The free physics text available on the internet, for students and teachers, has been extended with a new section on the motion of wobbly entities (http://www.motionmountain.net/C-9-FLKN.pdf) and numerous other additions. For all fields of physics the newest research results and the main unanswered questions are presented. The present 13th revision adds the following new topics to the discussion of classical physics, relativity and quantum theory: The section on wobbly entities tells how bacteria swim and insects fly, why certain eels make knots in their bodies and what is the connection between electricity and links. (see http://www.motionmountain.net/C-9-FLKN.pdf) It is also the first chapter with a large selection of colour photographs. The section on electrodynamics explains how you can make ocean currents visible using magnetic fields and how you understand electronic circuits using the flow of water instead of the flow of electrons. It also tells how to measure the speed of light with a UNIX computer. (see http://www.motionmountain.net/C-2-CLSD.pdf) The section on extended bodies explains what is the record number of jumps for stones skipping over a water surface. In the section on quantum theory, the issues connected with entanglement have been worked out more clearly. (see http://www.motionmountain.net/C-5-QEDB.pdf) The section on global descriptions of nature discusses a simple puzzle: can a finite physics book describe all of nature, including the book itself? Can there be as much information in a book as in the whole universe containing that book? (see http://www.motionmountain.net/C-2-CLSB.pdf) The text is written for students and anybody interested in physics. But also physics teachers and physics researchers will find enough material of interest to them. The text now contains over 900 pages which provide simple, vivid and structured introductions to all fields of physics. Mechanics, special and general relativity, thermodynamics, electrodynamics, quantum theory, high energy physics and modern unification attempts are presented. Every page is written to be as surprising and challenging as possible; just open the text at random, or if you prefer, read one of the sections entitled "Curiosities": you will find the best puzzles of the field. The text explains how you can make a lamp with a cucumber and whether mind-reading is possible. The measurement limits of clocks and meter bars are explained, as well as what happens to a photographer who reduces the shutter time to the shortest value possible and what can be said about the shape of the fundamental entities in nature. The text also explains how to trigger explosions with scotch tape or with sea water. It also explains what do you need to be careful about when looking after several women or men in rapid succession and how to reverse your pullover with your hands tied. It lists the various effects matter can show. You encounter the list of open questions in physics, the issues posed by the night sky, the paradoxes of black holes, the physics of sex, strange coincidences in nature, the frequency of gravity waves, the way to connect water pipes to a turning wheel, the connection between quantum theory and the number of angels that can dance on a pin, Hilbert's sixth problem, the way David Copperfield flies, various methods for levitation, the issue of the wavefunction of the universe, the physics of pleasure and much more. In short, the text aims to give an overview of what motion is and what it can effect. As usual, I want to thank all readers who have sent corrections and suggestions. The book text can be freely downloaded at http://www.motionmountain.net Enjoy! Christoph Schiller chri_schiller @ yahoo.com I am seeking help in - providing good images to be added in the text (with permission), - drawing better figures (EPS with Adobe Illustrator), - improving the clarity of the explanations (ascii or latex), - suggesting new topics, - improving the web pages (plain html with css), - providing information on research topics (see the list given on www.motionmountain.net/support.html) so that the text can continue to be free for all readers throughout the world. I will also keep a *mailing list* with the names of anybody who wants to know about new updates of the textbook. They will appear about twice a year. Just let me know whether you want to be included.