Links
[1] http://walkiw.com/wissenswertes/physics-life
[2] http://walkiw.com/../../sites/default/files/Artikel/Ecophysics6.pdf
[3] http://walkiw.com/../../sites/default/files/Artikel/Michio-Kaku-The-Physics-of-Time-Travel.pdf
[4] http://walkiw.com/../../sites/default/files/Artikel/Michio-Kaku-The-Physics-of-Interstellar-Travel.pdf