Signs in the skies in the End Times: Luke 21:25 and Joel 2:30 !
If one plots man's technical knowledge through history, one sees an exponential or "birth pang" curve on the X-Y axis, with man's knowledge right now going straight up the Y axis! This explosion of technical knowledge has only happened in the last 150 years out of a 6000 year history of man! And it correlates with the return of the nation of Israel in 1948, after an absence as free nation all the way back to 721 BC!