Are time travels really possible? This book presents the physical foundations for time travel and three different types of time machines in an easily understandable way, also addressing the technical feasibility of such machines as well as the societal and political consequences of time travel. In an entertaining manner, it paints a speculative vision of the year 2100, depicting what society, politics, economics, medicine, technology, transportation, and the natural sciences might look like. To better assess this vision, it contrasts it with a look back at the year 1910. Would a person from 1910 have any idea about technological achievements such as the computer or the discovery of the expansion of the universe? Science author Andreas Müller takes the reader on adventurous journeys through time.