Bran cosmology

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The brane cosmology is a common (but not only) in the context of string theory theory discussed, which assumes that in addition to the four in the cosmology usual space-time dimensions , one or more additional dimensions ( extra dimensions ) exist. The four-dimensional space-time is thus a hyperplane , the so-called bran (of membrane ), which is embedded in a higher-dimensional space-time, the so-called bulk . Ordinary matter is trapped on the bran, which means that it cannot escape into the extra dimension (s). The additional dimensions are therefore not perceptible in everyday life. However, they have an influence on the expansion behavior of the universe , which enables an experimental check of this fact.

history

Already in 1914 Gunnar Nordström and in 1919 Theodor Kaluza in a letter to Albert Einstein and in 1926 also Oskar Klein suggested a fifth dimension ( Kaluza-Klein theory ). In this way they wanted to achieve a union of gravitation and electromagnetic force . The idea of ​​additional dimensions was later taken up by string theory . What these theories have in common is that the extra dimensions are compacted; H. "Rolled up". The compactification radius is roughly the Planck length . This means that the additional dimensions are so small that they cannot be perceived either in everyday life or in previous experiments. An object moving in the direction of one of these dimensions would arrive back at its starting point almost instantly.

It was not until the late 1990s that a model was developed, the Randall-Sundrum model , which enabled an infinitely large or macroscopically large, i.e. non-compacted, extra dimension. The aim of this model was to solve the hierarchy problem, i.e. H. to find an explanation for the fact that gravity is orders of magnitude weaker than the other interaction forces. The Randall-Sundrum model represents the first brane model. In the course of the last few years, a large number of other models have been developed, some of which differ significantly from the original model in terms of their effects (e.g. on the expansion of the universe). The branch cosmology is therefore not a uniform theoretical structure, but consists of many different models.

So far, no experimental evidence of another dimension has been found. The analysis of experiments of the Large Hadron Collider (LHC) at CERN in December 2010 also considerably limits the possibilities of theories with infinitely large extra dimensions.

See also

literature

Web links

Individual evidence

  1. ↑ CMS Collaboration: Search for Microscopic Black Hole Signatures at the Large Hadron Collider,