All About Space

Replacing space-time String theory

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Fundamenta­l particles such as electrons are made of tiny strings that vibrate across ten spatial dimensions, plus one time dimension. This picture manages to avoid infinities when combining quantum theory and general relativity, but it cannot currently be tested.

Loop quantum gravity (LQG)

Space-time is not a smooth fabric, but is made up of a network of tiny stitches instead. This is potentiall­y testable by looking at light reaching us from gammaray bursts (GRBs) in the distant universe.

Modular space-time

Space-time is only a stage when it has actors on it. In other words, interactio­ns between objects create space-time. This can potentiall­y explain the quirks of non-locality and quantum entangleme­nt.

Supergravi­ty

This is the combinatio­n of general relativity with a popular but unproven theory called supersymme­try – the same theory is the leading candidate to explain dark matter.

Causal set theory

Space-time is not a continuous fabric, but does have a structure based on regions that have a link between past and future. It is based on work by David Malament and

Rafael Sorkin.

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