Measuring Spacetime: from Big Bang to Black Holes

Fig 6: Summary of the spacetime issues discussed in this article. One can use photons and astronomical objects as test particles to measure spacetime over 22 orders of magnitude in scale, ranging from the cosmic horizon (probing the global topology of and curvature of space - top) to distant supernovae (giving evidence of dark energy) down to galaxies (giving evidence for dark matter), galactic nuclei and binary stellar systems (giving evidence for black holes). High-res jpg version here.

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Max Tegmark,

Nerd abstract:

Observational constraints on spacetime are reviewed, focusing on how the underlying physics (dark matter, dark energy, gravity) can be tested rather than assumed.

Popular abstract:

Space is not a boring static stage on which events unfold over time, but a dynamic entity with curvature, fluctuations and a rich life of its own which is a booming area of study. Spectacular new measurements of the cosmic microwave background, gravitational lensing, type Ia supernovae, large-scale structure, spectra of the Lyman alpha forest, stellar dynamics and x-ray binaries are probing the properties of spacetime over 22 orders of magnitude in scale. Current measurements are consistent with an infinite flat everlasting universe containing about 30% cold dark matter, 65% dark energy and at least two distinct populations of black holes.

Reference info:

astro-ph/0207199. A slightly abbreviated version of this paper was published as an invited review in Science, 296, 1427-1433 (2002). The full text and pdf of this version is available here and the abstract is here.

Relevant links:

The paper is heavily based on two longer articles on spacetime to 0th order (Tegmark 2001) and spacetime to 1st order (Tegmark & Zaldarriaga 2002).
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This page was last modified July 10, 2002.