I'm looking for a sci-fi novel I read years ago, probably between 2007-2013
I think there was a 3D-like illustration of Galileo on the front cover and the novel was part of a series.
Some teens travel back in time in a train where they have some sort of an AI assistant called ALEC (I am not too sure of the name). They went to Pisa to witness Galileo performing an experiment of how objects of different masses fall at the same rate towards the Earth.