Book contents
- Frontmatter
- Contents
- Preface to the Russian edition
- Preface to the English edition
- 1 Origins of thinking about time
- 2 Science of time is born
- 3 Light
- 4 The pace of time can be slowed down!
- 5 Time machine
- 6 Time, space and gravitation
- 7 Holes in space and time
- 8 Energy extracted from black holes
- 9 Towards the sources of the river of time
- 10 Journey to unusual depths
- 11 Grand Unification
- 12 Sources
- 13 What produces the flow of time and why in a single direction only?
- 14 Against the flow
- 15 Can we change the past?
- Conclusion
- Name index
- Subject index
6 - Time, space and gravitation
Published online by Cambridge University Press: 04 May 2010
- Frontmatter
- Contents
- Preface to the Russian edition
- Preface to the English edition
- 1 Origins of thinking about time
- 2 Science of time is born
- 3 Light
- 4 The pace of time can be slowed down!
- 5 Time machine
- 6 Time, space and gravitation
- 7 Holes in space and time
- 8 Energy extracted from black holes
- 9 Towards the sources of the river of time
- 10 Journey to unusual depths
- 11 Grand Unification
- 12 Sources
- 13 What produces the flow of time and why in a single direction only?
- 14 Against the flow
- 15 Can we change the past?
- Conclusion
- Name index
- Subject index
Summary
Everyone knows that the space of the Universe is three-dimensional. This means that space is characterized by length, width and height. The same is true for any body. Somewhat differently, the position of a point in space is characterized by three numbers known as coordinates. If we draw straight lines or planes or complicated curves through space, their properties are described by the laws of geometry. These laws have been known to man since ancient times and were compiled by Euclid in the 3rd century bc. Euclidean geometry is studied in schools as a harmonious system of axioms and theorems that describe all properties of lines, surfaces and solids.
If we wish to study not only the spatial position but also processes occurring in three-dimensional space, we need to add time as well. An event taking place at some point is characterized by the position of this point, that is, by indicating three numbers, and by a fourth number, that is, the moment of time at which the event occurred. For the event the time is its fourth coordinate. In this sense we say that our world is four-dimensional.
All this is well known, of course. Then why wasn't this formulation of four-dimensionality treated as serious and fraught with new knowledge before the theory of relativity was born? The catch lay in the fact that the properties of space and time seemed to be too dissimilar.
- Type
- Chapter
- Information
- The River of Time , pp. 81 - 94Publisher: Cambridge University PressPrint publication year: 2001