 Modern physics regards our currently best theories of particle physics collected in the Standard Model as effective field theories. Effective field theories are low-energy effective approximations to hypothesized more fundamental physical theories whose details are currently unknown. An effective field theory has an in-built limit to its range of applicability, determined by some energy scale \(\Lambda\). When applied to phenomena associated with energies higher than \(\Lambda\) the effective field theory will not deliver correct results. At this point, the more fundamental theory must be considered to which the effective field theory supposedly is a low-energy approximation. For the theories collected in the Standard Model, it is known that they cannot possibly be empirically adequate beyond energies around the Planck scale \(\Lambda_{\textrm{Planck}}\approx 10^{19} \,\textrm{GeV}\), where—presently unknown—quantum gravitational effects become relevant. However, the Standard Model may well be empirically inadequate already at energy scales significantly below the Planck scale. For example, if there is some presently unknown particle with mass \(M\) smaller than the Planck scale \(\Lambda_{\textrm{Planck}}\) but beyond the range of current accelerator technology which interacts with particles described by the Standard Model, the cut-off scale \(\Lambda\) where the Standard Model becomes inadequate may well be \(M\) rather than \(\Lambda_{\textrm{Planck}}\).