If superstrings will not yield the ultimate answers, then in which direction should we continue our research? Or did we throw ourselves so far into the world of the unknown and unintelligible that we are about to drown in nonsense? Are we burying ourselves beneath so many impossible questions that we should be considered lost for science? Does it make any sense at all to speculate about a Theory of Everything in this strange world of Planck numbers? Perhaps the title of this chapter makes you fear the worst.

Nothing excites our curiosity more than the unintelligible. What is so curious about the world at the Planck length is that no model at all can be found that gives a reasonably self-consistent description of particles that influence each other with such strong gravitational forces, while at the same time obeying the laws of quantum mechanics. So, even if we had been able to perform experiments with particles that hit each other with Planckian energies, we would not have known how to compare the results with a theory. There is work here to do for physicists: make a theory. We do not care too much how such a theory describes the gravitational force, but there are quite a few demands on our list that make the creation of a candidate theory extremely difficult. As I explained at the end of the preceding chapter, superstring theory came close to doing just this, but it may well fail to fulfil its promises.