It's the largest exceptional group and popular in unified models of particle physics.
For the other exceptional groups:
For example, E7 Toda field theory describes the thermal perturbation of the tricritical Ising model, and the E6 theory the thermal deformation of the tricritical three-state Potts model. These other models are easily distinguished from the magnetically perturbed Ising model by their central charges. It will be interesting to see if physicists can come up with ways to probe these other models experimentally. The E7 model might be easiest— the unperturbed, CFT version has already been realized, for example, in the form of helium atoms on krypton-plated graphite [TFV].DID A 1-DIMENSIONAL MAGNET DETECT A 248-DIMENSIONAL LIE ALGEBRA? by DAVID BORTHWICK AND SKIP GARIBALDI