What is the critical temperature for Bose–Einstein condensation of a gas of electron pairs at a density of 10²² cm⁻³, according to the ideal gas formula of Section 11.1, assuming that the electrons have the same effective mass as in vacuum? How does this Tc compare to typical superconductor T_c values of a few kelvin? This points out that the superconducting T_c discussed in this section is fundamentally related to pair breaking; as long as the pairs are stable, they are well below the critical temperature for Bose–Einstein condensation. It has been suggested that some materials might have the reverse: The T_c for pair formation could be above the temperature for condensation, in which case preformed Cooper pairs could exist without superconductivity.