"Why, sometimes I've believed as many as six impossible things before breakfast," the Queen told Alice on her adventures through the looking glass. Only six? In software development we believe impossible things all the time, no matter the time of day!

In this talk, however, we are going to take a look at six specific impossible things that shape the limits of what we can develop, all the way from the smallest detail of integer representation to the minefield of task estimation and prioritisation, via the uncertainty of distributed systems and the limits of computability. Once we know our limits, we can work within them to create solutions rather than problems.