Abstract
Unified gauge theories (such as SU(5)) of particle interactions are built on the colour SU(3) and SU(2) × U(1) gauge theories which apparently describe strong and weak and electromagnetic interactions at distances as small as 10−16 cm. In this article the classical reasons for going beyond SU(3) × SU(2) × U(1) to a fully unified theory such as SU(5) are reviewed, and a new reason formulated. A class of imaginary worlds similar to our own is considered and it is shown that unification is possible only in ours. This suggests that the low-energy interactions are unique in that they are constructed to make unification possible.
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Georgi, H. Why unify?. Nature 288, 649–651 (1980). https://doi.org/10.1038/288649a0
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DOI: https://doi.org/10.1038/288649a0
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