5 Hypothetical Explanations for the Paradox 51 Extraterrestrial Life Is Rare or Non-Existent 52 No Other Intelligent Species Have Arisen 53 Intelligent Alien Species Lack Advanced Technology 54 It Is the Nature of Intelligent Life to Destroy Itself 55 It Is the Nature of Intelligent Life to Destroy Others 56 Periodic Extinction by Natural Events 57 Inflation Hypothesis and the Youngness Argument 58 Intelligent Civilizations Are Too Far Apart in Space or Time 59 It Is Too Expensive to Spread Physically Throughout the Galaxy 510 Human Beings Have Not Existed Long Enough 511 Humans Are Not Listening Properly 512 Civilizations Broadcast Detectable Radio Signals Only for a Brief Period of Time 513 They Tend to Isolate Themselves 514 They Are Too Alien 515 Everyone Is Listening No One Is Transmitting 516 Earth Is Deliberately Not Contacted 517 Earth Is Purposely Isolated Planetarium Hypothesis 518 It Is Dangerous to Communicate 519 They Are Here Undetected 520 They Are Here Unacknowledged Theweirdwideweb From the Wikipedia Page About the Fermi Paradox Given the High Scientific Probability for Alien Existence Why Can We Find No Evidence of Their Existence Whatsoever? 16They Are Too Afraid of Our Bullshit