A Brief History of Time by Stephen Hawking. Read online, or download in secure EPUB format. A Brief History of Time by Stephen Hawking Free ePub. A Brief History of Time by Stephen Hawking Free Ebook. A Brief History of Time by. Was there a beginning of time? Could time run backwards? Is the universe infinite or does it have boundaries? These are just some of the questions considered.
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Book for book lovers on time,space and universe. Identifier StephenHawkingABriefHistoryOfTime. Identifier-arkark://t4tj2df Ocr ABBYY. It is an update and rewrite of Hawking's A Brief History of Time. The book is in epub format hence not viewable unless an epub reader is. Stephen Hawking - A Brief History of Time Could time run backwards? To this day ABrief History of Time remains a staple of the scientific.
External links 7 Overview A Brief History of Time attempts to explain a range of subjects in cosmology , including the Big Bang , black holes and light cones , to the nonspecialist reader. Its main goal is to give an overview of the subject but, unusual for a popular science book, it also attempts to explain some complex mathematics. The edition of the book and subsequent editions discuss the possibility of time travel and wormholes and explore the possibility of having a universe without a quantum singularity at the beginning of time. Early in , Hawking first approached Simon Mitton , the editor in charge of astronomy books at Cambridge University Press , with his ideas for a popular book on cosmology. Mitton was doubtful about all the equations in the draft manuscript, which he felt would put off the downloaders in airport bookshops that Hawking wished to reach.
The edition of the book and subsequent editions discuss the possibility of time travel and wormholes and explore the possibility of having a universe without a quantum singularity at the beginning of time. Early in , Hawking first approached Simon Mitton , the editor in charge of astronomy books at Cambridge University Press , with his ideas for a popular book on cosmology.
Mitton was doubtful about all the equations in the draft manuscript, which he felt would put off the downloaders in airport bookshops that Hawking wished to reach. It was with some difficulty that he persuaded Hawking to drop all but one equation. The book does employ a number of complex models, diagrams and other illustrations to detail some of the concepts it explores.
Editions First edition. It included an Introduction by Isaac Newton Stephen Hawking was a legend even then. Hawking wrote his own introduction for later editions. This hardcover edition contained full color illustrations and photographs to help further explain the text, as well as the addition of topics that were not included in the original book. It features the same text as the one published in , but was also released in paperback and has only a few diagrams included.
Instead, we may have to use different reflections of the underlying theory in different situations. It might be like our being unable to represent the surface of the earth on a single map and having to use different maps in different regions.
This would be a revolution in our view of the unification of the laws of science but it would not change the most important point: that the universe is governed by a set of rational laws that we can discover and understand.
On the observational side, by far the most important development has been the measurement of fluctuations in the cosmic microwave background radiation by COBE the Cosmic Background Explorer satellite and other collaborations. These fluctuations are the finger-prints of creation, tiny initial irregularities in the otherwise smooth and uniform early universe that later grew into galaxies, stars, and all the structures we see around us.
Their form agrees with the predictions of the proposal that the universe has no boundaries or edges in the imaginary time direction; but further observations will be necessary to distinguish this proposal from other possible explanations for the fluctuations in the background. However, within a few years we should know whether we can believe that we live in a universe that is completely self-contained and without beginning or end.
He described how the earth orbits around the sun and how the sun, in turn, orbits around the center of a vast collection of stars called our galaxy. At the end of the lecture, a little old lady at the back of the room got up and said: "What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise.
What do we know about the universe, and how do we know it? Where did the universe come from, and where is it going? Did the universe have a beginning, and if so, what happened before then?
What is the nature of time? Will it ever come to an end? Can we go back in time?
Recent breakthroughs in physics, made possible in part by fantastic new technologies, suggest answers to some of these longstanding questions. Someday these answers may seem as obvious to us as the earth orbiting the sun - or perhaps as ridiculous as a tower of tortoises. Only time whatever that may be will tell. As long ago as BC the Greek philosopher Aristotle, in his book On the Heavens, was able to put forward two good arguments for believing that the earth was a round sphere rather than a Hat plate.
First, he realized that eclipses of the moon were caused by the earth coming between the sun and the moon. The earth's shadow on the moon was always round, which would be true only if the earth was spherical. If the earth had been a flat disk, the shadow would have been elongated and elliptical, unless the eclipse always occurred at a time when the sun was directly under the center of the disk. Second, the Greeks knew from their travels that the North Star appeared lower in the sky when viewed in the south than it did in more northerly regions.
Since the North Star lies over the North Pole, it appears to be directly above an observer at the North Pole, but to someone looking from the equator, it appears to lie just at the horizon. From the difference in the apparent position of the North Star in Egypt and Greece, Aristotle even quoted an estimate that the distance around the earth was , stadia.
It is not known exactly what length a stadium was, but it may have been about yards, which would make Aristotle's estimate about twice the currently accepted figure. The Greeks even had a third argument that the earth must be round, for why else does one first see the sails of a ship coming over the horizon, and only later see the hull? Aristotle thought the earth was stationary and that the sun, the moon, the planets, and the stars moved in circular orbits about the earth.
He believed this because he felt, for mystical reasons, that the earth was the center of the universe, and that circular motion was the most perfect.
This idea was elaborated by Ptolemy in the second century AD into a complete cosmological model.
The earth stood at the center, surrounded by eight spheres that carried the moon, the sun, the stars, and the five planets known at the time, Mercury, Venus, Mars, Jupiter, and Saturn Fig. The planets themselves moved on smaller circles attached to their respective spheres in order to account for their rather complicated observed paths in the sky.
The outermost sphere carried the so-called fixed stars, which always stay in the same positions relative to each other but which rotate together across the sky. What lay beyond the last sphere was never made very clear, but it certainly was not part of mankind's observable universe. Ptolemy's model provided a reasonably accurate system for predicting the positions of heavenly bodies in the sky.
But in order to predict these positions correctly, Ptolemy had to make an assumption that the moon followed a path that sometimes brought it twice as close to the earth as at other times. And that meant that the moon ought sometimes to appear twice as big as at other times! Ptolemy recognized this flaw, but nevertheless his model was generally, although not universally, accepted. It was adopted by the Christian church as the picture of the universe that was in accordance with Scripture, for it had the great advantage that it left lots of room outside the sphere of fixed stars for heaven and hell.
A simpler model, however, was proposed in by a Polish priest, Nicholas Copernicus. At first, perhaps for fear of being branded a heretic by his church, Copernicus circulated his model anonymously.
His idea was that the sun was stationary at the center and that the earth and the planets moved in circular orbits around the sun. Nearly a century passed before this idea was taken seriously.
Then two astronomers - the German, Johannes Kepler, and the Italian, Galileo Galilei - started publicly to support the Copernican theory, despite the fact that the orbits it predicted did not quite match the ones observed.
In that year, Galileo started observing the night sky with a telescope, which had just been invented. When he looked at the planet Jupiter, Galileo found that it was accompanied by several small satellites or moons that orbited around it. This implied that everything did not have to orbit directly around the earth, as Aristotle and Ptolemy had thought. It was, of course, still possible to believe that the earth was stationary at the center of the universe and that the moons of Jupiter moved on extremely complicated paths around the earth, giving the appearance that they orbited Jupiter.