The success of advanced microbeam facilities at third generation synchrotron sources have inspired us to ask ultimate questions such as how small an x‐ray beam diameter can be made. With the hope of more brilliant Energy Recovery Linac or X‐ray Free Electron Laser sources due to arrive in the next decade, it appears possible to think of fluorescent x‐ray experiments that can be performed on even a single impurity atom in a silicon wafer, for instance. Not all x‐ray optical developers are yet convinced, however, so there is critical need to assess whether in principle this can really be done or not. We are optimistic that 1 nm diameter x‐ray beams can be made of sufficient flux from future sources or even demonstration experiments at lower count rates from 3rd generation sources if it turns out to be worthwhile to actively develop optics and methods that vastly exceed the current x‐ray microbeam capabilities.