https://www.theclever.com/15-mind-blowing-things-scientists-cant-explain/
http://www.cracked.com/article_19442_8-simple-questions-you-wont-believe-science-cant-answer.html
https://www.buzzfeed.com/kellyoakes/15-things-that-scientists-just-cant-explain?utm_term=.kbAXj79n#.tpwLyJWo
http://www.cracked.com/article_20663_5-basic-things-you-wont-believe-science-cant-explain.html
https://en.wikipedia.org/wiki/Time
https://sleepfoundation.org/excessivesleepiness/content/why-do-we-need-sleep
http://hyperphysics.phy-astr.gsu.edu/hbase/Forces/funfor.html
https://www.livescience.com/1770-greatest-mysteries-gravity.html
https://www.fastcompany.com/3062239/the-bicycle-is-still-a-scientific-mystery-heres-why
https://www.livescience.com/32507-why-is-ice-slippery.html
https://www.webmd.com/brain/news/20110923/why-we-yawn#1
https://www.wired.com/2013/12/secret-language-of-plants/
https://en.wikipedia.org/wiki/Placebo