Age of the universe

As the world ages, the age of the visible universe is called in modern cosmology. Astronomically it is the since the Big Bang to the present day and past time is according to current knowledge - which also includes the data of the Planck space telescope -

This currently the longest researched period is compared with the shortest physical time, the Planck time (about 10-43 seconds). The time continuum thus extends over about 60 orders of magnitude.

World age and Hubble constant

The world age is approximately the inverse of the Hubble constant H0, which can be determined from the increasing redshift z of distant galaxies:

The underlying phenomenon of expansion of the universe was discovered in the 1920s by Carl Wilhelm Wirtz and Abbé Georges Lemaître.

In 1929 established the U.S. astronomer Edwin Hubble and his colleagues found that an approximately linear relationship between expansion and removal of: the apparent cosmic expansion rate is greater, the greater the distance of each observed galaxy,

The speed of light c.

However, Hubble was given the much too high a value of 500 km s -1 Mpc -1, which would mean a world age of only 2 billion years for this fundamental quantity of cosmology. It was soon realized that this is in contradiction to the geological findings, in particular for time already almost possible age determination of rocks.

Development of assessments

Since 1950, the world each assumed age 4-20 billion years has moved. Within a few years you could correct the value of the Hubble constant at about 50 to 100 km s -1 Mpc -1. The associated debate the cosmologists began about 1970 and lasted until the late 1990s on.

Younger methods gave values ​​for H0 72-77 km s -1 Mpc -1, which would eingrenzte the fluctuation range of the world age to 13.3 to 14 billion years. It is now, however, assume that the Hubble " constant" over time changes, so one speaks also of the Hubble parameter. Whether, however, the cosmic expansion slowed or accelerated long-term, is not yet finally resolved. This issue is related to fundamental questions about the structure of the cosmos together, and in particular its geometry (flat vs.. Hyperbolic universe) and the proportions of dark matter and dark energy. The latest, published in 2013 value for H0 is 67.80 ± 0.77 (km / s) / Mpc.