2,5/5. A book that shoots in every possible direction and that confuse itself. The worst part is that it spends most of his time in cultural history of time travel and not enough in the philosophical aspect or physics. A least a third of it can be seen has a homage of sort to H. G. Wells, Asimov, Borges, which is interesting in a cultural aspect but I was expecting something way more technical, deeper thinking and it never really happens. A big let down!