[eBook] - Physics - Stephen Hawking - Book - Theory of Everything

[eBook] - Physics - Stephen Hawking - Book - Theory of Everything

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Global Knowledge Foundation 1 THE THEORY OF EVERYTHING Stephen Hawking The following is a summary of Stephen Hawking's talk as printed by The Bulletin of the University of Toronto . On April 29, 1980, I gave my inaugural lecture as the Lucasian Professor of mathematics at Cambridge. My title was, Is the End in Sight for Theoretical Physics? I described the progress we had already made in the last hundred years in understanding the universe and asked what the chances were that we would find a complete unified theory of everything by the end of the century. Well, the end of the century is almost here. Although we have come a long way, particularly in the last three years, it doesn’t look as if we are going to quite make it. In my 1980 lecture I described how we had broken down the problem of finding a theory of everything into a number of more manageable parts. First of all we had divided the description of the universe around us into two parts. One part is a set of local laws that tell us how each region of the universe evolves in time, if we know its initial state, and how it is affected by other regions. The other part is a set of what are called boundary conditions. These specify what happens at the edge of space and time. They determine how the universe begins and, maybe, how it ends. Many people, including probably a majority of physicists, feel that the task of theoretical physics should be confined to the first part, that of formulating local laws that describe how the universe evolves in time. They would regard the question of how the initial state is determined as being beyond the scope of physics and belonging to the realms of metaphysics or religion. But I’m an unashamed rationalist. In my opinion the boundary conditions of the universe that determine its initial state are as legitimate a matter for scientific inquiry as are the laws that govern how it evolves. In the early 1960s the forces that were known to physics were classified into four categories that seemed to be separate and independent of each other. The first of the four categories was the gravitational force, which is carried by a particle called the graviton. Gravity is by far the weakest of the four forces. However, it makes up for its low strength by having two important properties. The first is that it is universal. That is, it affects every particle in the universe in the same way. All bodies are attracted to each other. None are unaffected or repelled by
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[eBook] - Physics - Stephen Hawking - Book - Theory of Everything

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