Editing Dimensionless physical constant (section)

== Characteristics ==
There is no exhaustive list of such constants but it does make sense to ask about the minimal number of fundamental constants necessary to determine a given physical theory. Thus, the [[Standard Model]] requires 25 physical constants.  About half of them are the [[mass]]es of [[fundamental particle]]s, which become "dimensionless" when expressed relative to the [[Planck mass]] or, alternatively, as coupling strength with the Higgs field along with the [[gravitational constant]].<ref>Kuntz, I., ''Gravitational Theories Beyond General Relativity'', (Berlin/Heidelberg: Springer, 2019), [https://books.google.com/books?id=xrWZDwAAQBAJ&pg=PA58&redir_esc=y#v=onepage&q&f=false pp. 58–61].</ref>

Fundamental physical constants cannot be derived and have to be [[metrology|measured]]. Developments in physics may lead to either a reduction or an extension of their number: discovery of new particles, or new relationships between physical phenomena, would introduce new constants, while the development of a more fundamental theory might allow the derivation of several constants from a  more fundamental constant.

A long-sought goal of theoretical physics is to find first principles ([[theory of everything]]) from which all of the fundamental dimensionless constants can be calculated and compared to the measured values.

The large number of fundamental constants required in the Standard Model has been regarded as unsatisfactory since the theory's formulation in the 1970s. The desire for a theory that would allow the calculation of particle masses is a core motivation for the search for "[[Physics beyond the Standard Model]]".