the successful predictions of the conventional Big Bang Theory. We now recognize the same Cyclic evolution can occur in ways that do not require parallel worlds, but this remains a possible and most intriguing version. Why should one care about which theory is correct? Here is our chance to answer the question of the ages: where did the universe came from and where is headed? We have narrowed the possibilities to two radically different ideas, and we have the technology in hand to decide which is correct. The scientific resolution of this competition will surely be one of the great achievements of the millennium. Furthermore, the answer may determine the degree to which our universe is set by chance or design. In both theories, the part of the universe we observe is a tiny patch of a much larger, perhaps infinite space. In the current Big Bang theory, different parts of the universe have widely different physical properties and, some theorists believe, different physical laws. The properties of our region are set purely by random chance. In the Cyclic Theory, the universe is the same everywhere, restoring the hope that the universe is simple and comprehensible. How do we decide which theory is the correct? As always in science, Nature decides. The Cyclic Theory leaves a distinctive pattern of gravitational waves (ripples of space-time that propagate through space) and variations in the distribution of energy that are very different from the one expected in the Big Bang Theory. Experimental groups throughout the world are racing to test these predictions. Why write this book now? Most science books are written after ideas have been around for many years and already well established. We thought this was an opportunity to write about a new scientific idea at a time when it is first emerging – to capture science as it is happening through the eyes of scientists directly involved, including a depiction of the real struggles and risk-taking involved in developing new scientific ideas. In this way, we hope the book not only conveys the exciting new ideas themselves, but also gives the reader an insider’s view on how science really works. Paul J. Steinhardt Albert Einstein Professor of Science presso il Dipartimento di Fisica e il Dipartimento di Scienze Astrofisiche della Princeton University. > indietro > scarica doc |
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