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