What are 2nd and 3rd generation fermions? Let’s take neutrinos as an example. Interactions between electron neutrinos and photons could create the (unstable) variants muon neutrino and tau neutrino. These variants can be seen as neutrinos with one or two serially connected photons (the information of photons) on one of the arms of the neutrino. As a result, these ‘particles’ are, as a whole, more complex and have more ‘mass’. However, they are relatively unstable because they can easily release the ‘photons’ again. The same is conceivable for other fermions.