*Ta-Pei Cheng*

- Published in print:
- 2009
- Published Online:
- February 2010
- ISBN:
- 9780199573639
- eISBN:
- 9780191722448
- Item type:
- chapter

- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199573639.003.0011
- Subject:
- Physics, Particle Physics / Astrophysics / Cosmology

Einstein introduced the cosmological constant in his field equation so as to obtain a static universe solution. This constant energy density corresponds to a negative pressure, giving rise to a ...
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Einstein introduced the cosmological constant in his field equation so as to obtain a static universe solution. This constant energy density corresponds to a negative pressure, giving rise to a repulsive force that increases with distance. The inflationary theory of cosmic origin can provide the correct initial conditions for the standard model of cosmology: solving the flatness, horizon problems, and providing an origin of matter/energy, as well as giving just the right kind of density perturbation for subsequent structure formation. The primordial inflation leaves behind a flat universe, which can be compatible with the observed matter density being less than the critical density and a cosmic age greater than 9 Gyr if there remains a dark energy. This would imply a universe now undergoing an accelerating expansion, which is observationally supported by the measurement of supernovae at high redshift. The cosmological constant and the cosmic coincidence problems point to the need of new fundamental physics.Less

Einstein introduced the cosmological constant in his field equation so as to obtain a static universe solution. This constant energy density corresponds to a negative pressure, giving rise to a repulsive force that increases with distance. The inflationary theory of cosmic origin can provide the correct initial conditions for the standard model of cosmology: solving the flatness, horizon problems, and providing an origin of matter/energy, as well as giving just the right kind of density perturbation for subsequent structure formation. The primordial inflation leaves behind a flat universe, which can be compatible with the observed matter density being less than the critical density and a cosmic age greater than 9 Gyr if there remains a dark energy. This would imply a universe now undergoing an accelerating expansion, which is observationally supported by the measurement of supernovae at high redshift. The cosmological constant and the cosmic coincidence problems point to the need of new fundamental physics.

*Ta-Pei Cheng*

- Published in print:
- 2009
- Published Online:
- February 2010
- ISBN:
- 9780199573639
- eISBN:
- 9780191722448
- Item type:
- book

- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199573639.001.0001
- Subject:
- Physics, Particle Physics / Astrophysics / Cosmology

Einstein's general theory of relativity is introduced in this advanced undergraduate and beginning graduate level textbook. Topics include special relativity, the principle of equivalence, Riemannian ...
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Einstein's general theory of relativity is introduced in this advanced undergraduate and beginning graduate level textbook. Topics include special relativity, the principle of equivalence, Riemannian geometry and tensor analysis, Einstein field equation, as well as many modern cosmological subjects: from primordial inflation, cosmic microwave anisotropy to the dark energy that propels an accelerating universe. The subjects are presented with an emphasis on physical examples and simple applications. One first learns how to describe curved spacetime. At this mathematically more accessible level, the reader can already study the many interesting phenomena such as gravitational lensing, black holes, and cosmology. The full tensor formulation is presented later, when the Einstein equation is solved for a few symmetric cases. Mathematical accessibility, together with the various pedagogical devices (e.g., worked-out solutions of chapter-end problems), make it practical for interested readers to use the book to study general relativity and cosmology on their own. In this new edition of the book, presentations on special relativity and black holes are augmented by new chapters. Other parts of the book are updated to include new observation tests of general relativity (e.g., the double pular system) and more recent evidence for dark matter and dark energy.Less

Einstein's general theory of relativity is introduced in this advanced undergraduate and beginning graduate level textbook. Topics include special relativity, the principle of equivalence, Riemannian geometry and tensor analysis, Einstein field equation, as well as many modern cosmological subjects: from primordial inflation, cosmic microwave anisotropy to the dark energy that propels an accelerating universe. The subjects are presented with an emphasis on physical examples and simple applications. One first learns how to describe curved spacetime. At this mathematically more accessible level, the reader can already study the many interesting phenomena such as gravitational lensing, black holes, and cosmology. The full tensor formulation is presented later, when the Einstein equation is solved for a few symmetric cases. Mathematical accessibility, together with the various pedagogical devices (e.g., worked-out solutions of chapter-end problems), make it practical for interested readers to use the book to study general relativity and cosmology on their own. In this new edition of the book, presentations on special relativity and black holes are augmented by new chapters. Other parts of the book are updated to include new observation tests of general relativity (e.g., the double pular system) and more recent evidence for dark matter and dark energy.

*Ta-Pei Cheng*

- Published in print:
- 2015
- Published Online:
- August 2015
- ISBN:
- 9780199693405
- eISBN:
- 9780191803130
- Item type:
- chapter

- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199693405.003.0010
- Subject:
- Physics, Particle Physics / Astrophysics / Cosmology

The universe experienced a huge expansion in the earliest moments of the big bang. This cosmic inflationary epoch (with a large cosmological constant) can provide the correct initial conditions for ...
More

The universe experienced a huge expansion in the earliest moments of the big bang. This cosmic inflationary epoch (with a large cosmological constant) can provide the correct initial conditions for the standard Friedmann–Lemaître–Robertson–Walker cosmology. Inflation left behind a flat universe that could be compatible with the observed matter density and a cosmic age if there remained a small but nonvanishing cosmological constant—a dark energy. This would imply that the expansion of the universe is now accelerating. Measurements of high-redshift supernovae, together with the anisotropy of the cosmic microwave background and large-structure surveys, have provided a concordant picture of a flat universe dominated by dark energy. Most matter is exotic cold dark matter, more than five times the amount of ordinary (baryonic) matter. In this Λ CDM cosmology, the cosmic age comes out to be close to the Hubble time of 14 billion years.Less

The universe experienced a huge expansion in the earliest moments of the big bang. This cosmic inflationary epoch (with a large cosmological constant) can provide the correct initial conditions for the standard Friedmann–Lemaître–Robertson–Walker cosmology. Inflation left behind a flat universe that could be compatible with the observed matter density and a cosmic age if there remained a small but nonvanishing cosmological constant—a dark energy. This would imply that the expansion of the universe is now accelerating. Measurements of high-redshift supernovae, together with the anisotropy of the cosmic microwave background and large-structure surveys, have provided a concordant picture of a flat universe dominated by dark energy. Most matter is exotic cold dark matter, more than five times the amount of ordinary (baryonic) matter. In this *Λ* CDM cosmology, the cosmic age comes out to be close to the Hubble time of 14 billion years.