  At any time, there are areas of science where we are standing at the frontier
of knowledge, and can wonder whether we have reached a fundamental limit to
human understanding. What is ultimately possible in physics? I will argue here
that it is ultimately impossible to answer this question. For this, I will
first distinguish three different reasons why the possibility of progress is
doubted and offer examples for these cases. Based on this, one can then
identify three reasons for why progress might indeed be impossible, and finally
conclude that it is impossible to decide which case we are facing.
